Ion conductive solid and all-solid-state battery

Abstract

The present invention provides an ion conductive solid which contains an oxide that is represented by formula Li3+a-c-2dX2-a-b-c-dM1aM2bM3cM4dB3O9. (In the formula, X is at least one metal element selected from the group consisting of La, Pr, Nd, Sm, and Eu; M1, M2, M3, and M4 are each at least one metal element selected from the group consisting of predetermined metal elements; a, b, c, and d are predetermined real numbers; and cases where X and M2 are the same metal element are excluded.)

Description

Ionic Conductive Solid and All-Solid-State Battery

[0001] The present disclosure relates to an ionic conductive solid and an all-solid-state battery.

[0002] Conventionally, in mobile devices such as smartphones and notebook computers, and in transportation devices such as electric vehicles and hybrid electric vehicles, lightweight and high-capacity lithium-ion secondary batteries are installed. In recent years, all-solid-state batteries using an ionic conductive solid as an electrolyte, different from a liquid electrolyte, have attracted attention.

[0003] As electrolytes used in all-solid-state batteries, solid electrolytes such as oxide-based solid electrolytes and sulfide-based solid electrolytes are widely known. Among them, oxide-based solid electrolytes do not react with moisture in the air to generate hydrogen sulfide and are safer than sulfide-based solid electrolytes.

[0004] By the way, an all-solid-state battery has a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, an electrolyte containing an ionic conductive solid disposed between the positive electrode and the negative electrode, and a current collector as needed (the positive electrode active material and the negative electrode active material are also collectively referred to as "electrode active materials"). When manufacturing an all-solid-state battery using an oxide-based solid electrolyte, heat treatment is performed to reduce the contact resistance between particles of the oxide-based material contained in the solid electrolyte. However, in conventional oxide-based solid electrolytes, a high temperature of 900 °C or higher is required for heat treatment, so there is a risk that the solid electrolyte and the electrode active material react to form a high-resistance phase. The high-resistance phase may lead to a decrease in the ionic conductivity of the ionic conductive solid and, consequently, a decrease in the output of the all-solid-state battery. As oxide-based solid electrolytes that can be manufactured by heat treatment at a temperature lower than 900 °C, Li ２＋ｘ C １－ｘ B ｘ O ３ (Non-Patent Document 1) and Li ６ Y(BO ３ ) ３ (Non-Patent Document 2) can be mentioned. Li ６ Y(BO ３ ) ３ has, at 400 °C, 2.2 × 10 －３ Scm －１While the ionic conductivity is shown, it has been reported that the ionic conductivity is so low at room temperature that it cannot be measured, leading to a growing demand for materials with higher ionic conductivity.

[0005] Solid State Ionic 288 (2016) 248-252J. Mater. Chem. A, 2016, 4, 6972-6979

[0006] This disclosure provides an ion-conducting solid that can be manufactured by low-temperature heat treatment and has high ion conductivity, and an all-solid-state battery having the same.

[0007] The ion-conducting solids of this disclosure have the general formula Li ３＋ａ－ｃ－２ｄ X ２－ａ－ｂ－ｃ－ｄ M1 ａ M2 ｂ M3 ｃ M4 ｄ B ３ O ９ An ion-conducting solid containing an oxide represented by the formula, wherein the number-average particle size of the ion-conducting solid is 0.01 μm or more and 10.00 μm or less. (wherein X is at least one metallic element selected from the group consisting of La, Pr, Nd, Sm and Eu; M1 is at least one metallic element selected from the group consisting of Mg, Co, Mn, Zn, Ni, Ca, Sr and Ba; M2 is at least one metallic element selected from the group consisting of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, In, Fe, Sc, Ga and Al; M3 is at least one metallic element selected from the group consisting of Zr, Ce, Hf, Sn and Ti; M4 is at least one metallic element selected from the group consisting of V, Nb, Ta, W and Mo.) a is a real number satisfying 0.000 ≤ a ≤ 0.800, b is a real number satisfying 0.000 ≤ b ≤ 1.000, c is a real number satisfying 0.000 ≤ c ≤ 0.800, d is a real number satisfying 0.000 ≤ a + b + c + d < 2.000, except when X and M2 are the same metallic element.

[0008] Furthermore, the all-solid-state battery of the present disclosure is an all-solid-state battery having at least a positive electrode, a negative electrode, and an electrolyte, wherein at least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte contains the ion-conducting solid of the present disclosure.

[0009] According to one aspect of this disclosure, an ion-conducting solid that can be manufactured by heat treatment at low temperatures and has high ion conductivity, and an all-solid-state battery having the same can be obtained.

[0010] In this disclosure, descriptions of numerical ranges such as "XX or greater and YY or less" or "XX to YY" mean a numerical range that includes the lower and upper limits, unless otherwise specified. When numerical ranges are described in steps, the upper and lower limits of each numerical range can be any combination. In addition, in this disclosure, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ. Note that if XX is a group, multiple values ​​may be selected from XX, and the same applies to YY and ZZ. In addition, in this disclosure, "solid" refers to a substance that has a certain shape and volume among the three states of matter, and powder is included in "solid".

[0011] The ion-conducting solids of this disclosure have the general formula Li ３＋ａ－ｃ－２ｄ X ２－ａ－ｂ－ｃ－ｄ M1 ａ M2 ｂ M3 ｃ M4 ｄ B ３ O ９An ion-conducting solid containing an oxide represented by the formula, wherein the number-average particle size of the ion-conducting solid is 0.01 μm or more and 10.00 μm or less. In the formula, X is at least one metallic element selected from the group consisting of La, Pr, Nd, Sm and Eu; M1 is at least one metallic element selected from the group consisting of Mg, Co, Mn, Zn, Ni, Ca, Sr and Ba; M2 is at least one metallic element selected from the group consisting of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, In, Fe, Sc, Ga and Al; M3 is at least one metallic element selected from the group consisting of Zr, Ce, Hf, Sn and Ti; M4 is at least one metallic element selected from the group consisting of V, Nb, Ta, W and Mo. a is a real number satisfying 0.000 ≤ a ≤ 0.800, b is a real number satisfying 0.000 ≤ b ≤ 1.000, c is a real number satisfying 0.000 ≤ c ≤ 0.800, d is a real number satisfying 0.000 ≤ a + b + c + d < 2.000, except when X and M2 are the same metallic element. Except when X and M2 are the same metallic element, when X is Eu, M2 is at least one metallic element selected from the group consisting of La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, In, Fe, Sc, Ga and Al; when X is La, M2 is at least one metallic element selected from the group consisting of Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, In, Fe, Sc, Ga and Al; when X is Pr, M2 is at least one metallic element selected from the group consisting of La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, In, Fe, Sc, Ga and Al. When X is Nd, M2 is at least one metallic element selected from the group consisting of La, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, In, Fe, Sc, Ga, and Al. When X is Sm, M2 is at least one metallic element selected from the group consisting of La, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, In, Fe, Sc, Ga, and Al.

