KR102656700B1 - Manufacturing method of nasicon crystal structure compound for sodium ion solid electrolyte - Google Patents

Abstract

By adding glass frit, which is used as a sintering aid, to Nasicon powder during the manufacturing process of Nasicon crystal structure compounds, the Nasicon crystal structure is effectively densified despite lowering the temperature of the sintering process and shortening the sintering time. Disclosed is a Nasicon crystal structure compound for sodium ion solid electrolyte that can improve conductivity and density and a method for producing the same.
The method for producing a Nasicon crystal structure compound for a sodium ion solid electrolyte according to the present invention includes the steps of (a) first mixing and pulverizing a sodium precursor, a zirconium precursor, a silicon precursor, and a phosphorus precursor; (b) putting the first mixed and pulverized mixed precursor into a heat treatment furnace and calcining it to form Nasicon powder; (c) adding glass frit to the Nashikon powder, followed by secondary mixing and grinding; (d) putting the Naxicon powder mixed with the glass frit into a mold and pressing it to form a pellet; and (e) putting the Nassicon molded product in the pellet form into a heat treatment furnace and then sintering it to form a Nassicon crystal structure compound.

Description

{MANUFACTURING METHOD OF NASICON CRYSTAL STRUCTURE COMPOUND FOR SODIUM ION SOLID ELECTROLYTE}

The present invention relates to a Narsicon crystal structure compound for sodium ion solid electrolyte and a method for producing the same. More specifically, in the process of manufacturing the Narsicon crystal structure compound, glass frit used as a sintering aid is added to Nassicon powder. , about the Nassicon crystal structure compound for sodium ion solid electrolyte and its manufacturing method, which can improve ionic conductivity and density by effectively densifying the Narsicon crystal structure compound despite reducing the sintering time while lowering the temperature of the sintering process. will be.

Safe and efficient energy storage and use is one of the most important issues in modern society. To this end, research on the development of next-generation secondary batteries has been actively conducted recently. Among these, sodium-based secondary batteries have been receiving a lot of attention since the 2010s due to their easier supply of raw materials compared to lithium.

In particular, recently, new types of sodium-based secondary batteries such as all-solid-state sodium batteries, hybrid sodium-air batteries, and seawater secondary batteries have been proposed based on advanced technologies.

As a key material for implementing such sodium-based secondary batteries, the development of a solid electrolyte with high sodium ion conductivity and excellent physical and chemical stability is essential.

In general, compounds with a crystal structure of NASICON (Na superionic conductor) have a sodium ion conductivity of more than 10 ^-4 S/cm and a wide electrochemical window, making them suitable for use in sodium-based secondary batteries. It has characteristics.

In addition, compounds with a Nasicon crystal structure are chemically stable not only in air but also in seawater, and are used as a core material for ceramic separators for seawater secondary batteries.

However, in the case of compounds with a crystal structure of Nassicon, it is necessary to densify Nassicon through a high temperature sintering process of about 1,200°C or higher in order to derive the inherent high ionic conductivity characteristics.

This high-temperature sintering process promotes the volatilization of sodium (Na) and phosphorus (P) components, causing the problem that it is difficult to obtain a compound with a Nasicon crystal structure of the desired composition after the sintering process.

Related prior literature includes Korean Patent Publication No. 10-2014-0056898 (published on May 12, 2014), which describes a sodium battery and its manufacturing method.

The object of the present invention is to lower the temperature of the sintering process and shorten the sintering time by adding glass frit, which is used as a sintering aid, to Naxicon powder in the manufacturing process of a Naxicon crystal structure compound. The object of the present invention is to provide a Nasicon crystal structure compound for sodium ion solid electrolyte that can effectively densify the compound to improve ionic conductivity and density, and a method for producing the same.

To achieve the above object, a method for producing a Naxicon crystal structure compound for a sodium ion solid electrolyte according to an embodiment of the present invention includes the steps of (a) first mixing and pulverizing a sodium precursor, a zirconium precursor, a silicon precursor, and a phosphorus precursor; (b) putting the first mixed and pulverized mixed precursor into a heat treatment furnace and calcining it to form Nasicon powder; (c) adding glass frit to the Nashikon powder, followed by secondary mixing and grinding; (d) putting the Naxicon powder mixed with the glass frit into a mold and pressing it to form a pellet; and (e) putting the Nassicon molded product in the pellet form into a heat treatment furnace and then sintering it to form a Nassicon crystal structure compound.

