JPH0680462A - Solid electrolyte - Google Patents

Abstract

PURPOSE:To provide a solid electrolyte having dense structure and high electrical conductivity. CONSTITUTION:Powder produced by finely pulverizing sintered ceramic electrolytes having high ionic conductivity such as Li1.4Ti1.6In0.4P3O12, Li2Zr(PO4)2 Na3Zr2Si2PO12, Na2Zr(PO4)2, Ag3Zr2Si2 and Ag2Zr(po4 is mixed <=40wt.% of powder produced by finely pulverizing the same kind of sintered electrolyte such as li4Sm2Si2O9, Na4Gd2Si2O9 and Ag2SiO3 having ionic conductivity and high content of vitreous component and the mixed powder is calcined at a relatively low temperature (900-1100 deg.C) to obtain the objective solid electrolyte.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte, and more particularly to a solid electrolyte composed of a dense ceramic having a structure produced by sintering.

[0002]

2. Description of the Related Art Various solid electrolytes utilizing electric conduction by ions are known and include alkali metal ions and Ag.
Conventional solid electrolytes utilizing the conduction of ions include Li
_1.4 Ti _1.6 In _0.4 P ₃ O ₁₂ , Li ₂ Zr (PO ₄ ) ₂
, Β-Al ₂ O ₃ , Na ₃ Zr ₂ Si ₂ PO ₁₂ , Na ₂
Zr (PO ₄ ) ₂ , Ag ₃ Zr ₂ Si ₂ PO ₁₂ , Ag ₂
Zr (PO ₄ ) _{2 and the} like are known and used for various applications such as sensors and batteries.

[0003]

Among the solid electrolytes that conduct alkali metal ions and Ag ions, the ceramic electrolytes having the above-described compositions that exhibit high ionic conductivity have poor sinterability and, when heated to high temperatures, Alkali metal ion scattering, reaction with firing jig due to vitrification and A
Problems such as liberation of g ions as metallic Ag occur,
There is a drawback that it is difficult to obtain a solid electrolyte having a high density and a high ionic conductivity.

[0004]

The present invention is a solid obtained by adding 40 wt% or less of an electrolyte containing a large amount of a glass component, which is a conductor of the same type of ion, to a ceramic electrolyte having a high conductivity as a main component and sintering the solid. It is an electrolyte. In the ceramics having a large glass component in the present invention, a broad peak due to the presence of the glass component is observed at around 2θ = 20 to 40 ° by measurement by X-ray diffraction using CuKα ray, and further by an electron microscope, the grain size of the particles is It is a substance in which many glassy components whose fields cannot be clearly distinguished are observed.

In order to produce the solid electrolyte of the present invention, 40 powders obtained by finely pulverizing a ceramic electrolyte sintered body having a high ionic conductivity and finely pulverizing ceramics containing a glass component of the same kind as the ionic conductor are used. It is obtained by adding and mixing in an amount of not more than wt% and then firing at 900 to 1100 ° C.

[0006]

[Function] Li _1.4 Ti _1.6 In _0.4 P ₃ O ₁₂ , Li ₂ which is a ceramic electrolyte sintered body having high ionic conductivity
Zr (PO ₄ ) ₂ , Na ₃ Zr ₂ Si ₂ PO ₁₂ , Na ₂
Zr (PO ₄ ) ₂ , Ag ₃ Zr ₂ Si ₂ PO ₁₂ , Ag ₂
Li ₄ Sm ₂ Si ₂ O ₉ , Na ₄ Gd ₂ Si ₂ O ₉ , which is an ionic conductor of the same kind and an electrolyte sintered body having many glass components in powders obtained by finely pulverizing Zr (PO ₄ ) _2, etc., respectively.
Each powder of finely crushed Ag ₂ SiO ₃ etc.
The solid electrolyte of the present invention obtained by adding and mixing less than or equal to mass% and firing at a relatively low temperature of 900 to 1100 ° C. is dense and retains the high ionic conductivity of the main component ceramic electrolyte.

[0007]

【Example】

Example 1 Li _1.4 Ti _1.6 In _0.4 P ₃ O ₁₂ and Li ₄ Sm ₂ Si ₂ O ₉ ,
Na ₃ Zr ₂ Si ₂ PO ₁₂ and _{Na 4 Gd 2 Si 2 O 9} , Ag 3 Z
The solid electrolytes obtained from r ₂ Si ₂ PO ₁₂ and Ag ₂ SiO ₃ will be described.