[0012] In the ionic conductive solid containing the oxide represented by the above general formula, the inventors speculate that the reason for the improved ionic conductivity is as follows. In this disclosure, the amount of at least one oxide selected from the group consisting of La, Pr, Nd, Sm, and Eu is adjusted as the raw material metal element X, thereby improving Li ３ X ２ B ３ O ９ Ionic conductivity was achieved by synthesizing and adjusting the number-average particle size. These materials have an ionic conductivity of 10 －７ ~10 －９ It was confirmed to be in the S / cm range. The substance with the obtained composition is Li ＋ The particles move more easily, and ionic conductivity is improved.

[0013] Focusing on the metallic element X of the obtained material, Non-Patent Document 2 Li ６ YB ３ O ９ In contrast to the coordination number of Y, the composition formula Li obtained in this disclosure ３ XB ３ O ９ It was confirmed that X has a coordination number of 9. By adjusting the amount of raw materials used, substances with different compositions of metal elements with different coordination numbers were obtained. Because the coordination number of metal element X is 9, Li ３ X ２ B ３ O ９ Because the composition can be obtained stably, Li ＋ This makes it easier for the elements to move, improving ionic conductivity. Furthermore, some of the metal elements X may be substituted with other metal elements such as M1 to M4, and it is also preferable to use a combination of elemental substitutions between elements with different valencies.

[0014] X preferably has an ionic radius of 1.090 to 1.250 Å when its coordination number is 9, more preferably 1.100 to 1.240 Å, and particularly preferably 1.110 to 1.230 Å. By being within the above range, Li ３ X ２ B ３ O ９It is possible to obtain a stable composition. As a result, Li ＋ Because the molecules move more easily, the ionic conductivity improves. Also, if the ionic radius is less than 1.090 Å, the target Li ３ X ２ B ３ O ９ The composition cannot be obtained.

[0015] Ion-conducting solids preferably have a monoclinic crystal structure.

[0016] The number-average particle size of the ion-conducting solid is 0.01 μm or more and 10.00 μm or less. Preferably, the number-average particle size is 0.01 μm or more and 5.00 μm or less, and more preferably 0.01 μm or more and 3.00 μm or less. Within this range, the grain boundary resistance within the ion-conducting solid is reduced, and the ion conductivity is further improved. If the particle size exceeds 10.00 μm, the ion-conducting solid will not become dense, and Li ＋ Ion conduction is inhibited. The number-average particle size of ion-conducting solids can be controlled by grinding, classification, and wet grinding using organic solvents.

[0017] In the above general formula, a is a real number satisfying 0.000 ≤ a ≤ 0.800. Preferably, a is 0.000 ≤ a ≤ 0.400, and more preferably 0.000 ≤ a ≤ 0.300.

[0018] In the above general formula, b is a real number satisfying 0.000 ≤ b ≤ 1.000. Preferably, b is 0.000 ≤ b ≤ 0.800, and more preferably 0.000 ≤ b ≤ 0.600.

[0019] In the above general formula, c is a real number satisfying 0.000 ≤ c ≤ 0.800. Preferably, c is 0.000 ≤ c ≤ 0.400, more preferably 0.000 ≤ c ≤ 0.200. Also, c may preferably be 0.050 ≤ c ≤ 0.400, more preferably 0.080 ≤ c ≤ 0.200.

[0020] In the above general formula, d is a real number satisfying 0.000 ≤ d ≤ 0.800. Preferably, d is 0.000 ≤ d ≤ 0.400.

[0021] In the above formula, a + b + c + d is a real number satisfying 0.000 ≤ a + b + c + d < 2.000. Preferably, a + b + c + d is 0.000 ≤ a + b + c + d < 1.800, more preferably 0.000 ≤ a + b + c + d < 1.600, even more preferably 0.010 ≤ a + b + c + d < 0.500, particularly preferably 0.050 ≤ a + b + c + d < 0.300, and most preferably 0.080 ≤ a + b + c + d < 0.250.

[0022] X ２－ａ－ｂ－ｃ－ｄ In this equation, 2-a-b-c-d is preferably 1.000 ≤ 2-a-b-c-d, more preferably 1.200 ≤ 2-a-b-c-d, and even more preferably 1.400 ≤ 2-a-b-c-d. There is no particular upper limit.

[0023] The ion-conducting solid can be, for example, the following embodiments, but is not limited to these embodiments. (1) It is preferable that a satisfies a = 0.000, b satisfies b = 0.000, c satisfies c = 0.000, and d satisfies d = 0.000. (2) It is preferable that a satisfies 0.000 ≤ a ≤ 0.100, b satisfies 0.000 ≤ b ≤ 1.000, c satisfies 0.000 ≤ c ≤ 0.200, d satisfies 0.000 ≤ d ≤ 0.100, and a, b, c, d satisfy 0.000 ≤ a + b + c + d < 1.000. (3) It is desirable that a satisfies 0.010 ≤ a ≤ 0.100, b satisfies 0.000 ≤ b ≤ 0.500, c satisfies 0.000 ≤ c ≤ 0.200, d satisfies 0.010 ≤ d ≤ 0.100, and a, b, c, d satisfy 0.010 ≤ a + b + c + d < 0.700. M1, M2, M3, and M4 in the above general formula may or may not be included in the formula.