In step (a), the sodium precursor preferably includes one or more selected from Na ₃ PO ₄ and Na ₂ CO ₃ , and the zirconium precursor is ZrO ₂ .

In step (a), it is preferable that the silicon precursor is SiO ₂ and the phosphorus precursor is Na ₃ PO ₄ .

In step (b), the calcination is performed at a temperature of 800 to 1,200°C for 1 to 24 hours.

In step (c), 90 to 99.5% by weight of the Nasicon powder; And the glass frit is added in an amount of 0.5 to 10% by weight.

In step (c), the Nacicon powder is added in an amount of 94 to 98% by weight and the glass frit is added in an amount of 2 to 6% by weight.

In step (e), the sintering is performed at a low temperature of 1,000 to 1,200°C for 0.5 to 5 hours.

In step (e), the sintering is performed at 1,100 to 1,200°C for 0.5 to 2 hours.

In step (e), the Nasicon crystal structure compound is Na _1+x Zr ₂ Si _x P _3-x O ₁₂ (0 ≤ x ≤ 3) or Na _0.8+x Zr _1.55 Si _x P _3-x O ₁₁ It has a composition of (2.0 < x < 2.5).

After step (e), the Nasicon crystal structure compound has an ionic conductivity of 5.0 × 10 ^-4 S/cm or more.

After step (e), the Nasicone crystal structure compound has a density of 2.5 g/cm3 or more.

The Narsicon crystal structure compound for sodium ion solid electrolyte according to an embodiment of the present invention to achieve the above object is a sodium ion solid electrolyte obtained by adding glass frit to Nassicon powder and sintering at low temperature at 1,000 to 1,200°C for 0.5 to 5 hours. As a Nasicon crystal structure compound, the Nasicon crystal structure compound is 90 to 99.5% by weight of the Nasicon powder; And 0.5 to 10% by weight of the glass frit.

The Narsicon crystal structure compound is 90 to 99.5% by weight of the Nassicon powder; And the glass frit is added in an amount of 0.5 to 10% by weight.

The Nasicon crystal structure compound is Na _1+x Zr ₂ Si _x P _3-x O ₁₂ (0 ≤ x ≤ 3) or Na _0.8+x Zr _1.55 Si _x P _3-x O ₁₁ (2.0 < x < 2.5) It has the composition of

The Nasicon crystal structure compound has an ionic conductivity of 5.0 × 10 ^-4 S/cm or more.

The Nasicon crystal structure compound has a density of 2.5 g/cm3 or more.

The Nasicon crystal structure compound for sodium ion solid electrolyte according to the present invention and the manufacturing method thereof include adding a glass frit to Nasicon powder and performing low-temperature sintering at a lower temperature and for a shorter time, thereby producing sodium (Na) and phosphorus (P). ) It is possible to densify the Nassicon crystal structure compound without worrying about volatilization of the components, thereby securing the Nassicon crystal structure of the desired composition after the sintering process.

Therefore, the Nasicon crystal structure compound for sodium ion solid electrolyte and the manufacturing method thereof according to the present invention lower the temperature of the sintering process and shorten the sintering time by adding glass frit, which is used as a sintering aid, to Nasicon powder. Despite Na _1+x Zr ₂ Si _x P _3-x O ₁₂ (0 ≤ x ≤ 3) or Na _0.8+x Zr _1.55 Si _x P _3-x O ₁₁ (2.0 < x < 2.5) By effectively densifying the cone crystal structure compound, ionic conductivity and density can be improved.

As a result, the Nasicon crystal structure compound for sodium ion solid electrolyte according to the present invention and its manufacturing method are capable of securing an ionic conductivity of 5.0 × 10 ^-4 S/cm or more and a density of 2.5 g/cm3 or more, making it possible to secure a sodium-based secondary It is suitable for use in batteries and is chemically stable not only in air but also in seawater, so it can be used as a core material for ceramic separators for seawater secondary batteries.

