JPH0524840A - Synthesis of fluoride in conductor - Google Patents

Abstract

PURPOSE:To synthesize a fluoride ion conductor exhibiting the electric conductivity comparable to that synthesized by a reaction using corrosive gases such as hydrogen fluoride gas or nitrogen trifluoride gas, without using them. CONSTITUTION:A plurality of aqueous solutions comprising an aqueous solution containing a tin salt, an aqueous solution containing a lead salt and an aqueous solution containing a zirconium salt as starting materials are mixed with each other to synthesize the precipitates of a fluoride ion conductor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte used for a solid electrochemical element such as a battery, a sensor including an ion sensor, an electrochemical display element, and the like. The present invention relates to a method for synthesizing an ion conductor that is an ion.

[0002]

2. Description of the Related Art As a fluoride ion conductor, β-P
In addition to bF ₂ , CaF ₂ and LaF ₃ are known, and their electrical conductivity (ionic conductivity) is 10 ⁻⁶ at room temperature.
Many have extremely low S / cm, and recently Pb
It was found by Reau et al. In 1978 that SnF ₄ exhibits a high ionic conductivity of 10 ⁻³ S / cm.

Further, in order to improve the ionic conductivity of the above-mentioned fluoride ion conductor, the present inventors have proposed a fluoride ion conductor obtained by adding zirconium to conventional lead, tin and fluorine. ing.

The above-mentioned fluoride ion conductor (Pb _1-x Sn _1-y Zr _{x + y} F _{4 + 2x + 2y} ) proposed by the present inventors has been developed in a hydrogen fluoride atmosphere as follows. It is synthesized by solid phase reaction.

As a starting material, lead fluoride (Pb
F ₂ ), tin fluoride (SnF ₂ ), zirconium fluoride (Z
rF ₄ ) is mixed with each other and then pressure-molded into pellets. This pellet was put into a nickel reaction tube, the inside of the tube was replaced with argon gas, and then hydrogen fluoride was added to 20 times.
20 ml of argon as carrier gas for ml / min
The reaction tube is heated to 350 ° C. and reacted for 6 hours.

[0006]

The conventionally known fluoride ion conductor PbSnF ₄ or the fluoride ion conductor Pb _1-x Sn _1-y Zr proposed by the present inventors.
The solid phase reaction of _{x + y} F _{4 + 2x + 2y} (0 <x + y ≦ 0.16) must be performed in a hydrogen fluoride atmosphere or a nitrogen trifluoride atmosphere. Since corrosive gas such as hydrogen gas or nitrogen trifluoride gas is used, there is a risk of leakage.

The present invention solves the above problems and makes it possible to use Pb _1-x Sn _1-y Zr _{x + y} F _{4 + 2x} without using a corrosive gas such as hydrogen fluoride gas or nitrogen trifluoride gas. _{+ 2y}
It is an object of the present invention to provide a method for synthesizing a fluoride ion conductor represented by.

[0008]

According to the present invention, an aqueous solution containing a tin salt, an aqueous solution containing a lead salt and an aqueous solution containing a zirconium salt are used as starting materials, and a plurality of aqueous solutions containing the aqueous solution are mixed to obtain fluoride ions. Synthesize a conductor.

In this case, tin fluoride is used as the tin salt, lead nitrate or lead acetate is used as the lead salt, or a mixture thereof, and zirconium fluoride or zirconium oxychloride is used as the zirconium salt. is there.

A plurality of aqueous solutions containing hydrofluoric acid are used as the plurality of aqueous solutions, and after the aqueous solutions are mixed,
The precipitate is heat-treated under an inert gas atmosphere, or the precipitate is pressure-treated after mixing with an aqueous solution.

[0011]

By using an aqueous solution containing a tin salt, an aqueous solution containing a lead salt and an aqueous solution containing a zirconium salt as starting materials, a plurality of aqueous solutions containing the above aqueous solution are mixed to obtain Pb _1-x Sn _1-y Z
Since the fluoride ion conductor represented by r _{x + y} F _{4 + 2x + 2y} can be obtained as a precipitate, without using a corrosive gas such as hydrogen fluoride gas or nitrogen trifluoride gas, Fluoride ion conductors can be synthesized.

The tin salt is preferably used because tin fluoride is a water-soluble fluoride.

As the zirconium salt, zirconium fluoride which is a water-soluble fluoride is preferably used.