[0024] In the above general formula, M1 is at least one metallic element selected from the group consisting of Mg, Co, Mn, Zn, Ni, Ca, Sr, and Ba. Preferably, M1 is at least one metallic element selected from the group consisting of Mg, Co, Mn, Zn, Ni, Ca, Sr, and Ba, and more preferably, at least one metallic element selected from the group consisting of Mg, Co, and Zn.

[0025] In the above general formula, M2 is at least one metallic element selected from the group consisting of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, In, Fe, Sc, Ga, and Al. Preferably, M2 is at least one metallic element selected from the group consisting of La, Pr, Nd, Sm, Eu, and Gd, and more preferably, at least one metallic element selected from the group consisting of La, Pr, Nd, Sm, and Eu.

[0026] In the above general formula, M3 is at least one metallic element selected from the group consisting of Zr, Ce, Hf, Sn, and Ti. Preferably, M3 is at least one metallic element selected from the group consisting of Zr, Ce, Hf, and Sn, and more preferably, at least one metallic element selected from the group consisting of Zr, Ce, and Hf.

[0027] In the above general formula, M4 is at least one metallic element selected from the group consisting of V, Nb, Ta, W, and Mo. Preferably, M4 is at least one metallic element selected from the group consisting of Nb, Ta, W, and Mo.

[0028] Furthermore, if a portion of the trivalent metallic element X is replaced with specific elements M1, M2, M3, and M4 in a specific ratio range, the charge balance is adjusted by the substitution of elements with different valencies. Therefore, Li in the crystal lattice ＋ This results in a state of excess or deficiency. ＋ To compensate for the excess or deficiency of the surrounding Li ＋ As these particles move, ionic conductivity becomes more readily apparent.

[0029] Next, a method for manufacturing an ion-conducting solid will be described. The method for manufacturing an ion-conducting solid can be as follows, but is not limited thereto. General formula Li ３＋ａ－ｃ－２ｄ X ２－ａ－ｂ－ｃ－ｄ M1 ａ M2 ｂ M3 ｃ M4 ｄ B ３ O ９A method for producing an ion-conducting solid containing an oxide represented by the general formula, which may include a primary calcination step of heating raw materials mixed to obtain the oxide represented by the general formula at a temperature below the melting point of the oxide. In the formula, X is at least one metallic element selected from the group consisting of La, Pr, Nd, Sm, and Eu; M1 is at least one metallic element selected from the group consisting of Mg, Co, Mn, Zn, Ni, Ca, Sr, and Ba; M2 is at least one metallic element selected from the group consisting of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, In, Fe, Sc, Ga, and Al; M3 is at least one metallic element selected from the group consisting of Zr, Ce, Hf, Sn, and Ti; M4 is at least one metallic element selected from the group consisting of V, Nb, Ta, W, and Mo. a is a real number satisfying 0.000 ≤ a ≤ 0.800, b is a real number satisfying 0.000 ≤ b ≤ 1.000, c is a real number satisfying 0.000 ≤ c ≤ 0.800, d is a real number satisfying 0.000 ≤ a + b + c + d < 2.000, except when X and M2 are the same metallic element.

[0030] The method for producing an ion-conducting solid according to this disclosure may include a primary firing step in which raw materials are weighed and mixed to obtain an oxide represented by the above general formula, and the raw materials are heat-treated at a temperature below the melting point of the oxide to produce an ion-conducting solid containing the oxide. The ion-conducting solid can be obtained by the primary firing step. Furthermore, the production method may optionally include a secondary firing step in which the obtained ion-conducting solid containing the oxide is heat-treated at a temperature below the melting point of the oxide to produce a sintered body of the ion-conducting solid containing the oxide. The method for producing an ion-conducting solid according to this disclosure, including the above primary firing step and the above secondary firing step, will be described in detail below, but this disclosure is not limited to the production method described below.

[0031] Primary firing process In the primary firing process, the general formula Li ３＋ａ－ｃ－２ｄ X ２－ａ－ｂ－ｃ－ｄ M1 ａ M2 ｂ M3 ｃ M4 ｄ B３ O ９ (However, X is at least one metallic element selected from the group consisting of La, Pr, Nd, Sm and Eu; M1 is at least one metallic element selected from the group consisting of Mg, Co, Mn, Zn, Ni, Ca, Sr and Ba; M2 is at least one metallic element selected from the group consisting of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, In, Fe, Sc, Ga and Al; M3 is at least one metallic element selected from the group consisting of Zr, Ce, Hf, Sn and Ti; M4 is at least one metallic element selected from the group consisting of V, Nb, Ta, W and Mo) a is a real number satisfying 0.000 ≤ a ≤ 0.800, b is a real number satisfying 0.000 ≤ b ≤ 1.000, c is a real number satisfying 0.000 ≤ c ≤ 0.800, d is a real number satisfying 0.000 ≤ a + b + c + d < 2.000, except when X and M2 are the same metallic element.) Chemical reagent grade Li ２ CO ３ , H ３ BO ３ , Eu ２ O ３ ZnO, ZrO ２ , CEO ２ The raw materials, such as [list of raw materials], are weighed in stoichiometric quantities and mixed.

[0032] The device used for mixing is not particularly limited. For example, a pulverizing mixer such as a planetary ball mill can be used. The material and capacity of the container used for mixing, as well as the material and diameter of the balls, are not particularly limited and can be appropriately selected according to the type and amount of raw materials used. As an example, a 45 mL container made of zirconia and balls with a diameter of 5 mm made of zirconia can be used. Also, the conditions for the mixing process are not particularly limited. For example, the rotation speed can be 50 rpm to 2000 rpm, and the time can be 10 minutes to 60 minutes. After obtaining the mixed powder of the above raw materials by the mixing process, the obtained mixed powder is pressure-molded into pellets. As the pressure molding method, known pressure molding methods such as cold uniaxial molding method and cold isostatic pressure molding method can be used. The conditions for pressure molding in the primary firing process are not particularly limited. For example, the pressure can be 100 MPa to 200 MPa. For the obtained pellets, firing is performed using a firing device such as an atmospheric firing device. The temperature for primary firing to perform solid-phase synthesis is not particularly limited as long as it is below the melting point of the ion-conductive solid represented by the general formula Li ３＋ａ－ｃ－２ｄ X ２－ａ－ｂ－ｃ－ｄ M1 ａ M2 ｂ M3 ｃ M4 ｄ B ３ O ９ For example, it can be less than 775 °C, 750 °C or lower, 725 °C or lower, 700 °C or lower, or 675 °C or lower, and can be, for example, 500 °C or higher. These numerical ranges can be arbitrarily combined. At temperatures within the above ranges, solid-phase synthesis can be sufficiently performed. The time for the primary firing process is not particularly limited, but can be, for example, about 500 minutes to 3000 minutes. By the above primary firing process, the above general formula Li ３＋ａ－ｃ－２ｄ X ２－ａ－ｂ－ｃ－ｄ M1 ａ M2 ｂ M3 ｃ M4 ｄ B ３ O ９An ion-conducting solid containing the oxide represented by [formula] can be prepared. A powder of the ion-conducting solid containing the oxide can also be obtained by grinding the ion-conducting solid using a mortar and pestle, a planetary mill, or wet grinding in an organic solvent.

