JP6948676B2 - Ion-conducting solid-state and all-solid-state batteries - Google Patents

Description

The present disclosure relates to ionic conductive solid-state and all-solid-state batteries.

Conventionally, lightweight and high-capacity lithium-ion secondary batteries have been installed in mobile devices such as smartphones and laptop computers, and in transportation devices such as electric vehicles and hybrid electric vehicles.
However, since a liquid containing a flammable solvent is used as an electrolyte in the conventional lithium ion secondary battery, there is a concern that the flammable solvent may leak or ignite when the battery is short-circuited. Therefore, in recent years, in order to ensure safety, a secondary battery using an ionic conductive solid as an electrolyte, which is different from a liquid electrolyte, has attracted attention, and such a secondary battery is called an all-solid-state battery.

As the electrolyte used in the all-solid-state battery, solid electrolytes such as oxide-based solid electrolytes and sulfide-based solid electrolytes are widely known. Among them, the oxide-based solid electrolyte is safer than the sulfide-based solid electrolyte because it does not react with moisture in the atmosphere to generate hydrogen sulfide.

By the way, the all-solid-state battery includes 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 arranged between the positive electrode and the negative electrode, and a current collector, if necessary. (The positive electrode active material and the negative electrode active material are also collectively referred to as "electrode active material"). When an all-solid-state battery is manufactured using an oxide-based solid electrolyte, heat treatment is performed in order to reduce the contact resistance between particles of the oxide-based material contained in the solid electrolyte. However, since the conventional oxide-based solid electrolyte requires a high temperature of 900 ° C. or higher for heat treatment, the solid electrolyte and the electrode active material may react with each other to form a high resistance phase. The high resistance phase may lead to a decrease in the ionic conductivity of the ionic conductive solid, which in turn leads to a decrease in the output of the all-solid-state battery.
Examples of the oxide-based solid electrolyte that can be produced by heat treatment at a temperature lower than 900 ° C. include Li _{2 + x} C _1-x B _x O ₃ (Non-Patent Document 1).

Solid State Ionic 288 (2016) 248-252

The present disclosure provides an ionic conductive solid that can be produced by heat treatment at a low temperature and has high ionic conductivity, and an all-solid-state battery having the same.

The ionic conductive solids of the present disclosure include oxides represented by _{the general formula Li 6-x-y-2z} Y _1-x-y-z M1 _x M2 _y M3 _z B ₃ O _9.
(In the formula, M1 and M2 are tetravalent metal elements, M3 is a pentavalent metal element, and x, y, and z are 0.000 ≦ x + y <1.000, 0.000 ≦ z <1. It is a real number that satisfies .000 and 0.000 <x + y + z <1.000.)

In addition, the all-solid-state battery of the present disclosure is
Positive electrode A positive electrode containing an active material and a positive electrode
Negative electrode A negative electrode containing an active material and a negative electrode
With electrolytes
An all-solid-state battery that has at least
At least one selected from the group consisting of the positive electrode, the negative electrode and the electrolyte comprises the ionic conductive solid of the present disclosure.

According to one aspect of the present disclosure, an ionic conductive solid that can be produced by heat treatment at a low temperature and has high ionic conductivity, and an all-solid-state battery having the same can be obtained.

Ion Conductivity A diagram showing the relationship between the ionic conductivity of a solid and the value of x + y + z in the _{general formula Li 6-x-y-2z} Y _1-x-y-z M1 _x M2 _y M3 _z B ₃ O _9. Is. It is a diffraction curve of 2θ = 10 ° to 40 ° obtained by XRD. It is a diffraction curve of 2θ = 27.5 ° to 28.5 ° obtained by XRD. It is a figure which shows the relationship between the ionic conductivity of an ionic conductive solid, and the diffraction peak position measured by XRD.

In the present disclosure, the description of "XX or more and YY or less" or "XX to YY" indicating a numerical range means a numerical range including a lower limit and an upper limit which are end points, unless otherwise specified.
Further, in the present disclosure, the “solid” refers to a substance having a certain shape and volume among the three states of the substance, and for example, a substance in a powder state is also included in the “solid”.

The ionic conductive solids of the present disclosure include oxides represented by _{the general formula Li 6-x-y-2z} Y _1-x-y-z M1 _x M2 _y M3 _z B ₃ O _9.
In the formula, M1 and M2 are tetravalent metal elements, and the valences are the valences of the tetravalent metal elements M1 and M2. Further, in the formula, M3 is a pentavalent metal element, and the valence is the valence carried by the pentavalent metal element M3. Further, in the equation, x, y, and z are real numbers satisfying 0.000 ≦ x + y <1.000, 0.000 ≦ z <1.000, 0.000 <x + y + z <1.000. It should be noted that x and y naturally satisfy 0.000 ≦ x <1.000 and 0.000 ≦ y <1.000, respectively.

The present inventors speculate that the reason why the ionic conductivity is improved in the ionic conductive solid having an oxide represented by the above general formula is as follows.
When a part of Y, which is a trivalent metal element, is replaced with M1, M2, and M3, which are 4- to pentavalent metal elements, the charge balance is adjusted by element substitution between different valences. Li ⁺ is deficient. Since the ^{surrounding Li +} moves to fill the ^{Li +} deficiency, the ionic conductivity is improved.