As the zirconium salt, zirconium oxychloride is also preferably used because it has water solubility and reacts with hydrogen fluoride to form a fluoride.

As the lead salt, lead nitrate, lead acetate, or a mixture thereof is preferably used because it has water solubility and reacts with hydrofluoric acid to cause precipitation of lead fluoride.

As the plurality of aqueous solutions, an aqueous solution containing hydrofluoric acid is preferably used because it promotes the precipitation of lead fluoride.

Further, the fluoride ion conductor synthesized from the aqueous solution as described above has poor crystallinity as compared with the one thermally synthesized by the solid phase reaction, and as a result, the ion conductivity is low, but It is preferable to perform the heat treatment because the crystallinity and the ionic conductivity are improved by the heat treatment in the active gas atmosphere.

Further, the fluoride ion conductor synthesized from the aqueous solution as described above has its crystallinity and ionic conductivity improved by pressure treatment, and therefore it is preferable to subject the precipitate to pressure treatment. .

[0019]

EXAMPLES The present invention will be described in detail below with reference to examples.

Example 1 As a starting material, tin fluoride (SnF ₂ ), lead nitrate (Pb (NO ₃ ) ₂ ), zirconium oxychloride (ZrOCl ₂ .8H ₂ O) was used, and Pb was prepared by the following method. _1-x Sn _{1 -y} Zr _{x + y} F _{4 + 2x + 2y} (0 <x + y ≦
Pb among the fluoride ion conductors represented by 0.16)
A fluoride ion conductor represented by _0.98 Sn _0.98 Zr _0.04 F _4.08 was obtained.

First, tin fluoride is dissolved in pure water to form a tin fluoride aqueous solution, and hydrofluoric acid (HF _aq. ) _Is added to adjust the pH.
= 5. At the same time, a saturated aqueous solution of lead nitrate and zirconium oxychloride was prepared. After mixing the lead nitrate aqueous solution and the zirconium oxychloride aqueous solution, the mixed aqueous solution is dropped into the tin fluoride aqueous solution so that the molar ratio of lead ion, tin ion and zirconium ion is 0.98: 0.98: 0.04. By doing so, a white precipitate was obtained.

The precipitate was washed with cold water and washed with Pb _0.98 Sn
A fluoride ion conductor represented by _0.98 Zr _0.04 F _4.08 was obtained.

200 mg of the fluoride ion conductor thus obtained was pressure-molded into a pellet of 10 mmφ, and gold thin films were formed on both sides of the pellet by a sputtering method to obtain an electrode for measuring electric conductivity. 20 ℃ by AC impedance method
The electrical conductivity of this fluoride ion conductor was measured in the temperature range from 1 to 300 ° C.

Next, the fluoride ion conductor pellets were heated in an argon stream at 200 ° C. for 24 hours. After that, the electric conductivity was measured in the same manner.

Further, the obtained white precipitate was dried and crushed under pressure with a stirrer for 5 hours, and its electric conductivity was measured by the same method as described above.

[0026] As a comparative example, to obtain a fluoride ion conductor by a solid phase reaction in a conventional hydrogen fluoride atmosphere represented by _{Pb 0.98 Sn 0. 98 Zr 0.04 F} 4.08.

PbF ₂ , SnF ₂ , ZrF as starting materials
₄ ) was weighed in a molar ratio of 0.98: 0.98: 0.04, mixed in an agate mortar and pressed into pellets. This pellet is put into a reaction tube made of nickel, the inside of the tube is replaced with argon, and then 20 ml of hydrogen fluoride is added.
20 ml / min of argon as carrier gas for min
The reaction tube was heated to 350 ° C. and reacted for 6 hours.

The electric conductivity of the thus-obtained fluoride ion conductor was measured by the same method as above.

FIG. 1 (synthesized by the wet method) shows an Arrhenius plot showing the electric conductivity of these fluoride ion conductors according to the present invention compared with those of Comparative Examples.
The results are shown in FIG. 2 (synthesized by the wet method and then heat-treated in argon) and FIG. 3 (synthesized by the wet method and then pressure-treated by a ladle machine). In addition, in FIG.
1 is the electric conductivity of the one synthesized by the wet method according to the present invention, 2 is the electric conductivity of the one synthesized by the solid phase reaction according to the comparative example, and in FIG. 2, 3 is the heat treatment after the synthesis by the wet method according to the present invention. Electrical conductivity of what was 4
3 is the electrical conductivity of the one synthesized by the solid-state reaction according to the comparative example, 5 in FIG. 3 is the electrical conductivity of the one synthesized by the wet method according to the present invention and then subjected to pressure treatment, and 6 is the solid-state reaction according to the comparative example. It is the electrical conductivity of the synthesized material.