Figure 1 is a process flow chart showing a method for producing a Nacicon crystal structure compound for a sodium ion solid electrolyte according to an embodiment of the present invention.
Figure 2 is a measured photograph showing a sample prepared according to Example 2.
Figure 3 is a graph showing the results of X-ray diffraction measurement for samples prepared according to Examples 1 to 4 and Comparative Example 1.
Figure 4 is a graph showing the results of impedance analysis for samples prepared according to Examples 1 to 4 and Comparative Example 1.
Figure 5 is an SEM photograph showing the surface of a sample prepared according to Comparative Example 1.
Figure 6 is an SEM photograph showing the surface of the sample prepared according to Example 2.
Figure 7 is an SEM photograph showing the surface of the sample prepared according to Example 4.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms. The present embodiments only serve to ensure that the disclosure of the present invention is complete and that common knowledge in the technical field to which the present invention pertains is provided. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, with reference to the attached drawings, a detailed description will be given of the Nasicon crystal structure compound for sodium ion solid electrolyte and the method of manufacturing the same according to a preferred embodiment of the present invention.

The Nassicon crystal structure compound for sodium ion solid electrolyte according to an embodiment of the present invention is formed by adding a glass frit to Nassicon powder and sintering it at a low temperature at 1,000 to 1,200°C for 0.5 to 5 hours.

In the present invention, through experiments, a Nasicon crystal structure compound prepared by adding glass frit as a sintering aid and then performing low-temperature sintering at 1,200°C for 1 hour was found to be sintered under the same sintering conditions (1,200°C, 1 hour). It was confirmed that it exhibits higher ionic conductivity and density than the Nasicon crystal structure compound prepared without adding. In addition, it was confirmed that under high temperature sintering conditions (1,250°C, 12 hours), the ion conductivity and density were similar to those of the Nasicon crystal structure compound manufactured without adding glass frit.

To this end, it is preferable that the Nasicon crystal structure compound for sodium ion solid electrolyte according to an embodiment of the present invention includes 90 to 99.5% by weight of Nasicon powder and 0.5 to 10% by weight of glass frit.

Here, the glass frit melts at a temperature below 1,200°C and induces liquid phase sintering of the Nassicon crystals, enabling densification of the Nassicon crystals at a relatively low temperature.

It is preferable to use sodium borosilicate-based powder as the glass frit. More specifically, it is more preferable to use a glass frit to which CaO and Al ₂ O ₃ components are added to a sodium borosilicate system. As an example, the glass frit may be composed of Na ₂ O 1 to 15 wt%, CaO 1 to 30 wt%, B ₂ O ₃ 5 to 30 wt%, Al ₂ O ₃ 1 to 25 wt%, and the remaining amount of SiO _2. However, it is not limited to this.

This glass frit is preferably added in an amount of 0.5 to 10% by weight of the total weight of the Nasicon crystal structure compound, and a more preferable range is 2 to 6% by weight.

If the amount of glass frit added is too small, less than 0.5% by weight of the total weight of the Nassicon crystal structure compound, there is a high risk that densification of the Nassicon crystal structure compound through liquid phase sintering will not proceed smoothly. On the other hand, if the amount of glass frit added is too much, exceeding 10% by weight of the total weight of the Nassicon crystal structure compound, an excessive secondary phase is formed and large pores are formed in parts, thereby increasing the ions of the Nassicon crystal structure compound. This reduces conductivity and density.

The Narsicon crystal structure compound for sodium ion solid electrolyte according to the above-described embodiment of the present invention is obtained by adding glass frit to Nassicon powder and performing low-temperature sintering at a lower temperature and for a shorter time, producing sodium (Na) and It is possible to densify the Nassicon crystal structure compound without worrying about volatilization of the phosphorus (P) component, thereby securing the Nassicon crystal structure of the desired composition after the sintering process.

Therefore, the Nasicon crystal structure compound for sodium ion solid electrolyte according to an embodiment of the present invention lowers the temperature of the sintering process and shortens the sintering time by adding glass frit, which is used as a sintering auxiliary, to Nasicon powder. Despite Na _1+x Zr ₂ Si _x P _3-x O ₁₂ (0 ≤ x ≤ 3) or Na _0.8+x Zr _1.55 Si _x P _3-x O ₁₁ (2.0 < x < 2.5) By effectively densifying the crystal structure compound, ionic conductivity and density can be improved.