The ionic conductive solid of the present disclosure preferably has a monoclinic crystal structure. The ion-conductive solid comprises a crystal structure of monoclinic type, replacing at least part of one Y ³⁺ selected from the group consisting than Y ³⁺ is a large metallic element valence M1, M2 and M3 (That is, when 0.000 <x + y + z _{), compared to Li 6} YB ₃ O ₉ (that is, when x = y = z = 0.000) which does not contain any of M1, M2, and M3. By affecting the lattice constant, the lattice volume is also affected, and further, the ionic conductivity can be affected.

In X-ray diffraction analysis using CuKα rays (hereinafter, also simply referred to as “XRD”), the diffraction peak generated near 2θ = 28 ° can change depending on the composition of the above-mentioned ion conductive solid and the like.
In the ionic conductive solid of the present disclosure, in XRD using CuKα ray, 2θ = 27.915 ° to 28.100 °, 27.920 ° to 28.100 °, or 27.930 ° to 28.100. It is preferable to have a diffraction peak in the ° range. More preferably, it has a diffraction peak in the range of 2θ = 27.940 ° to 28.050 °, more preferably it has a diffraction peak in the range of 2θ = 27.980 ° to 28.020 °, and particularly preferably 2θ. = Has a diffraction peak in the range of 27.980 ° to 28.010 °.
The position of the diffraction peak generated near 2θ = 28 ° in XRD using CuKα rays is controlled by adjusting the value of x + y + z in the above general formula, changing the metal element indicated by M1 to M3, and the like. be able to.

The ionic conductive solid of the present disclosure ^{preferably has a lattice volume of 752.00 Å 3} or more, more preferably 752.55 Å ³ or more, still more preferably 753.00 Å ³ or more, and particularly preferably 753.40 Å ³ or more. Is.
The lattice volume is preferably 756.00 Å ³ or less, more preferably 754.50 Å ³ or less, still more preferably 754.00 Å ³ or less, and particularly preferably 753.50 Å ³ or less.
The numerical ranges can be combined arbitrarily. The lattice volume can be, for example, 752.00 Å ^{3 to} 756.00 Å ³ .
The lattice volume of the ionic conductive solid can be controlled by adjusting the value of x + y + z in the above general formula, changing the metal element represented by M1 to M3, and the like.

M1 and M2 in the above general formula are tetravalent metal elements. Further, M3 in the above general formula is a pentavalent metal element.
It can be mentioned that M1 and M2 are at least one metal element independently selected from the group consisting of Zr, Ce and Sn, respectively.
Further, it can be mentioned that M1 and M2 are at least one metal element independently selected from the group consisting of Zr and Ce, respectively. Further, M1 and M2 are at least one metal element independently selected from the group consisting of Ce and Sn, respectively. Further, M1 and M2 are at least one metal element independently selected from the group consisting of Zr and Sn, respectively.
Furthermore, M1 and M2 may be Zr. Further, M1 and M2 may be Ce. Further, M1 and M2 may be Sn.
M3 may be Nb.
As a metal element that replaces a part of Y, an element having an ionic radius close to that of Y is easy to replace, and specifically, Ce ⁴⁺ , Zr ⁴⁺ , Sn ⁴⁺ , Ti ⁴⁺ , Nb ⁵⁺ , Ta ^5+, etc. Can be listed as a candidate. ^{Among them, Ce 4+} , Zr ⁴⁺ , Sn ⁴⁺ , and Nb ⁵⁺ , whose ionic radii are closer to Y, easily replace a part of Y. Among them, Ce ⁴⁺ , Zr ⁴⁺ , and Nb ⁵⁺ are more likely to replace a part of Y.

In the above general formula, x, y, and z are real numbers satisfying 0.000 ≦ x + y <1.000, 0.000 ≦ z <1.000, 0.000 <x + y + z <1.000.

The lower limit of x + y is preferably 0.010 or more, 0.020 or more, 0.030 or more, 0.040 or more, 0.050 or more, 0.060 or more, 0.070 or more, 0.080 or more, 0. .090 or more, 0.100 or more, 0.110 or more, 0.120 or more, 0.130 or more, 0.140 or more, 0.150 or more, 0.200 or more, 0.250 or more, 0.300 or more, 0 .350 or more, 0.400 or more, 0.450 or more or 0.500 or more. The upper limit of x + y is preferably 0.950 or less, 0.900 or less, 0.850 or less, 0.800 or less, 0.790 or less, 0.780 or less, 0.770 or less, 0.760 or less, 0. .750 or less, 0.740 or less, 0.730 or less, 0.720 or less, 0.710 or less, 0.700
Below, 0.690 or less, 0.680 or less, 0.670 or less, 0.660 or less, 0.650 or less, 0.640 or less, 0.630 or less, 0.620 or less, 0.610 or less or 0.600 It is as follows. Further, the upper limit of x + y may be less than 0.800. Further, the lower limit of x + y may be more than 0.000. The numerical ranges can be combined arbitrarily.