[0033] In the secondary firing process, at least one selected from the group consisting of an ion-conducting solid containing an oxide obtained in the primary firing process and a powder of an ion-conducting solid containing an oxide is pressure-molded as needed and fired to obtain a sintered body of an ion-conducting solid containing an oxide. Pressure molding and secondary firing may be performed simultaneously using discharge plasma sintering (hereinafter also simply referred to as "SPS") or hot pressing, or pellets may be produced by cold uniaxial molding and then secondary firing may be performed in an atmospheric atmosphere, an oxidizing atmosphere or a reducing atmosphere. Under the above conditions, an ion-conducting solid with high ion conductivity can be obtained without melting due to heat treatment. The conditions for pressure molding in the secondary firing process are not particularly limited, but for example, the pressure can be 10 MPa to 100 MPa. The temperature for secondary firing is given by the general formula Li ３＋ａ－ｃ－２ｄ X ２－ａ－ｂ－ｃ－ｄ M1 ａ M2 ｂ M3 ｃ M4 ｄ B ３ O ９ The melting point of the ion-conducting solid represented by [formula] is below [value]. The temperature during secondary firing is preferably less than 775°C, more preferably 750°C or lower, even more preferably 725°C or lower, and particularly preferably 700°C or lower. The lower limit of the temperature is not particularly limited, and the lower the better, but for example, it is 500°C or higher. The numerical range can be arbitrarily combined, but for example, it can be in the range of 500°C or higher and less than 775°C. Within the above range, it is possible to suppress the melting or decomposition of the ion-conducting solid containing the oxide of this disclosure during the secondary firing process, and a sufficiently sintered sintered body of the ion-conducting solid containing the oxide of this disclosure can be obtained. The time of the secondary firing process can be appropriately changed depending on the temperature and pressure of the secondary firing, but it is preferably 24 hours or less, and may be 14 hours or less. The time of the secondary firing process may be, for example, 5 minutes or more, 1 hour or more, or 6 hours or more.

[0034] The method for cooling the sintered body of the ion-conducting solid containing the oxide of the present disclosure obtained by the secondary firing process is not particularly limited. It may be cooled naturally (cooled in a furnace), rapidly, more gradually than natural cooling, or maintained at a certain temperature during cooling.

[0035] Next, the all-solid-state battery of the present disclosure will be described. An all-solid-state battery generally comprises a positive electrode, a negative electrode, an electrolyte containing an ion-conducting solid disposed between the positive and negative electrodes, and optionally a current collector.

[0036] The all-solid-state battery of the present disclosure is an all-solid-state battery having at least a positive electrode, a negative electrode, and an electrolyte, wherein at least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte comprises an ion-conducting solid of the present disclosure.

[0037] The all-solid-state battery disclosed herein may be a bulk-type battery or a thin-film battery. The specific shape of the all-solid-state battery disclosed herein is not particularly limited, but examples include coin-type, button-type, sheet-type, and stacked-type batteries.

[0038] The all-solid-state battery of this disclosure has an electrolyte. Furthermore, in the all-solid-state battery of this disclosure, it is preferable that at least the electrolyte includes the ion-conducting solid of this disclosure. The solid electrolyte in the all-solid-state battery of this disclosure may be the ion-conducting solid of this disclosure, may contain other ion-conducting solids, or may contain an ionic liquid or a gel polymer. Other ion-conducting solids are not particularly limited and may include ion-conducting solids commonly used in all-solid-state batteries, such as LiI, Li... ３ PO ４ Li ７ La ３ Zr ２ O １２ The following may be included. The content of the ion-conducting solid of the present disclosure in the electrolyte of the all-solid-state battery of the present disclosure is not particularly limited, but is preferably 25% by mass or more, more preferably 50% by mass or more, even more preferably 75% by mass or more, and particularly preferably 100% by mass.

[0039] The all-solid-state battery of the present disclosure has a positive electrode. The positive electrode may contain a positive electrode active material, or it may contain the positive electrode active material and the ion-conducting solid of the present disclosure. As the positive electrode active material, known positive electrode active materials such as sulfides containing transition metal elements or oxides containing lithium and transition metal elements can be used without particular limitation. For example, LiNiVO ４ LiCoPO ４ LiCoVO ４ LiMn １．６ Ni ０．４ O ４ LiMn ２ O ４ LiCoO ２ Fe ２ (SO ４ ) ３ LiFePO ４ LiNi １／３ Mn １／３ Co １／３ O ２ LiNi １／２ Mn １／２ O ２ LiNiO ２ Li １＋ｘ (Fe, Mn, Co) １－ｘ O ２ LiNi ０．８ Co ０．１５ Al ０．０５ O ２ These are some examples. Furthermore, the positive electrode may contain a binder, a conductive agent, etc. Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, and polyvinyl alcohol. Examples of conductive agents include natural graphite, artificial graphite, acetylene black, ethylene black, and gas-phase carbon fiber.