As a result, the Nasicon crystal structure compound for sodium ion solid electrolyte according to an embodiment of the present invention has an ionic conductivity of 5.0 × 10 ^-4 S/cm or more and a density of 2.5 g/cm3 or more, more preferably 5.0 × 10 ^-4 ~ It is possible to secure an ionic conductivity of ^3.0 It can be used as a core material for ceramic separators for secondary batteries.

Hereinafter, with reference to the attached drawings, a method for manufacturing a Nasicon structure composite oxide for a sodium ion solid electrolyte according to an embodiment of the present invention will be described.

Figure 1 is a process flowchart showing a method for producing a Nasicon crystal structure compound for a sodium ion solid electrolyte according to an embodiment of the present invention.

As shown in Figure 1, the method for producing a Nasicon crystal structure compound for sodium ion solid electrolyte according to an embodiment of the present invention includes a first mixing and grinding step (S110), a calcination step (S120), and a second mixing and grinding step. (S130), pressure forming step (S140), and sintering step (S150).

Primary mixing and grinding

In the first mixing and pulverizing step (S110), the sodium precursor, zirconium precursor, silicon precursor, and phosphorus precursor are first mixed and pulverized.

The sodium precursor preferably includes one or more selected from Na ₃ PO ₄ and Na ₂ CO ₃ , and the zirconium precursor is ZrO ₂ .

Additionally, it is preferable that the silicon precursor is SiO ₂ and the phosphorus precursor is Na ₃ PO ₄ .

In this step, the sodium precursor, zirconium precursor, silicon precursor, and phosphorus precursor are described as using phosphate, oxide, or carbonate-based precursors, but are not limited to these, and are not limited to nitrate, acetate ( Acetate, hydroxide, hydrate, chloride precursors, etc. may be used.

calcination

In the calcination step (S120), the first mixed and pulverized mixed precursor is put into a heat treatment furnace and then calcinated to form Nacicon powder.

In this step, calcination is preferably performed at a temperature of 800 to 1,200°C for 1 to 24 hours. If the calcination temperature is less than 800°C or the calcination time is less than 1 hour, there is a risk that the reaction between the mixed precursors may not occur properly. Conversely, when the calcination temperature exceeds 1,200°C or the calcination time exceeds 24 hours, mixed precursors may react with each other to form locally different compositions, and there is a problem in that the size of the crystal grains becomes excessively large.

Secondary mixing and grinding

In the secondary mixing and grinding step (S130), glass frit is added to Nasicon powder and then secondary mixing and grinding are performed.

In this secondary mixing and grinding step, it is preferable to add 90 to 99.5% by weight of Nasicon powder and 0.5 to 10% by weight of glass frit.

Here, the glass frit melts at a temperature below 1,200°C and induces liquid phase sintering of the Nassicon crystals, enabling densification of the Nassicon crystals at a relatively low temperature.

It is preferable to use sodium borosilicate-based powder as the glass frit. More specifically, it is more preferable to use a glass frit to which CaO and Al ₂ O ₃ components are added to a sodium borosilicate system. As an example, the glass frit may be composed of Na ₂ O 1 to 15 wt%, CaO 1 to 30 wt%, B ₂ O ₃ 5 to 30 wt%, Al ₂ O ₃ 1 to 25 wt%, and the remaining amount of SiO _2. However, it is not limited to this.

This glass frit is preferably added in an amount of 0.5 to 10% by weight, and a more preferable range is 2 to 6% by weight.

If the amount of glass frit added is too small (less than 0.5% by weight), there is a high risk that densification of the Nasicon crystal structure compound by liquid phase sintering will not proceed smoothly. On the other hand, if the amount of glass frit added is too large, exceeding 10% by weight, excessive secondary phase is formed during the sintering process and large pores are partially formed, which reduces the ionic conductivity and density of the Nassicon crystal structure compound. It will be done.

pressure molding

In the pressure molding step (S140), Nasicon powder mixed with glass frit is put into a mold, and pressurized to form a pellet.