From these results, it is found that the fluoride ion conductor according to the present invention has an electric conductivity which is slightly inferior to that obtained by the conventional solid phase reaction, but shows almost the same electric conductivity. It was Further, it has been found that the material subjected to the heat treatment or the pressure treatment according to the present invention exhibits an electric conductivity almost equal to that obtained by the conventional solid phase reaction.

As described above, according to the present invention, without using a corrosive gas such as hydrogen fluoride gas or nitrogen trifluoride gas, an electric power equivalent to that in the conventional solid-phase reaction using these gases is used. It was possible to synthesize a fluoride ion conductor exhibiting conductivity.

Example 2 The molar ratio of lead ion, tin ion and zirconium ion was 0.99: 0.98: 0.
A fluoride ion conductor represented by Pb _0.99 Sn _0.98 Zr _0.03 F _4.06 was obtained in the same manner as in Example 1 except that the mixture was dropped so that the amount became 03.

The thus-obtained fluoride ion conductor was heat-treated in a nitrogen stream at 230 ° C. for 3 hours.

The fluoride ion conductor thus obtained was hot-pressed at 150 ° C. and 6000 kg / cm.
Pressure treatment was performed at a pressure of ² for 10 minutes.

For comparison, PbF₂, SnF₂, Z
rF_FourThe mixing ratio of 0.99: 0.98: 0.0
In the same solid-phase reaction as in the comparative example in Example 1 except that
Pb _0.99Sn_0.98Zr_0.03F_4.06Fluoride represented by
An ionic conductor was obtained.

When the electric conductivity of these fluoride ion conductors was measured in the same manner as in Example 1, the electric conductivity of the fluoride ion conductor according to the present invention was found to be that synthesized by the conventional solid phase reaction. Although it was slightly inferior to the comparative example, it was found that they showed almost the same electric conductivity. Further, it has been found that the material subjected to the heat treatment or the pressure treatment according to the present invention exhibits an electric conductivity almost equal to that obtained by the conventional solid phase reaction.

As described above, according to the present invention, without using corrosive gas such as hydrogen fluoride gas or nitrogen trifluoride gas, an electric power equivalent to that by the conventional solid-phase reaction using these gases is used. It was possible to synthesize a fluoride ion conductor exhibiting conductivity.

Example 3 The molar ratio of lead ion, tin ion and zirconium ion was 0.98: 0.99: 0.
A fluoride ion conductor represented by Pb _0.98 Sn _0.99 Zr _0.03 F _4.06 was obtained in the same manner as in Example 1 except that the mixture was dropped so that the amount became 03.

The fluoride ion conductor thus obtained was heat-treated in the same manner as in Example 1 in an argon stream.

Further, the fluoride ion conductor thus obtained was subjected to a pressure treatment with a stirrer in the same manner as in Example 1.

For comparison, PbF₂, SnF₂, Z
rF_FourThe mixing ratio of 0.98: 0.99: 0.0
In the same solid-phase reaction as in the comparative example in Example 1 except that
Pb _0.98Sn_0.99Zr_0.03F_4.06Fluoride represented by
An ionic conductor was obtained.

When the electric conductivity of these fluoride ion conductors was measured in the same manner as in Example 1, the electric conductivity of the fluoride ion conductor according to the present invention was found to be that synthesized by the conventional solid phase reaction. Although it was slightly inferior to the comparative example, it was found that they showed almost the same electric conductivity. Further, it has been found that the material subjected to the heat treatment or the pressure treatment according to the present invention exhibits an electric conductivity almost equal to that obtained by the conventional solid phase reaction.

As described above, according to the present invention, without using a corrosive gas such as a hydrogen fluoride gas or a nitrogen trifluoride gas, an electric power equivalent to that obtained by the conventional solid-phase reaction using these gases is used. It was possible to synthesize a fluoride ion conductor exhibiting conductivity.

Example 4 In place of lead nitrate, lead acetate (Pb
Pb _0.98 Sn _0.98 Zr _0.04 was prepared in the same manner as in Example 1 except that (CH ₃ COO) ₂ ) was used and zirconium fluoride (ZrF ₄ ) was used instead of zirconium oxychloride.
A fluoride ion conductor represented by F _4.08 was obtained.