[0040] The all-solid-state battery of the present disclosure has a negative electrode. The negative electrode may contain a negative electrode active material, or it may contain the negative electrode active material and the ion-conducting solid of the present disclosure. As the negative electrode active material, known negative electrode active materials such as lithium, lithium alloys, tin compounds and other inorganic compounds, carbonaceous materials capable of absorbing and releasing lithium ions, and conductive polymers can be used without particular limitation. For example, Li ４ Ti ５ O １２These are some examples. Furthermore, the negative electrode may contain a binder, a conductive agent, etc. The same binder and conductive agent as those listed for the positive electrode can be used.

[0041] Here, "containing" an electrode means that the electrode has the electrode active material as a component, element, or property. For example, both cases where the electrode contains the electrode active material within the electrode and cases where the electrode active material is coated on the electrode surface fall under the above definition of "containing".

[0042] The positive and negative electrodes can be obtained by known methods such as mixing, molding, and heat-treating raw materials. This allows the ion-conducting solid to penetrate into gaps between electrode active materials, making it easier to secure lithium ion conduction pathways. The ion-conducting solid of this disclosure can be manufactured by heat treatment at a lower temperature compared to conventional techniques, which is thought to suppress the formation of a high-resistance phase that occurs when the ion-conducting solid reacts with the electrode active material.

[0043] The positive electrode and the negative electrode may have a current collector. Known current collectors such as aluminum, titanium, stainless steel, nickel, iron, calcined carbon, conductive polymer, and conductive glass can be used as current collectors. In addition, for the purpose of improving adhesion, conductivity, oxidation resistance, etc., aluminum, copper, etc., can be used as current collectors, which have their surfaces treated with carbon, nickel, titanium, silver, etc.

[0044] The all-solid-state battery disclosed herein can be obtained by known methods, such as stacking a positive electrode, a solid electrolyte, and a negative electrode, then molding and heat-treating them. Since the ion-conducting solid of this disclosure can be manufactured by heat treatment at a lower temperature compared to the prior art, it is thought that the formation of a high-resistance phase resulting from the reaction between the ion-conducting solid and the electrode active material can be suppressed, and thus an all-solid-state battery with excellent output characteristics can be obtained.

[0045] Next, the methods for measuring the composition and each physical property related to this disclosure will be described. • Method for identifying and analyzing contained metals The compositional analysis of ion-conducting solids is performed using wavelength-dispersive X-ray fluorescence analysis (hereinafter also referred to as XRF) with a sample solidified by a pressure molding method. However, if analysis is difficult due to particle size effects, etc., it is preferable to vitrify the ion-conducting solid using the glass bead method and perform compositional analysis by XRF. Alternatively, compositional analysis may be performed by inductively coupled high-frequency plasma emission spectroscopy (ICP-AES). In the case of XRF, the analyzer used is the Rigaku ZSX Primus II. The analysis conditions are as follows: Rh is used as the anode of the X-ray tube, in a vacuum atmosphere, with an analysis diameter of 10 mm, an analysis range of 17 deg to 81 deg, a step size of 0.01 deg, and a scan speed of 5 sec / step. Furthermore, light elements are detected using a proportional counter, and heavy elements are detected using a scintillation counter. Based on the peak positions of the spectra obtained by XRF, the elements are identified, and the molar concentration ratios are calculated from the count rate (unit: cps), which is the number of X-ray photons per unit time, to determine a, b, c, and d.

[0046] The following describes specific examples of the fabrication and evaluation of the ion-conducting solids of this disclosure. However, this disclosure is not limited to the following examples. The raw materials used in this disclosure are as follows. Specifically, in each example and comparative example, raw materials having the metal elements listed in the M1 to M4 columns of Tables 1-1 to 1-4, 2-1 to 2-4, 3-1 to 3-4, 4-1 to 4-4, and 5-1 to 5-4 were used. For example, in Example 2, MgO was used as the M1 source. In Example 18, MgO and ZnO were used as the M1 source in a molar ratio of 1:1.

[0047] Li ２ CO ３ (Manufactured by Nacalai Tesque, purity 99.0% by mass), H ３ BO ３ (manufactured by Kanto Chemical, purity 99.5%), X source and M2 source: Eu ２ O ３ (Manufactured by Shin-Etsu Chemical Co., Ltd., 99.9% purity), Sm ２ O ３(Manufactured by Fujifilm Wako Pure Chemical Industries, 99.9% purity), Nd ２ O ３ (manufactured by Kojundo Kagaku Kenkyusho, purity 99.9% by mass), Pr ６ O １１ (Manufactured by Shin-Etsu Chemical Co., Ltd., 99.9% purity), La ２ O ３ (Fujifilm Wako Pure Chemical Industries, Ltd., purity 99.9% by mass), M1 source: MgO (manufactured by Ube Materials, purity 99.0% by mass), CoO (manufactured by Kojundo Chemical Research Institute, purity 99.7%), NiO (manufactured by Wako Pure Chemical Industries, purity 99.9% by mass), MnO (manufactured by Kanto Chemical, purity 80 0% by mass), ZnO (manufactured by Wako Pure Chemical Industries, purity 99% by mass), CaO (manufactured by Kanto Chemical, purity 97.0%), SrO (manufactured by Kojundo Chemical Research Institute, purity 98%), BaO (manufactured by Wako Pure Chemical Industries, purity 90.0% by mass). M2 source: Gd ２ O ３ (Manufactured by Shin-Etsu Chemical Co., Ltd., purity 99.9% by mass), Tb ２ O ３ (Manufactured by Shin-Etsu Chemical Co., Ltd., purity 99.9% by mass), Dy ２ O ３ (Manufactured by Shin-Etsu Chemical Co., Ltd., purity 95% by mass), Ho ２ O ３ (manufactured by Kojundo Kagaku Kenkyusho, purity 99.9% by mass), Y ２ O ３ (Manufactured by Shin-Etsu Chemical Co., Ltd., purity 99.9% by mass), Er ２ O ３ (Manufactured by Shin-Etsu Chemical Co., Ltd., purity 95% by mass), Tm ２ O ３ (manufactured by Kojundo Kagaku Kenkyusho, purity 99.9% by mass), Yb ２ O ３ (Manufactured by Shin-Etsu Chemical Co., Ltd., purity 99.9% by mass), Lu ２ O ３ (manufactured by Kojundo Kagaku Kenkyusho, purity 99.9% by mass), In ２ O ３ (manufactured by Shinko Kagaku Kogyo, purity 99% by mass), Fe ２ O ３ (manufactured by Wako Pure Chemical Industries, purity 95.0% by mass), Sc ２ O ３ (manufactured by Kojundo Kagaku Kenkyusho, purity 99.9% by mass), GaO (manufactured by Rare Metals, 99.99%), Al ２ O ３(Showa Denko 99.0% purity) M3 source: ZrO ２ (Manufactured by Shin-Nippon Denko, 99.9% purity), CeO ２ (Manufactured by Shin-Etsu Chemical Co., Ltd., 99.9% purity, HfO) ２ (New Metals, 99.9% purity), SnO ２ (Manufactured by Mitsuwa Chemical Co., Ltd., 99.9% purity), TiO ２ (Made by Toho Titanium, 99% purity) M4 source: V ２ O ５ (Manufactured by Fujifilm Wako Pure Chemical Industries, 99.0% purity, Nb) ２ O ５ (Manufactured by Mitsui Mining & Smelting Co., Ltd., 99.9% purity), Ta ２ O ５ (Manufactured by Kanto Chemical, 99% by mass purity), WO ３ (Made in Japan by tungsten, 99% purity by mass), MoO ３ (Manufactured by Fujifilm Wako Pure Chemical Industries, purity 99.0%) Comparative example: Li ３ BO ３ (Manufactured by Toyoshima Seisakusho, 99% purity by mass)