Here, a manual hydraulic press may be used to pressurize to form a pellet, but is not limited thereto.

sintering

In the sintering step (S150), the Nassicon molded product in the form of a pellet is put into a heat treatment furnace and then sintered to form a Nassicon crystal structure compound.

In this step, sintering is preferably performed at a low temperature of 1,000 to 1,200°C for 0.5 to 5 hours. More preferably, sintering is performed at 1,100 to 1,200°C for 0.5 to 2 hours.

As such, in the present invention, low-temperature sintering was performed at a lower temperature and with shorter time by adding a glass frit to Nasicon powder. Accordingly, it is possible to densify the Nassicon crystal structure compound without worrying about volatilization of sodium (Na) and phosphorus (P) components, thereby securing the Nassicon crystal structure of the desired composition after the sintering process.

In addition, in the present invention, low-temperature sintering is performed at a low temperature of 1,200°C or less in 5 hours or less, and process costs and time can be reduced by reducing the sintering temperature and shortening the sintering time.

At this time, if the sintering temperature is less than 1,000°C or the sintering time is less than 0.5 hours, there is a high risk that ionic conductivity and density will be lowered because crystallization may not occur properly. Conversely, if the sintering temperature exceeds 1,200°C or the sintering time exceeds 5 hours, it may act as a factor that only increases process cost and time without improving ionic conductivity and density.

It was confirmed through experiments that the Nassicon crystal structure compound exhibits high ionic conductivity and density only after completing this sintering step (S150).

Therefore, after the sintering step (S150), the Nasicon crystal structure compound is Na _1+x Zr ₂ Si _x P _3-x O ₁₂ (0 ≤ x ≤ 3) or Na _0.8+x Zr _1.55 Si _x P _3-x O It has a composition of ₁₁ (2.0 < x < 2.5) and exhibits an ionic conductivity of more than ^5.0

With this, the method for producing a Nasicon crystal structure compound for sodium ion solid electrolyte according to an embodiment of the present invention can be completed.

As seen so far, the method for producing a Nacicon crystal structure compound for a sodium ion solid electrolyte according to an embodiment of the present invention is to add glass frit to Naxicon powder and perform low-temperature sintering at a lower temperature and for a shorter time, thereby producing sodium. It is possible to densify the Nassicon crystal structure compound without fear of volatilization of (Na) and phosphorus (P) components, thereby securing the Nassicon crystal structure of the desired composition after the sintering process.

Therefore, the method for producing a Nasicon crystal structure compound for a sodium ion solid electrolyte according to an embodiment of the present invention reduces the sintering time while lowering the temperature of the sintering process by adding glass frit, which is used as a sintering aid, to Nasicon powder. Despite having a composition of Na _1+x Zr ₂ Si _x P _3-x O ₁₂ (0 ≤ x ≤ 3) or Na _0.8+x Zr _1.55 Si _x P _3-x O ₁₁ (2.0 < x < 2.5) By effectively densifying the Nasicon crystal structure compound, ionic conductivity and density can be improved.

As a result, the Nacicon crystal structure compound for sodium ion solid electrolyte prepared by the method according to the embodiment of the present invention is capable of securing an ionic conductivity of 5.0 × 10 ^-4 S/cm or more and a density of 2.5 g/cm3 or more, thereby enabling sodium It is suitable for use in secondary batteries and is chemically stable not only in air but also in seawater, so it can be used as a core material for ceramic separators for seawater secondary batteries.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and should not be construed as limiting the present invention in any way.

Any information not described here can be technically inferred by anyone skilled in the art, so description thereof will be omitted.

1. Nasicon crystal structure compound sample preparation

Example 1

Na ₃ PO ₄ , Na ₂ CO ₃ , ZrO ₂ and SiO ₂ were weighed and then first mixed and pulverized using planetary mill equipment.

Next, the first mixed and pulverized mixed precursor was put into a heat treatment furnace and then calcined at 1,100°C for 12 hours to form Nacicon powder.

Next, glass frit was added to Nasicon powder, and then secondary mixing and pulverization were performed using planetary mill equipment. At this time, 98 wt% of Nasicon powder and 2 wt% of glass frit were added.