Li _1.4 Ti _1.6 In _0.4 P ₃ O ₁₂ , Li ₄
Sm ₂ Si ₂ O ₉ , Na ₃ Zr ₂ Si ₂ PO ₁₂ , Na ₄
Gd ₂ Si ₂ O ₉ and Ag ₂ SiO ₃ are mixed with the oxides and carbonates of the respective components so as to have their respective compositions, kneaded, temporarily molded, and before reaction with the setter for firing is recognized. Firing is performed at a temperature of 800 to 1300 ° C., but 1200 for Li _1.4 Ti _1.6 In _0.4 P ₃ O _12.
℃, 1100 ℃ for Li ₄ Sm ₂ Si ₂ O ₉ , Na ₃
For Zr ₂ Si ₂ PO ₁₂ , 1300 ° C., Na ₄ Gd ₂ S
The temperature is preferably 1100 ° C. for i ₂ O ₉ and 800 ° C. for Ag ₂ SiO ₃ .

The obtained fired body is finely pulverized to obtain each electrolyte powder. The Ag ₃ Zr ₂ Si ₂ PO ₁₂ powder has the above N content.
After a ₃ Zr ₂ Si ₂ PO ₁₂ powder and AgNO ₃ powder were mixed and Na and Ag were ion-exchanged at 300 ° C. in a crucible, NaNO ₃ was washed out in pure water and dried. After mixing and kneading by changing the mixing ratio of each powder obtained by the above operation, the pressure is 1000 kg / cm ² , and the diameter is 10 mm and the thickness is 5
mm, and the Li-based mixed powder and the Na-based mixed powder were 1000 ° C. and the Ag-based mixed powder was 7 on a firing setter.
It is fired at 00 ° C. to obtain a conductivity measuring pellet. Apply platinum paste on both sides of each conductivity measurement pellets at 900 ℃
After baking it to provide the counter electrode, 3
The sample was heated to 00 ° C., a complex impedance analysis was performed in the range of 100 Hz to 10 MHz using an impedance meter by the two-terminal method, and the total conductivity (intra-grain + grain-boundary conductivity) was determined. The results are shown in FIGS. Similarly in each case, Li ₄ Sm ₂ Si ₂ O ₉ and Na ₄ Gd ₂ Si with many glass components
An improvement in conductivity is recognized in the composition region where ₂ O ₉ and Ag ₂ SiO ₃ are added in an amount of 10 to 20% by weight. In addition, the more powder with a large glass component is added, the finer the structure with fewer holes from the observation of the fracture surface with an electron microscope, and the vitreous material surrounds the particles of several μm, which is the main component,
Further, it is recognized that the grain boundaries and holes are likely to be filled with glass, and that the decrease in conductivity due to the immersion test in pure water for 24 hours tends to be small. However, on the other hand, while the structure becomes dense as described above, when the powder containing a large amount of glass component is added in an amount of 60% by weight or more, a large decrease of one digit or more is observed in the electric conductivity.

Example 2 To each powder shown in Table 1 obtained by the same operation as in Example 1 was added 20% by weight of a powder containing a large amount of glass component, in which the best improvement in conductivity was observed in FIGS. Table 1 shows the electrical conductivity at 300 ° C. of each pellet obtained by blending the composition.

Also in this example, in the system in which 20% by weight of powder containing a large amount of glass component was added, the conductivity was improved, the structure was densified, and the decrease in conductivity in the immersion test in pure water tended to be small. To be

[0012]

[Table 1]

[0013]

EFFECT OF THE INVENTION Li _1.4 Ti _1.6 In _0.4 P ₃ which is a ceramic electrolyte sintered body having high ionic conductivity.
O ₁₂ , Li ₂ Zr (PO ₄ ) ₂ , Na ₃ Zr ₂ Si ₂ P
O ₁₂ , Na ₂ Zr (PO ₄ ) ₂ , Ag ₃ Zr ₂ Si ₂ P
O ₁₂ and Ag ₂ Zr (PO ₄ ) ₂ etc. were finely pulverized into powders, and Li ₄ Sm ₂ Si ₂ O ₉ , Na ₄ Gd ₂ which is an electrolyte sintered body of the same kind of ion conductor and having many glass components.
Powder of pulverized Si ₂ O ₉ , Ag ₂ SiO _3, etc.
By adding and mixing 0 mass% or less and firing at a relatively low temperature of 900 to 1100 ° C., a solid electrolyte having a high density and a high conductivity was obtained.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a change in conductivity due to addition of an electrolyte containing a large amount of glass components.

FIG. 2 is a diagram for explaining a change in conductivity due to addition of an electrolyte having a large glass component.

FIG. 3 is a diagram illustrating a change in conductivity due to addition of an electrolyte containing a large amount of glass components.

Claims (1)

[Claims] 1. A solid electrolyte made of conductive ceramics, wherein 40% by weight or less of an electrolyte made of an ionic conductor of the same kind as said ceramic electrolyte and having a larger glass component than said ceramics is added to said ceramic electrolyte having high conductivity. A solid electrolyte characterized by being sintered.