[0048] [Example 1] ・Primary firing process Li ２ CO ３ , H ３ BO ３ , and Eu ２ O ３Using the above as raw materials, each raw material was weighed in stoichiometric amounts so that a to d were the values ​​listed in Table 1-1, and mixed in a Fritsch P-7 planetary mill at a disk rotation speed of 300 rpm for 30 minutes. A 5 mm diameter zirconia ball and a 45 mL container were used in the planetary mill. After mixing, the mixed powder was cold-formed uniaxially at 147 MPa using an NPA Systems 100 kN electric press P3052-10, and then fired in an atmospheric environment. The heating temperature was 700°C and the holding time was 720 minutes. The obtained ion-conducting solid containing oxide was pulverized in a Fritsch P-7 planetary mill at a disk rotation speed of 400 rpm for 180 minutes to produce a powder of the ion-conducting solid containing oxide. Secondary firing process The powder of the ion-conducting solid containing oxide obtained above was molded and secondary fired to produce a sintered body of the ion-conducting solid containing oxide of Example 1. The powder was cold-formed uniaxially at 147 MPa using an NPA Systems 100 kN electric press P3052-10. Secondary firing was carried out in an air atmosphere at a heating temperature of 700°C for a holding time of 60 minutes.

[0049] [Examples 2-83] Using materials having the metal elements listed in columns M1-M4 in Tables 1-1-1-4, each raw material was weighed in stoichiometric amounts so that a-d were the values ​​listed in Tables 1-1-1-4, and the heating temperatures for the primary and secondary firing processes were carried out at the temperatures listed in Tables 1-1-1-4, the same process as in Example 1 was used to produce sintered bodies of ion-conducting solids containing the oxides of Examples 2-83.

[0050] [Comparative Example 1] Li ３ BO ３ Using the same process as in Example 1, a sintered ion-conducting solid body containing the oxide of Comparative Example 1 was prepared.

[0051] [Comparative Example 2] A sintered ion-conducting solid body containing the oxide of Comparative Example 2 was produced using the same process as in Example 1, except that the disk rotation speed during grinding after the initial firing process in Example 1 was set to 150 rpm and the grinding time was set to 30 minutes.

[0052] [Comparative Example 3] A sintered ion-conducting solid body containing the oxide of Comparative Example 3 was produced using the same process as in Example 11, except that the disk rotation speed during grinding after the initial firing process in Example 11 was set to 150 rpm and the grinding time was set to 30 minutes.

[0053] [Comparative Example 4] A sintered solid ion-conducting body containing the oxide of Comparative Example 4 was produced using the same process as in Example 66, except that the disk rotation speed during grinding after the initial firing process in Example 66 was set to 150 rpm and the grinding time was set to 30 minutes.

[0054] [Examples 101-183] EU ２ O ３ Sm ２ O ３ Using the same process as in Example 1, sintered bodies of ion-conducting solids containing the oxides of Examples 101 to 183 were produced using raw materials having the metal elements listed in columns M1 to M4 in Tables 2-1 to 2-4, weighing each raw material in stoichiometric amounts so that a to d were the values ​​listed in Tables 2-1 to 2-4, and carrying out the heating temperature of the primary and secondary firing processes at the temperatures listed in Tables 2-1 to 2-4.

[0055] [Comparative Example 12] A sintered ion-conducting solid body containing the oxide of Comparative Example 12 was produced using the same process as in Example 101, except that the disk rotation speed during grinding after the initial firing process in Example 101 was set to 150 rpm and the grinding time was set to 30 minutes.

[0056] [Comparative Example 13] A sintered ion-conducting solid body containing the oxide of Comparative Example 13 was produced using the same process as in Example 111, except that the disk rotation speed during grinding after the initial firing process in Example 111 was set to 150 rpm and the grinding time was set to 30 minutes.

[0057] [Comparative Example 14] A sintered solid ion-conducting body containing the oxide of Comparative Example 14 was produced using the same process as in Example 166, except that the disk rotation speed during grinding after the initial firing process in Example 166 was set to 150 rpm and the grinding time was set to 30 minutes.

[0058] [Examples 201-282] EU ２O ３ Nd ２ O ３ Using the same process as in Example 1, sintered bodies of ion-conducting solids containing the oxides of Examples 201 to 282 were prepared using raw materials having the metal elements listed in columns M1 to M4 in Tables 3-1 to 3-4, weighing each raw material in stoichiometric amounts so that a to d were the values ​​listed in Tables 3-1 to 3-4, and carrying out the heating temperature of the primary and secondary firing processes at the temperatures listed in Tables 3-1 to 3-4.