The lower limit of z is preferably 0.010 or more, 0.020 or more, 0.030 or more, 0.040 or more, 0.050 or more, 0.060 or more, 0.070 or more, 0.080 or more, 0. .090 or more, 0.100 or more, 0.110 or more, 0.120 or more, 0.130 or more, 0.140 or more, 0.150 or more, 0.200 or more, 0.250 or more, 0.300 or more, 0 .350 or more, 0.400 or more, 0.450 or more or 0.500 or more. The upper limit of z is preferably 0.950 or less, 0.900 or less, 0.850 or less, 0.800 or less, 0.790 or less, 0.780 or less, 0.770 or less, 0.760 or less, 0. .750 or less, 0.740 or less, 0.730 or less, 0.720 or less, 0.710 or less, 0.700 or less, 0.690 or less, 0.680 or less, 0.670 or less, 0.660 or less, 0 .650 or less, 0.640 or less, 0.630 or less, 0.620 or less, 0.610 or less or 0.600 or less. Further, the upper limit value of z may be less than 0.800. Further, the lower limit of z may be more than 0.000. The numerical ranges can be combined arbitrarily.

The ionic conductive solid of the present disclosure can be, for example, the following embodiments, but is not limited to these embodiments.
(1)
y and z satisfy y = z = 0.000,
M1 is Zr and
It is preferable that x satisfies 0.000 <x <1.000 (preferably 0.000 <x <0.800).
(2)
y and z satisfy y = z = 0.000,
M1 is Ce,
It is preferable that x satisfies 0.000 <x <1.000 (preferably 0.000 <x <0.800).
(3)
y and z satisfy y = z = 0.000,
M1 is Sn and
It is preferable that x satisfies 0.000 <x <1.000 (preferably 0.000 <x <0.800).
(4)
z satisfies z = 0.000,
M1 is Zr, M2 is Ce,
It is preferable that x + y satisfies 0.000 <x + y <1.000 (preferably 0.000 <x + y <0.800).
(5)
z satisfies z = 0.000,
M1 is Zr, M2 is Sn,
It is preferable that x + y satisfies 0.000 <x + y <1.000 (preferably 0.000 <x + y <0.800).
(6)
z satisfies z = 0.000,
M1 is Ce, M2 is Sn,
x + y is 0.000 <x + y <1.000 (preferably 0.000 <x + y <0.8)
00) should be satisfied.
(7)
x and y satisfy x = y = 0.000,
M3 is Nb and
It is preferable that z satisfies 0.000 <z <1.000 (preferably 0.000 <z <0.800).

Next, the method for producing the ionic conductive solid of the present disclosure will be described.
The method for producing an ionic conductive solid of the present disclosure can be, for example, the following aspects, but is not limited thereto.
A method for producing an ionic conductive solid containing an oxide represented by the general formula Li _6-x-y-2z Y _1-x-y-z M1 _x M2 _y M3 _z B ₃ O _9.
It is possible to have a calcining step of heating the oxide at a temperature below the melting point of the oxide.
(In the formula, M1 and M2 are tetravalent metal elements, M3 is a pentavalent metal element, and x, y, and z are 0.000 ≦ x + y <1.000, 0.000 ≦ z <1. It is a real number that satisfies .000 and 0.000 <x + y + z <1.000.)

The method for producing an ionic conductive solid of the present disclosure includes (1) a calcination step for producing an oxide represented by the above general formula, and (2) a temperature at which the obtained oxide is lower than the melting point of the oxide. The main firing step of heat-treating in the above can be included.
Hereinafter, the method for producing an ionic conductive solid of the present disclosure including the above-mentioned temporary firing step and the above-mentioned main firing step will be described in detail, but the present disclosure is not limited to the following manufacturing method.

(1) Temporary firing step In the temporary firing step, for example, Li _6-x-y-2z Y _1-x-y-z M1 _x M2 _y M3 _z B ₃ O ₉ (however, M1 and M2 are tetravalent metals. It is an element, M3 is a pentavalent metal element, and x, y, and z are 0.000 ≦ x + y <1.000, 0.000 ≦ z <1.000, 0.000 <x + y + z <1.000. _{Raw materials such as chemical reagent grade Li 3} BO ₃ , H ₃ BO ₃ , Y ₂ O ₃ , ZrO ₂ , CeO ₂ , Nb ₂ O ₅ are weighed in a chemical quantity so that the real number) is satisfied. , Mix.
The apparatus used for mixing is not particularly limited, but a pulverizing mixer such as a planetary ball mill can be used. The material and capacity of the container used for mixing, and the material and diameter of the ball are not particularly limited, and can be appropriately selected according to the type and amount of the raw material used. As an example, a 45 mL container made of zirconia and a 5 mm diameter ball made of zirconia can be used. The conditions of the mixing treatment are not particularly limited, but can be, for example, a rotation speed of 50 rpm to 2000 rpm and a time of 10 minutes to 60 minutes.
After obtaining a mixed powder of each of the above raw materials by the mixing treatment, the obtained mixed powder is pressure-molded to obtain pellets. Here, as the pressure molding method, known pressure molding methods such as a cold uniaxial molding method and a cold hydrostatic pressure molding method can be used. The conditions for pressure molding in the tentative firing step are not particularly limited, but can be, for example, a pressure of 100 MPa to 200 MPa.
The obtained pellets may be calcined at about 400 ° C. to 700 ° C. (for example, 650 ° C.) using an atmospheric calcining device or the like to perform solid phase synthesis. If the temperature is in this range, solid-phase synthesis can be sufficiently performed. The time of the tentative firing step is not particularly limited, but can be, for example, about 700 minutes to 750 minutes (for example, 720 minutes).
The obtained calcined product is an oxide represented by _{the above general formula Li 6-x-y-2z} Y _1-x-y-z M1 _x M2 _y M3 _z B ₃ O _9. The calcined powder can also be obtained by pulverizing the calcined product (oxide) using a mortar / pestle or a planetary mill.