Next, Nasicon powder mixed with glass frit was put into a mold and pressed with a manual hydraulic press to form a pellet.

Next, the Nassicon molded product in the form of a pellet was put into a heat treatment furnace and sintered at 1,200°C for 1 hour to produce a Nassicon crystal structure compound with a composition of Na _3.1 Zr _1.55 Si _2.3 P _0.7 O ₁₁ (x = 2.3). was manufactured.

Example 2

When adding glass frit to Nassicon powder, a Nassicon crystal structure compound was prepared in the same manner as in Example 1, except that it was added in an amount ratio of 96 wt% for Nassicon powder and 4 wt% for glass frit.

Example 3

When adding glass frit to Nassicon powder, a Nassicon crystal structure compound was prepared in the same manner as in Example 1, except that it was added at a content ratio of 94 wt% for Nassicon powder and 6 wt% for glass frit.

Example 4

When adding glass frit to Nassicon powder, a Nassicon crystal structure compound was prepared in the same manner as in Example 1, except that it was added in an amount ratio of 92 wt% for Nassicon powder and 8 wt% for glass frit.

Comparative Example 1

After weighing Na ₃ PO ₄ , Na ₂ CO ₃ , ZrO ₂ and SiO ₂ , they were initially mixed and pulverized using planetary mill equipment.

Next, the first mixed and pulverized mixed precursor was put into a heat treatment furnace and then calcined at 1,100°C for 12 hours to form Nacicon powder.

Next, the Nasicon powder was put into a mold without adding glass frit to the Nasicon powder, and pressed with a manual hydraulic press to form a pellet.

Next, the Nassicon molded product in the form of a pellet was put into a heat treatment furnace and sintered at 1,200°C for 1 hour to produce a Nassicon crystal structure compound with a composition of Na _3.1 Zr _1.55 Si _2.3 P _0.7 O ₁₁ (x = 2.3). was manufactured.

Comparative Example 2

A Nasicone crystal structure compound was prepared in the same manner as Comparative Example 1, except that it was sintered at 1,250°C for 12 hours.

2. X-ray diffraction pattern analysis

Figure 2 is a measured photograph showing a sample prepared according to Example 2.

As shown in Figure 2, the Nasicone crystal structure compound prepared according to Example 2 is shown. At this time, the Nasicon crystal structure compound manufactured according to Example 2 can be seen to have a smooth surface without defects such as cracks in the final photo of the pellet form after the sintering process has been completed.

Figure 3 is a graph showing the results of X-ray diffraction measurement for samples prepared according to Examples 1 to 4 and Comparative Example 1.

As shown in FIG. 3, in the sample prepared according to Comparative Example 1, only a pure Nassicon crystal phase was observed due to the fact that no glass frit was added.

In addition, it can be confirmed that in the samples prepared according to Examples 1 to 4 in which glass frit was added at an amount of 2 to 8 wt%, only a pure Naxicon crystal phase was observed, the same as the sample prepared according to Comparative Example 1.

As can be seen based on the above experimental results, it was confirmed that the Nacicon crystal phase was formed without any problems even when glass frit was added.

3. Physical property evaluation

Table 1 shows the physical property evaluation results for the samples prepared according to Examples 1 to 4 and Comparative Examples 1 to 2, and Figure 4 shows the impedance analysis of the samples prepared according to Examples 1 to 4 and Comparative Example 1. This is a graph showing the results.

[Table 1]

As shown in Table 1 and Figure 4, the impedance analysis results for the Nacicon crystal structure compound prepared according to Examples 1 to 4 and Comparative Example 1 until the sintering process was completed are shown. Using these impedance analysis results, the ionic conductivity of the Nasicone crystal structure compound was calculated.

The Narsicon crystal structure compounds according to Examples 1 to 4 prepared by adding glass frit at an content ratio of 2 to 8 wt% have ionic conductivity compared to the Nassicon crystal structure compounds according to Comparative Example 1 prepared without adding glass frit. It was confirmed that the density was greatly improved.

Here, the Nassicon crystal structure compound according to Example 4, prepared by adding glass frit at an content ratio of 8 wt%, has higher ionic conductivity and density than the Nassicon crystal structure compound according to Comparative Example 1 prepared without adding glass frit. It was measured.