[0059] [Comparative Example 22] A sintered body of an ion-conducting solid containing the oxide of Comparative Example 22 was produced using the same process as in Example 201, except that the disk rotation speed during grinding after the initial firing process in Example 201 was set to 150 rpm and the grinding time was set to 30 minutes.

[0060] [Comparative Example 23] A sintered solid ion-conducting body containing the oxide of Comparative Example 23 was produced using the same process as in Example 211, except that the disk rotation speed during grinding after the initial firing process in Example 211 was set to 150 rpm and the grinding time was set to 30 minutes.

[0061] [Comparative Example 24] A sintered solid ion-conducting body containing the oxide of Comparative Example 24 was produced using the same process as in Example 266, except that the disk rotation speed during grinding after the initial firing process in Example 266 was set to 150 rpm and the grinding time was set to 30 minutes.

[0062] [Examples 301-383] EU ２ O ３ Instead of Pr ６ O １１ Using the same process as in Example 1, sintered bodies of ion-conducting solids containing the oxides of Examples 301 to 383 were prepared using raw materials having the metal elements listed in columns M1 to M4 in Tables 4-1 to 4-4, weighing each raw material in stoichiometric amounts so that a to d were the values ​​listed in Tables 4-1 to 4-4, and carrying out the heating temperature of the primary and secondary firing processes at the temperatures listed in Tables 4-1 to 4-4.

[0063] [Comparative Example 32] A sintered solid ion-conducting body containing the oxide of Comparative Example 32 was produced using the same process as in Example 301, except that the disk rotation speed during grinding after the initial firing process in Example 301 was set to 150 rpm and the grinding time was set to 30 minutes.

[0064] [Comparative Example 33] A sintered ion-conducting solid body containing the oxide of Comparative Example 33 was produced using the same process as in Example 311, except that the disk rotation speed during grinding after the initial firing process in Example 311 was set to 150 rpm and the grinding time was set to 30 minutes.

[0065] [Comparative Example 34] A sintered solid ion-conducting body containing the oxide of Comparative Example 34 was produced using the same process as in Example 366, except that the disk rotation speed during grinding after the initial firing process in Example 366 was set to 150 rpm and the grinding time was set to 30 minutes.

[0066] [Examples 401-483] EU ２ O ３ La instead ２ O ３ Using the same process as in Example 1, sintered bodies of ion-conducting solids containing the oxides of Examples 401 to 483 were produced using raw materials having the metal elements listed in columns M1 to M4 in Tables 5-1 to 5-4, weighing each raw material in stoichiometric amounts so that a to d were the values ​​listed in Tables 5-1 to 5-4, and carrying out the heating temperature of the primary and secondary firing processes at the temperatures listed in Tables 5-1 to 5-4.

[0067] [Comparative Example 42] A sintered body of an ion-conducting solid containing the oxide of Comparative Example 42 was produced using the same process as in Example 401, except that the disk rotation speed during grinding after the initial firing process in Example 401 was set to 150 rpm and the grinding time was set to 30 minutes.

[0068] [Comparative Example 43] A sintered ion-conducting solid body containing the oxide of Comparative Example 43 was produced using the same process as in Example 411, except that the disk rotation speed during grinding after the initial firing process in Example 411 was set to 150 rpm and the grinding time was set to 30 minutes.

[0069] [Comparative Example 44] A sintered solid ion-conducting body containing the oxide of Comparative Example 44 was produced using the same process as in Example 466, except that the disk rotation speed during grinding after the initial firing process in Example 466 was set to 150 rpm and the grinding time was set to 30 minutes.

[0070] The sintered bodies of ion-conducting solids containing oxides in Examples 1-83, 101-183, 201-282, 301-383, 401-483, and Comparative Examples 1-4, 12-14, 22-24, 32-34, and 42-44 were subjected to compositional analysis using the method described above. In addition, the number-average particle size of the ion-conducting solid powders obtained in Examples 1-83, 101-183, 201-282, 301-383, 401-483, and Comparative Examples 1-4, 12-14, 22-24, 32-34, and 42-44, and the ion conductivity of the sintered bodies of the ion-conducting solids were measured using the following methods. The methods for measuring ion conductivity and number-average particle size are described below. Furthermore, the obtained evaluation results are shown in Tables 1-1 to 1-4, 2-1 to 2-4, 3-1 to 3-4, 4-1 to 4-4, and 5-1 to 5-4.

[0071] - Measurement of Ion Conductivity In a sintered body of an ion-conductive solid containing an oxide in a flat plate shape obtained by secondary firing, two parallel, large-area surfaces were polished with sandpaper. The dimensions of the sintered body of the ion-conductive solid containing an oxide can be, for example, 0.9 cm × 0.9 cm × 0.05 cm, but are not limited to this. Polishing was performed by first using #500 for 15 to 30 minutes, then using #1000 for 10 to 20 minutes, and finally using #2000 for 5 to 10 minutes. Polishing was considered complete when there were no noticeable irregularities or scratches on the polished surface by visual inspection. After polishing, gold was deposited on the polished surface of the sintered body of the ion-conductive solid containing an oxide using a Sanyu Electronics sputtering system SC-701MkII ADVANCE. The deposition conditions were Ar as the process gas, a vacuum of 2 Pa to 5 Pa, and a deposition time of 5 minutes for the measurement sample. After deposition, the AC impedance of the measurement sample was measured. For impedance measurements, an impedance / gain phase analyzer SI1260 and a dielectric interface system 1296 (both manufactured by Solartron) were used. The measurement conditions were a temperature of 27°C, an amplitude of 20 mV, and a frequency of 0.1 Hz to 1 MHz. The resistance of the sintered ion-conducting solid containing oxide was calculated using the Nyquist plot obtained from the impedance measurement and the AC analysis software ZVIEW from Scribner. An equivalent circuit corresponding to the measurement sample was set in ZVIEW, and the resistance of the sintered ion-conducting solid containing oxide was calculated by fitting and analyzing the equivalent circuit and the Nyquist plot. Using the calculated resistance, the thickness of the sintered ion-conducting solid containing oxide, and the electrode area, the ionic conductivity was calculated from the following formula: Ionic conductivity (S / cm) = Thickness of the sintered ion-conducting solid containing oxide (cm) / (Resistance of the sintered ion-conducting solid containing oxide (Ω) × Electrode area (cm) ２ ))