(2) Main firing step In the main firing step, at least one selected from the group consisting of the temporary fired body and the temporary fired powder obtained in the temporary firing step is pressure-molded and main-baked to obtain a sintered body. The obtained sintered body is an ionic conductive solid containing an oxide represented by _{the general formula Li 6-x-y-2z} Y _1-x-y-z M1 _x M2 _y M3 _z B ₃ O _9. ..
The pressure molding and the main firing may be performed at the same time by using discharge plasma sintering (hereinafter, also simply referred to as “SPS”) or a hot press, and the pellets are prepared by cold uniaxial molding and then the air atmosphere. The main firing may be performed in an oxidizing atmosphere or a reducing atmosphere. Under such conditions, an ionic conductive solid having high ionic conductivity can be obtained without causing melting by heat treatment. The conditions for pressure molding in this firing step are not particularly limited, but can be, for example, a pressure of 10 MPa to 100 MPa.
The main firing temperature is lower than the melting point of the oxide represented by _{the general formula Li 6-x-y-2z} Y _1-x-y-z M1 _x M2 _y M3 _z B ₃ O _9. The temperature at the time of the main firing is preferably less than 700 ° C., more preferably 680 ° C. or lower, still more preferably 670 ° C. or lower, and particularly preferably 660 ° C. or lower. The lower limit of the temperature is not particularly limited, and the lower the temperature, the more preferable, but it is, for example, 500 ° C. or higher. The numerical range can be arbitrarily combined, and can be, for example, a range of 500 ° C. or higher and lower than 700 ° C. Within this range, it is possible to prevent the temporarily fired body from melting or decomposing in the main firing step, and a sufficiently sintered sintered body can be obtained.
The time of the main firing step can be appropriately changed depending on the temperature of the main firing and the like, but is preferably 24 hours or less, and may be 1 hour or less. The time of the main firing step may be, for example, 5 minutes or more.

The method for cooling the sintered body (ion conductive solid) obtained in this firing step is not particularly limited, and natural cooling (cooling in the furnace), rapid cooling, or rapid cooling may be performed. It may be cooled more gradually than natural cooling, or it may be maintained at a certain temperature during cooling.

Next, the all-solid-state battery of the present disclosure will be described.
An all-solid-state battery generally collects 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 arranged between the positive electrode and the negative electrode, and if necessary. Has a body.
The all-solid-state battery of the present disclosure is
Positive electrode A positive electrode containing an active material and a positive electrode
Negative electrode A negative electrode containing an active material and a negative electrode
With electrolytes
An all-solid-state battery that has at least
At least one selected from the group consisting of the positive electrode, the negative electrode and the electrolyte comprises the ionic conductive solid of the present disclosure.
Here, the above-mentioned "including" means having as a component, an element, and a property. For example, both the case where the electrode active material is contained in the electrode and the case where the electrode active material is applied to the electrode surface corresponds to the above-mentioned "contains".

The all-solid-state battery of the present disclosure may be a bulk type battery or a thin film battery. The specific shape of the all-solid-state battery of the present disclosure is not particularly limited, and examples thereof include a coin type, a button type, a sheet type, and a laminated type.

The all-solid-state battery of the present disclosure has an electrolyte. Further, in the all-solid-state battery of the present disclosure, it is preferable that at least the electrolyte contains the ionic conductive solid of the present disclosure.
The solid electrolyte in the all-solid-state battery of the present disclosure may consist of the ionic conductive solid of the present disclosure, or may contain other ionic conductive solids. The other ionic conductive solid is not particularly limited, and may include ionic conductive solids usually used in all-solid-state batteries, such as LiI, Li ₃ PO ₄ , Li ₇ La ₃ Zr ₂ O _{12, and the} like. good. The content of the ionic conductive solid of the present disclosure in the electrolyte in the all-solid-state battery of the present disclosure is preferably 25% by mass or more, more preferably 50% by mass or more, still more preferably 75% by mass or more. Yes, especially preferably 100% by mass.

The all-solid-state battery of the present disclosure has a positive electrode containing a positive electrode active material. The positive electrode may contain a positive electrode active material and an ionic conductive solid of the present disclosure. As the positive electrode active material, a known positive electrode active material such as a sulfide containing a transition metal element or an oxide containing lithium and a transition metal element can be used without particular limitation.
Further, the positive electrode may contain a binder, a conductive agent and the like. Examples of the binder include polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol and the like. Examples of the conductive agent include natural graphite, artificial graphite, acetylene black, ethylene black and the like.

The all-solid-state battery of the present disclosure has a negative electrode containing a negative electrode active material. The negative electrode may contain a negative electrode active material and an ionic conductive solid of the present disclosure. As the negative electrode active material, an inorganic compound such as lithium, a lithium alloy or a tin compound, a carbonaceous material capable of absorbing and releasing lithium ions, and a known negative electrode active material such as a conductive polymer can be used without particular limitation.
Further, the negative electrode may contain a binder, a conductive agent and the like. As the binder and the conductive agent, the same ones as those mentioned for the positive electrode can be used.

The positive electrode and the negative electrode can be obtained by a known method such as mixing, molding, and heat-treating the raw materials. As a result, it is considered that the ionic conductive solid enters the gap between the electrode active materials and the like, and it becomes easy to secure the conduction path of the lithium ion. Since the ionic conductive solid of the present disclosure can be produced by heat treatment at a lower temperature than that of the prior art, it is considered that the formation of a high resistance phase formed by the reaction between the ionic conductive solid and the electrode active material can be suppressed.