The fluoride ion conductor thus obtained was heat-treated in the same manner as in Example 1 in an argon stream.

Further, the fluoride ion conductor thus obtained was subjected to pressure treatment in the same manner as in Example 1 using a stirrer.

For comparison, a fluoride ion conductor represented by Pb _0.98 Sn _0.98 Zr _0.04 F _4.08 was obtained by the same solid-state reaction as in the comparative example of Example 1.

When the electric conductivity of these fluoride ion conductors was measured in the same manner as in Example 1, the electric conductivity of the fluoride ion conductor according to the present invention was found to be that synthesized by the conventional solid phase reaction. Although it was slightly inferior to the comparative example, it was found that they showed almost the same electric conductivity. Further, it has been found that the material subjected to the heat treatment or the pressure treatment according to the present invention exhibits an electric conductivity almost equal to that obtained by the conventional solid phase reaction.

As described above, according to the present invention, without using a corrosive gas such as a hydrogen fluoride gas or a nitrogen trifluoride gas, an electric power equivalent to that obtained by the conventional solid-phase reaction using these gases is used. It was possible to synthesize a fluoride ion conductor exhibiting conductivity.

(Example 5) Except that zirconium oxychloride was replaced with a hydrogen fluoride solution of zirconium hydride (ZrH ₄ ), and tin fluoride was replaced with an aqueous solution of hydrofluoric acid of tin chloride (SnF ₄ ). , Pb in the same manner as in Example 1.
_A fluoride ion conductor represented by _0.98 Sn _0.98 Zr _0.04 F _4.08 was obtained.

The fluoride ion conductor thus obtained was heat-treated in the same manner as in Example 1 in an argon stream.

Further, the fluoride ion conductor thus obtained was subjected to a pressure treatment by using a stirrer in the same manner as in Example 1.

For comparison, a fluoride ion conductor represented by Pb _0.98 Sn _0.98 Zr _0.04 F _4.08 was obtained by the same solid-state reaction as that of the comparative example in Example 1.

The electric conductivity of these fluoride ion conductors was measured in the same manner as in Example 1. The electric conductivity of the fluoride ion conductor according to the present invention was found to be that synthesized by the conventional solid phase reaction. Although it was slightly inferior to the comparative example, it was found that they showed almost the same electric conductivity. Further, it has been found that the material subjected to the heat treatment or the pressure treatment according to the present invention exhibits an electric conductivity almost equal to that obtained by the conventional solid phase reaction.

As described above, according to the present invention, without using a corrosive gas such as hydrogen fluoride gas or nitrogen trifluoride gas, an electric power equivalent to that obtained by the conventional solid phase reaction using these gases is used. It was possible to synthesize a fluoride ion conductor exhibiting conductivity.

As an example of the present invention, Pb _1-x Sn _1-y
Of the fluoride ion conductors represented by Zr _{x + y} F _{4 + 2x + 2y} (0 <x + y ≦ 0.16), Pb _0.98 Sn _0.98 Zr _{0.04
F 4. 08, Pb 0.99 Sn 0.98} Zr 0.03 F 4.06, Pb 0.98 S
The explanation has been given by taking the fluoride ion conductor represented by n _0.99 Zr _0.03 F _4.06 as an example. However, in general, Pb _1-x S
It is needless to say that similar results can be obtained for the fluoride represented by n _1-y Zr _{x + y} F _{4 + 2x + 2y} (0 <x + y ≦ 0.16). It is not limited to the fluoride ion conductor having the composition given in the examples.

Further, as an example of the present invention, the one using zirconium oxychloride, zirconium fluoride or zirconium hydride as the zirconium salt has been described. It is possible to use other zirconium salts such as zirconium dinitrate dihydrate (ZrO (NO ₃ ) ₂ 2H ₂ O) and zirconium acetate (Zr (CH ₃ COO) ₄ ) as long as they cause precipitation. However, the present invention is not limited to the zirconium salts listed in these examples.

Further, as an example of the present invention, the case where tin fluoride or tin chloride is used as the tin salt has been described, but it is also water-soluble and causes precipitation of the fluoride ion conductor. If there is tin bromide (SnBr ₂ ), tin sulfate (S
It is possible to use other tin salts such as nSO ₄ ) and the present invention is not limited to the tin salts mentioned in these examples.