[0072] The ionic conductivity (S / cm) of a sintered solid that conducts ionically is, for example, 1.00 × 10⁻⁶. －９ It may be S / cm or more, preferably 8.00 × 10 －９ The ratio is S / cm or higher, and more preferably 1.00 × 10 －８ The ratio is S / cm or higher, and more preferably 1.00 × 10 －７The conductivity should be S / cm or higher. Higher conductivity is preferable, and there is no particular upper limit, but for example, 1.00 × 10 －２ S / cm or less, 1.00×10 －３ S / cm or less, 1.00×10 －４ It is less than or equal to S / cm. For example, preferably 1.00 × 10 －９ S / cm or more 1.00×10 －２ S / cm or less, 8.00×10 －９ S / cm or more 1.00×10 －３ S / cm or less, 1.00×10 －８ S / cm or more 1.00×10 －４ S / cm or less, 1.00×10 －７ S / cm or more 1.00×10 －４ Examples include S / cm or less.

[0073] - Evaluation of number-average particle size: The particle size distribution of an ion-conductive solid powder containing oxides, obtained by ball milling (Fritsch planetary mill P-7) after primary calcination, was measured using a Horiba LA-960V2 laser diffraction / scattering particle size distribution analyzer. The refractive index was set to 1.8, and ethanol was used as the measurement solvent. The sample concentration was adjusted so that the transmittance was between 90% and 70%. The number-average particle size was calculated from the obtained frequency distribution.

[0074] - Results Tables 1-1 to 1-4, 2-1 to 2-4, 3-1 to 3-4, 4-1 to 4-4, and 5-1 to 5-4 show the stoichiometric amounts of raw materials (general formula Li) used when producing sintered bodies of ion-conducting solids containing the oxides of Examples 1 to 83, 101 to 183, 201 to 282, 301 to 383, 401 to 483, and Comparative Examples 1 to 4, 12 to 14, 22 to 24, 32 to 34, and 42 to 44. ６＋ａ－ｃ－２ｄ X １－ａ－ｂ－ｃ－ｄ M1 ａ M2 ｂ M3 ｃ M4 ｄ B ３ O ９The values ​​of a, b, c, and d, number-average particle size, and ionic conductivity were summarized. The above compositional analysis confirmed that the sintered ionic conductive solids containing oxides in each example and comparative example all had the composition as indicated by the stoichiometric amounts of the raw materials listed in each table. Furthermore, the sintered ionic conductive solids containing oxides in each example exhibited high ionic conductivity even when fired at temperatures below 775°C.

[0075] In each table, the ionic conductivity of the ionic conductive solids prepared in Examples 1, 101, 201, 301, and 401 was improved compared to Comparative Example 1. By adjusting the amount of at least one oxide selected from the group consisting of La, Pr, Nd, Sm, and Eu as the raw material metal element X, Li ３ X ２ B ３ O ９ It has been shown that higher ionic conductivity can be obtained by synthesizing and adjusting the particle size of Li. ３ B ３ O ９ In contrast, the ion-conducting solids of this disclosure exhibit higher ion conductivity.

[0076] Tables 1-1 to 1-4 show that the ionic conductivity of the ionic conductive solids prepared in Examples 1, 11, and 66 was improved compared to Comparative Examples 2 to 4, indicating that higher ionic conductivity can be obtained by reducing the number-average particle size to 10 μm or less. This demonstrates that by reducing the particle size, a denser ionic conductive solid can be prepared, resulting in higher ionic conductivity.

[0077] Tables 2-1 to 2-4, 3-1 to 3-4, 4-1 to 4-4, and 5-1 to 5-4 show that, similar to Tables 1-1 to 1-4, higher ionic conductivity can be obtained by reducing the number-average particle size to 10 μm or less. This indicates that by reducing the particle size, a denser ionic conductive solid can be fabricated, resulting in higher ionic conductivity.

Claims

1. General formula Li ３＋ａ－ｃ－２ｄ X ２－ａ－ｂ－ｃ－ｄ M1 ａ M2 ｂ M3 ｃ M4 ｄ B ３ O ９ An ion-conducting solid comprising an oxide represented by the formula, wherein the number-average particle size of the ion-conducting solid is 0.01 μm or more and 10.00 μm or less. (wherein X is at least one metallic element selected from the group consisting of La, Pr, Nd, Sm and Eu; M1 is at least one metallic element selected from the group consisting of Mg, Co, Mn, Zn, Ni, Ca, Sr and Ba; M2 is at least one metallic element selected from the group consisting of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, In, Fe, Sc, Ga and Al; M3 is at least one metallic element selected from the group consisting of Zr, Ce, Hf, Sn and Ti; M4 is at least one metallic element selected from the group consisting of V, Nb, Ta, W and Mo.) a is a real number satisfying 0.000 ≤ a ≤ 0.800, b is a real number satisfying 0.000 ≤ b ≤ 1.000, c is a real number satisfying 0.000 ≤ c ≤ 0.800, d is a real number satisfying 0.000 ≤ a + b + c + d < 2.000, except when X and M2 are the same metallic element.

2. The ion-conducting solid according to claim 1, wherein 2-a-b-c-d is 1.000 ≤ 2-a-b-c-d.

3. The ion-conducting solid according to claim 1 or 2, wherein a is 0.000 ≤ a ≤ 0.

400.

4. The ion-conducting solid according to any one of claims 1 to 3, wherein b is 0.000 ≤ b ≤ 0.

800.

5. The ion-conducting solid according to any one of claims 1 to 4, wherein c is 0.000 ≤ c ≤ 0.

400.

6. The ion-conducting solid according to any one of claims 1 to 5, wherein d is 0.000 ≤ d ≤ 0.

400.

7. The ion-conducting solid according to any one of claims 1 to 6, wherein the number-average particle size is 0.01 μm or more and 5.00 μm or less.

8. An all-solid-state battery having at least a positive electrode, a negative electrode, and an electrolyte, wherein at least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte comprises an ion-conducting solid as described in any one of claims 1 to 7.

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