The positive electrode and the negative electrode may have a current collector. As the current collector, known current collectors such as aluminum, titanium, stainless steel, nickel, iron, calcined carbon, conductive polymer, and conductive glass can be used. In addition, for the purpose of improving adhesiveness, conductivity, oxidation resistance, etc., an aluminum, copper, or the like whose surface is treated with carbon, nickel, titanium, silver, or the like can be used as a current collector.

The all-solid-state battery of the present disclosure can be obtained by a known method such as laminating a positive electrode, a solid electrolyte, and a negative electrode, molding, and heat-treating. Since the ionic conductive solid of the present disclosure can be produced by heat treatment at a lower temperature than that of the prior art, it is considered that the formation of a high resistance phase generated by the reaction between the ionic conductive solid and the electrode active material can be suppressed, and the output It is considered that an all-solid-state battery having excellent characteristics can be obtained.

Next, the composition and the method for measuring each physical property according to the present disclosure will be described.
-Identification of M1 to M3 and analysis method of x, y, z For composition analysis of ionic conductive solids, wavelength dispersive fluorescent X-ray analysis (hereinafter, also referred to as XRF) using a sample solidified by a pressure molding method. It is done by). However, when analysis is difficult due to the particle size effect or the like, it is advisable to vitrify the ionic conductive solid by the glass bead method and perform composition analysis by XRF. In XRF, when the peak of yttrium and the peak of tetravalent metal or pentavalent metal overlap, it is advisable to perform composition analysis by inductively coupled high frequency plasma emission spectroscopy (ICP-AES).
In the case of XRF, the analyzer uses ZSX Primus II manufactured by Rigaku Co., Ltd. The analysis conditions are as follows: Rh is used for the anode of the X-ray tube, a vacuum atmosphere, an analysis diameter of 10 mm, an analysis range of 17 deg to 81 deg, a step of 0.01 deg, and a scan speed of 5 sec / step. Further, when measuring a light element, it is detected by a proportional counter, and when measuring a heavy element, it is detected by a scintillation counter.
Elements are identified based on the peak position of the spectrum obtained by XRF, and the molar concentration ratios Y / M1, Y / M2 and Y / are derived from the counting rate (unit: cps), which is the number of X-ray photons per unit time. M3 is calculated to obtain x, y, and z.
If one type of tetravalent metal is identified and a pentavalent metal is not detected, the tetravalent metal is assigned to M1 in the general formula.

-Measurement of X-ray diffraction peak and calculation of lattice volume D8 ADVANCE manufactured by BrukerAXS Co., Ltd. is used for X-ray diffraction analysis of an ion conductive solid.
After putting the powder obtained by crushing the ionic conductive solid with a mortar and pestle into a holder, pressing it from above with a glass flat plate and laying it flat is used as an analysis sample, and X-ray diffraction is performed using a CuKα radiation source. Perform analysis (XRD).
The temperature is room temperature (25 ° C.), the analysis range is 10 deg to 70 deg, the step is 0.007, and the scan speed is 0.1 step / sec.
In the diffraction curve obtained by XRD, 2θ of the peak top generated at 2θ = 28.000 ± 0.200 deg derived from _{Li 6} YB ₃ O _{9 is determined as the peak position.}
The lattice volume of the crystal phase is calculated using the diffraction curve obtained by XRD and the structural analysis software TOPAS manufactured by BrukerAXS Co., Ltd. The lattice volume is calculated by fitting and analyzing the diffraction curve obtained by XRD and the diffraction pattern of the crystal phase of the monoclinic crystal structure by TOPAS.

Hereinafter, an example in which the ionic conductive solid of the present disclosure is specifically prepared and evaluated as a sintered body will be described as an example. The present disclosure is not limited to the following examples.

[Example 1]
-Temporary firing process Li ₃ BO ₃ (manufactured by Toyoshima Seisakusho, purity 99.9% by mass), H ₃ BO ₃ (manufactured by Kanto Chemical Co., Ltd., purity 99.5%), Y ₂ O ₃ (manufactured by Shinetsu Chemical Industry Co., Ltd., purity 99. 9% by mass) and ZrO ₂ (manufactured by Shin Nippon Denko, purity 99.9%) are used as raw materials, and each raw material is chemically _converted to Li 5.975 Y _0.975 Zr _0.025 B ₃ O _9. It was weighed by stoichiometry and mixed with a planetary mill P-7 manufactured by Fritsch at a disk rotation speed of 300 rpm for 30 minutes. A zirconia φ5 mm ball and a 45 mL container were used for the planetary mill.
Then, the mixed powder was cold uniaxially molded at 147 MPa using a 100 kN electric press device P3052-10 manufactured by NPM System, and calcined in an atmospheric atmosphere. The heating temperature was 650 ° C. and the holding time was 720 minutes.
The obtained calcined product was pulverized with a planetary mill P-7 manufactured by Fritsch at a disk rotation speed of 230 rpm for 180 minutes to prepare a calcined powder.
-Main firing step The temporary firing powder obtained above is molded and main-baked using a discharge plasma sintering machine SPS-625 manufactured by Fuji Denpa Kogyo Co., Ltd. (hereinafter, also simply referred to as "SPS"). A sintered body of the above was prepared. The heating temperature was 630 ° C., the pressure was 30 MPa, and the holding time was 10 minutes.