In addition, as an example of the present invention, the case where lead nitrate and lead acetate are used as the lead salt has been described, but any other lead salt having water solubility and causing precipitation of the fluoride ion conductor is described. For example, lead perchlorate trihydrate (Pb (ClO
_{4) 2} · 3H ₂ O), etc. are possible to use other lead salts, the present invention is not limited to the lead salt listed in these examples.

Further, as the pressurizing treatment of the precipitate, the one using a stirrer and the other using a hot press were explained, but a stamp mill, a planetary ball mill, etc.
Needless to say, the same effect can be obtained by pressing with a hydrostatic press or a roll press, and the present invention is not limited to the pressing methods described in these examples.

[0061]

As described above, the aqueous solution containing tin salt, the aqueous solution containing lead salt and the aqueous solution containing zirconium salt are used as starting materials, and a plurality of aqueous solutions containing the aqueous solution are mixed in the present invention. Pb _1-x Sn _1-y Zr _{x + y} F which shows the same electric conductivity as that of the conventional solid-phase reaction using these gases without using corrosive gases such as nitrogen trifluoride gas. A fluoride ion conductor represented by _{4 + 2x + 2y} could be synthesized.

Further, by using tin fluoride as the tin salt, it was possible to synthesize a fluoride ion conductor having an electric conductivity equivalent to that obtained by the conventional solid phase reaction.

By using lead nitrate, lead acetate, or a mixture thereof as the lead salt, it is possible to synthesize a fluoride ion conductor having an electric conductivity equivalent to that obtained by the conventional solid phase reaction. It was

Further, by using zirconium fluoride or zirconium oxychloride as the zirconium salt, it was possible to synthesize a fluoride ion conductor having an electric conductivity equivalent to that obtained by the conventional solid phase reaction.

Further, by using a plurality of aqueous solutions containing hydrofluoric acid as the plurality of aqueous solutions, it is possible to synthesize a fluoride ion conductor having an electric conductivity equivalent to that obtained by the conventional solid phase reaction. It was

Further, after mixing the aqueous solution, the precipitate is heat-treated or pressure-treated in an inert gas atmosphere to give a fluoride having an electric conductivity equivalent to that of the conventional solid-phase reaction. An ionic conductor could be synthesized.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing the electric conductivity of a fluoride ion conductor according to an embodiment of the present invention together with a comparative example.

FIG. 2 is a characteristic diagram showing the electric conductivity of a fluoride ion conductor according to an embodiment of the present invention together with a comparative example.

FIG. 3 is a characteristic diagram showing the electric conductivity of a fluoride ion conductor according to one embodiment of the present invention together with a comparative example.

[Explanation of symbols]

1 Electric conductivity of the one synthesized by the wet method according to the present invention 2 Electric conductivity of one synthesized by the solid-phase reaction according to the comparative example 3 Electric conductivity of the one synthesized by the wet method according to the present invention followed by heat treatment 4 The solid phase according to the comparative example Electric conductivity of the one synthesized by the reaction 5 Electric conductivity of the one synthesized by the wet method according to the present invention and then subjected to pressure treatment 6 Electric conductivity of the one synthesized by the solid phase reaction according to the comparative example

Claims (8)

[Claims] 1. An aqueous solution containing a tin salt, an aqueous solution containing a lead salt, and an aqueous solution containing a zirconium salt are used as starting materials, and a plurality of aqueous solutions containing the aqueous solution are mixed to obtain at least tin, lead,
A method for synthesizing a fluoride ion conductor, characterized in that a compound containing zirconium is obtained as a precipitate. 2. The method for synthesizing a fluoride ion conductor according to claim 1, wherein the tin salt is tin fluoride or tin chloride. 3. The method for synthesizing a fluoride ion conductor according to claim 1, wherein the lead salt is lead nitrate, lead acetate, or a mixture thereof. 4. The method for synthesizing a fluoride ion conductor according to claim 1, wherein the zirconium salt is zirconium fluoride. 5. The method for synthesizing a fluoride ion conductor according to claim 1, wherein the zirconium salt is zirconium oxychloride or zirconium hydride. 6. The method for synthesizing a fluoride ion conductor according to claim 1, wherein the plurality of aqueous solutions contain hydrofluoric acid. 7. The method for synthesizing a fluoride ion conductor according to claim 1, wherein the precipitate is heated and cooked in an inert gas atmosphere after mixing the aqueous solution. 8. The method for synthesizing a fluoride ion conductor according to claim 1, wherein the precipitate is pressure-treated after mixing the aqueous solution.