[Examples 2 to 9]
-The calcined product and the calcined powder were prepared in the same process as in Example 1 except that each of the above raw materials was weighed by stoichiometry so that the calcined step x had the values shown in Table 1.
-Main firing step The temporary firing powder obtained above is molded by discharge plasma sintering (SPS) and main fired to be carried out in Example 2.
A sintered body of ~ 9 was prepared. The heating temperature was as shown in Table 1, the pressure was 30 MPa, and the holding time was 10 minutes.

[Example 10]
-The calcined product and the calcined powder were prepared in the same process as in Example 1 except that each of the above raw materials was weighed by stoichiometry so that the calcined step x had the values shown in Table 1.
-Main firing step The temporarily fired powder obtained above was molded and main fired to prepare a sintered body of Example 10. The main firing was carried out in an atmospheric atmosphere, the heating temperature was 650 ° C., and the holding time was 720 minutes.

[Example 11]
-Temporary firing process Li ₃ BO ₃ (manufactured by Toyoshima Seisakusho, purity 99.9% by mass), H ₃ BO ₃ (manufactured by Kanto Chemical Co., Ltd., purity 99.5%), Y ₂ O ₃ (manufactured by Shin-Etsu Chemical Co., Ltd., purity 99. 9% by mass) and CeO ₂ (manufactured by Shin-Etsu Chemical Co., Ltd., purity 99.9%) are used as raw materials, and each raw material is chemically _{processed so} as to have Li 5.900 Y _0.900 Ce _0.100 B ₃ O _9. A tentatively fired body and a tentatively fired powder were prepared in the same steps as in Example 1 except that they were weighed in a quantitative quantity.
-Main firing step The temporary firing powder obtained above was molded by discharge plasma sintering (SPS) and main fired to prepare a sintered body of Example 11. The heating temperature was 660 ° C., the pressure was 30 MPa, and the holding time was 10 minutes.

[Example 12]
-Temporary firing process Li ₃ BO ₃ (manufactured by Toyoshima Seisakusho, purity 99.9% by mass), H ₃ BO ₃ (manufactured by Kanto Chemical Co., Ltd., purity 99.5%), Y ₂ O ₃ (manufactured by Shinetsu Chemical Industry Co., Ltd., purity 99. Using 9% by mass) and Nb ₂ O ₅ (manufactured by Mitsui Mining & Smelting Co., Ltd., purity 99.9%) as raw materials, each raw material becomes _{Li 5.800} Y _0.900 Nb _0.100 B ₃ O _9. Was weighed by a chemical amount, and a calcined product and a calcined powder were prepared in the same steps as in Example 1.
-Main firing step The temporary firing powder obtained above was molded by discharge plasma sintering (SPS) and main fired to prepare a sintered body of Example 12. The heating temperature was 600 ° C., the pressure was 30 MPa, and the holding time was 10 minutes.

[Example 13]
-Temporary firing process Li ₃ BO ₃ (manufactured by Toyoshima Seisakusho, purity 99.9% by mass), H ₃ BO ₃ (manufactured by Kanto Chemical Co., Ltd., purity 99.5%), Y ₂ O ₃ (manufactured by Shinetsu Chemical Industry Co., Ltd., purity 99. 9% by mass), ZrO ₂ (manufactured by Shin Nippon Denko, purity 99.9%) and CeO ₂ (manufactured by Shin-Etsu Chemical Co., Ltd., purity 99.9%) as raw materials, Li _5.875 Y _0.875 Zr _{0 A} calcined product and a calcined powder were prepared in the same process as in Example 1 except that each raw material was weighed by a chemical amount so as to be 100 Ce _0.025 B ₃ O _9.
-Main firing step The temporarily fired powder obtained above was molded and main fired to prepare a sintered body of Example 13. The main firing was carried out in an atmospheric atmosphere, the heating temperature was 650 ° C., and the holding time was 720 minutes.

[Example 14]
-The calcined product and the calcined powder were prepared in the same process as in Example 11 except that each of the above raw materials was weighed by stoichiometry so that the calcined step x had the values shown in Table 1.
-Main firing step The temporarily fired powder obtained above was molded and main fired to prepare a sintered body of Example 14. The main firing was carried out in an atmospheric atmosphere, the heating temperature was 650 ° C., and the holding time was 720 minutes.

[Example 15]
-Temporary firing process Li ₃ BO ₃ (manufactured by Toyoshima Seisakusho, purity 99.9% by mass), H ₃ BO ₃ (manufactured by Kanto Chemical Co., Ltd., purity 99.5%), Y ₂ O ₃ (manufactured by Shinetsu Chemical Industry Co., Ltd., purity 99. 9% by mass) and SnO ₂ (manufactured by Mitsuwa Chemical Co., Ltd., purity 99.7%) are used as raw materials, and each raw material is _adjusted to Li 5.975 Y _0.975 Sn _0.025 B ₃ O _9. A calcined product and a calcined powder were prepared in the same steps as in Example 1 except that the calcined product was weighed by a chemical quantity and the heating temperature in the calcining was set to 600 ° C.
-Main firing step The temporary firing powder obtained above was molded by discharge plasma sintering (SPS) and main fired to prepare a sintered body of Example 15. The heating temperature was as shown in Table 1, the pressure was 30 MPa, and the holding time was 10 minutes.

[Examples 16 to 17]
-The same process as in Example 1 except that each of the above raw materials was weighed in a chemical quantity so that the calcination step x had the values shown in Table 1 and the heating temperature in the calcination was set to 600 ° C. A calcined body and a calcined powder were prepared.
-Main firing step The temporary firing powder obtained above was molded by discharge plasma sintering (SPS) and main fired to prepare sintered bodies of Examples 16 to 17. The heating temperature was as shown in Table 1, the pressure was 30 MPa, and the holding time was 10 minutes.

[Examples 18 to 19]
-The same as in Example 1 except that each of the above raw materials was weighed by a chemical amount so that the temporary firing steps x and y were the values shown in Table 1, and the heating temperature in the temporary firing was set to 600 ° C. A calcined body and a calcined powder were prepared in the process.
-Main firing step The temporarily fired powder obtained above was molded and main fired to prepare sintered bodies of Examples 18 to 19. The main firing was carried out in an atmospheric atmosphere, the heating temperature was 600 ° C., and the holding time was 720 minutes.

[Example 20]
-The same process as in Example 1 except that each of the above raw materials was weighed in a chemical quantity so that the calcination step x had the values shown in Table 1 and the heating temperature in the calcination was set to 600 ° C. A calcined body and a calcined powder were prepared.
-Main firing step The temporary firing powder obtained above was molded by discharge plasma sintering (SPS) and main fired to prepare a sintered body of Example 20. The heating temperature was as shown in Table 1, the pressure was 30 MPa, and the holding time was 10 minutes.

[Examples 21 to 22]
-The same as in Example 1 except that each of the above raw materials was weighed by a chemical amount so that the temporary firing steps x and y were the values shown in Table 1, and the heating temperature in the temporary firing was set to 600 ° C. A calcined body and a calcined powder were prepared in the process.
-Main firing step The temporarily fired powder obtained above was molded and main fired to prepare the sintered body of Examples 21 to 22. The main firing was carried out in an atmospheric atmosphere, the heating temperature was 650 ° C., and the holding time was 720 minutes.

[Example 23]
-The calcined product and the calcined powder were prepared in the same process as in Example 1 except that each of the above raw materials was weighed by stoichiometry so that the calcined step z became the value shown in Table 1.
-Main firing step The temporary firing powder obtained above was molded by discharge plasma sintering (SPS) and main fired to prepare a sintered body of Example 23. The heating temperature was as shown in Table 1, the pressure was 30 MPa, and the holding time was 10 minutes.

[Comparative Example 1]
-Temporary firing process Li ₃ BO ₃ (manufactured by Toyoshima Seisakusho, purity 99.9% by mass), H ₃ BO ₃ (manufactured by Kanto Chemical Co., Ltd., purity 99.5%), and Y ₂ O ₃ (manufactured by Shinetsu Chemical Industry Co., Ltd., purity 99%). .9% by mass) was used as a _{raw material, and each raw material was weighed by stoichiometry so as to be Li 6} YB ₃ O _9, and a temporary calcined product and a temporary calcined powder were prepared in the same process as in Example 1. bottom.
-Main firing step The temporary firing powder obtained above was molded by discharge plasma sintering (SPS) and main fired to prepare a sintered body of Comparative Example 1. The heating temperature was 700 ° C., the pressure was 30 MPa, and the holding time was 10 minutes.

[Comparative Example 2]
-Temporary firing process Li ₃ BO ₃ (manufactured by Toyoshima Seisakusho, purity 99.9% by mass), H ₃ BO ₃ (manufactured by Kanto Chemical Co., Ltd., purity 99.5%), ZrO ₂ (manufactured by Shin Nihon Denko, purity 99.9%) ) And CeO ₂ (manufactured by Shin-Etsu Chemical Co., Ltd., purity 99.9%) as raw materials, and each raw material is chemically quantitatively _{adjusted to Li 5.000} Zr 0.800 Ce _0.200 B ₃ O _9. A calcined product and a calcined powder were prepared in the same steps as in Example 1 except that they were weighed.
-Main firing step The temporarily fired powder obtained above was molded and main fired to prepare a sintered body of Comparative Example 2. The main firing was carried out in an atmospheric atmosphere, the heating temperature was 550 ° C., and the holding time was 720 minutes.

For the sintered bodies of Examples 1 to 23 and Comparative Examples 1 and 2, composition analysis, X-ray diffraction peak measurement, and lattice volume calculation were performed by the above methods. In addition, the ionic conductivity was measured by the following method. The method for measuring the ionic conductivity will be described below. The obtained evaluation results are shown in Table 1.

-Measurement of ionic conductivity In the flat plate-shaped sintered body obtained by this firing, two surfaces facing each other in parallel and having a large area were polished with sandpaper. The dimensions of the flat plate-shaped sintered body can be, for example, 0.9 cm × 0.9 cm × 0.05 cm, but the dimensions are not limited thereto. Polishing is first done with # 500 for 15 to 30 minutes, then with # 1000 for 10 to 20 minutes, and finally with # 2000 for 5 to 10 minutes. If it is completed.
Then, gold was formed on the polished surface of the sintered body using a sputtering apparatus SC-701MkII ADVANCE manufactured by Sanyu Electronics. As the film forming conditions, the process gas was Ar, the degree of vacuum was 2 Pa to 5 Pa, and the film forming time was 5 minutes. Then, the AC impedance of the measurement sample was measured.
An impedance / gain phase analyzer SI1260 and a dielectric interface system 1296 (both manufactured by Solartron) were used for impedance measurement, and the measurement conditions were a temperature of 27 ° C., an amplitude of 20 mV, and a frequency of 1 MHz to 0.1 Hz.
The resistance of the sintered body was calculated using the Nyquist plot obtained by impedance measurement and the AC analysis software ZVIEW manufactured by Scribner. An equivalent circuit corresponding to the measurement sample was set in ZVIEW, and the resistance of the sintered body was calculated by fitting and analyzing the equivalent circuit and the Nyquist plot. Using the calculated resistance, the thickness of the sintered body, and the electrode area, the ionic conductivity was calculated from the following formula.
Ion conductivity (S / cm) = Sintered body thickness (cm) / (Sintered body resistance (Ω) x Electrode area (cm ² ))

-Results Table 1 shows the stoichiometric quantities of the raw materials for producing the sintered bodies of Examples 1 to 23 and Comparative Examples 1 and 2 (general formula Li _6-xy-2z Y _{1-xy). -z M1 x M2 y M3 z B} 3 O 9 in M1, M2 and M3 are metal showing elements, and, x, y values and z), summarizing the heating method and the heating temperature. In addition, Table 1 summarizes the diffraction peak positions, lattice volumes, and ionic conductivity of each of the sintered bodies obtained in Examples 1 to 23 and Comparative Examples 1 and 2.
As a result of the above composition analysis, it was confirmed that the sintered bodies of Examples 1 to 23 and Comparative Example 1 all had the composition according to the stoichiometric amount of the raw material shown in Table 1. Further, the sintered bodies of Examples 1 to 23 were ionic conductive solids showing high ionic conductivity even when fired at a temperature of less than 700 ° C. On the other hand, the main crystal structure of the sintered body of Comparative Example 2 was a mixture of _{ZrO 2} and CeO _{2 used as raw materials.}
Further, FIG. 1 shows the relationship between the ionic conductivity of the ionic conductive solid and the value of x + y + z in the general formula. Furthermore, FIG. 4 shows the relationship between the ionic conductivity of the ionic conductive solid and the diffraction peak position measured by XRD.

表中、ピーク位置及び格子体積の列における「−」は、データ未取得であることを示す。また、ピーク位置の列における「※１」は、２θ＝２７．５°〜２８．５°の範囲内にピークがみられなかったことを示す。ピーク位置の列における「※２」は、Ｌｉ_６ＹＢ_３Ｏ_９で表される酸化物のピークがみられなかったことを示す。イオン伝導率の列における「※３」は、高抵抗であってイオン伝導率の測定が不可能であったことを示す。

In the table, "-" in the column of peak position and lattice volume indicates that data has not been acquired. Further, "* 1" in the row of peak positions indicates that no peak was observed in the range of 2θ = 27.5 ° to 28.5 °. “* 2” in the peak position column indicates that the peak of the oxide represented by _{Li 6} YB ₃ O _{9 was not observed.} "* 3" in the ionic conductivity column indicates that the ionic conductivity could not be measured due to the high resistance.

Figures 2 and 3 show the diffraction curves obtained by XRD. FIG. 2 shows a range of 2θ = 10 ° to 40 °, and FIG. 3 shows a range of 2θ = 27.5 ° to 28.5 °. From FIG. 2, it was found that the main crystal structures of Examples 1 to 11, 13 to 17, 21 to 23 were monoclinic _{structures of Li 6} YB ₃ O _9.
Further, from FIG. 3, it was confirmed that the peak position near 2θ = 28.000 ° in Examples 1 to 11, 13 to 17, 21 and 22 was shifted to a higher angle side than 27.925 ° in Comparative Example 1. did it. Further, from FIG. 3, it was confirmed that the peak position near 2θ = 28.000 ° in Example 23 was shifted to a lower angle side than 27.925 ° in Comparative Example 1. The present inventors speculate that these are caused by at least one metal element selected from the group consisting of M1, M2 and M3 substituting a part of the trivalent metal Y.

Claims (6)

An ionic conductive solid containing an oxide represented by the general formula Li _6-x-y-2z Y _1-x-y-z M1 _x M2 _y M3 _z B ₃ O _9.
(In the formula, M1 and M2 are at least one metal element independently selected from the group consisting of Zr, Ce and Sn, respectively , M3 is Nb , and x, y and z are 0.000 ≦ x + y. <1.000, 0.000 ≦ z <1.000, 0.000 <x + y + z <1.000 is a real number that satisfies.) The y and the z satisfy y = z = 0.000,
The M1 is Zr,
The ionic conductive solid according to claim 1, wherein x satisfies 0.000 <x <1.000. The ionic conductive solid according to claim 1 or 2 , which has a diffraction peak in the range of 2θ = 27.930 ° to 28.100 ° in X-ray diffraction analysis using CuKα rays. The ionic conductive solid according to any one of claims 1 to 3 , wherein the lattice volume is 752.00 Å ^{3 to} 756.00 Å ^3. Positive electrode A positive electrode containing an active material and a positive electrode
Negative electrode A negative electrode containing an active material and a negative electrode
With electrolytes
An all-solid-state battery that has at least
An all-solid-state battery, wherein at least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte contains the ionic conductive solid according to any one of claims 1 to 4. The all-solid-state battery according to claim 5 , wherein at least the electrolyte contains the ionic conductive solid.

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