However, the Nassicon crystal structure compound according to Example 4 prepared by adding glass frit at an content ratio of 8 wt% is the Nassicon crystal structure compound according to Example 4 prepared by adding glass frit at an optimal content ratio of 4 wt%. It was confirmed that the ionic conductivity and density were relatively reduced compared to the compound. Therefore, it is judged that the optimal content ratio of glass frit is 2 to 6 wt%.

In addition, in the case of the Nasicon crystal structure compound according to Example 2, which was manufactured by adding glass frit at an optimal content ratio of 4 wt%, it was sintered under existing sintering process conditions (1,250°C, 12 hours) without adding glass frit. Even though the sintering temperature was lowered and the sintering time was shortened (1,200°C, 1 hour) compared to the Nasicon crystal structure compound prepared according to Comparative Example 2, it was confirmed that the ionic conductivity and density were superior.

4. Microstructure observation

Figure 5 is an SEM photograph showing the surface of the sample prepared according to Comparative Example 1. Figure 6 is an SEM photograph showing the surface of a sample prepared according to Example 2, and Figure 7 is an SEM photograph showing the surface of a sample prepared according to Example 4.

As shown in FIG. 5, like the sample prepared according to Comparative Example 1, when no glass frit was added, densification did not proceed smoothly, and it can be confirmed that a large number of pores exist on the surface.

On the other hand, as shown in FIG. 6, it can be seen that the surface porosity of the Nasicon crystal structure compound prepared by adding glass frit at a content ratio of 4 wt%, like the sample prepared according to Example 2, was significantly reduced. .

In addition, as shown in Figure 7, like the sample prepared according to Example 4, the Nassicon crystal structure compound prepared by adding glass frit at an content ratio of 8 wt% is similar to the Nassicon crystal manufactured without adding glass frit. Although densification proceeded relatively more smoothly than the structural compound, it was confirmed that large pores were observed locally.

Although the above description focuses on the embodiments of the present invention, various changes or modifications can be made at the level of a person skilled in the art in the technical field to which the present invention pertains. These changes and modifications can be said to belong to the present invention as long as they do not depart from the scope of the technical idea provided by the present invention. Therefore, the scope of rights of the present invention should be determined by the claims described below.

S110: First mixing and grinding step
S120: Calcination step
S130: Second mixing and grinding step
S140: Pressure forming step
S150: Sintering step

Claims (16)

(a) primary mixing and pulverizing a sodium precursor, a zirconium precursor, a silicon precursor, and a phosphorus precursor;
(b) putting the first mixed and pulverized mixed precursor into a heat treatment furnace and calcining it to form Nasicon powder;
(c) adding glass frit to the Nashikon powder, followed by secondary mixing and grinding;
(d) putting the Naxicon powder mixed with the glass frit into a mold and pressing it to form a pellet; and
(e) putting the Nassicon molded product in the pellet form into a heat treatment furnace and sintering it to form a Nassicon crystal structure compound;
In step (c), 90 to 99.5% by weight of the Nasicon powder; And the glass frit is added in an amount of 0.5 to 10% by weight,
The glass frit is used as a composition of Na ₂ O 1 to 15 wt%, CaO 1 to 30 wt%, B ₂ O ₃ 5 to 30 wt%, Al ₂ O ₃ 1 to 25 wt%, and the remaining amount of SiO ₂ ,
In step (e), the Nasicon crystal structure compound is Na _1+x Zr ₂ Si _x P _3-x O ₁₂ (0 ≤ x ≤ 3) or Na _0.8+x Zr _1.55 Si _x P _3-x O ₁₁ It has the composition of (2.0 < x < 2.5),
After step (e), the Naxicon crystal structure compound is a sodium ion solid electrolyte characterized in that it has an ionic conductivity of 5.0 × 10 ^-4 to 3.0 × 10 ^-3 S/cm and a density of 2.5 to 3.3 g/cm3. Nasicon crystal structure compound manufacturing method.
According to paragraph 1,
In step (a) above,
The sodium precursor includes one or more selected from Na ₃ PO ₄ and Na ₂ CO ₃ ,
The zirconium precursor is ZrO _2. A method for producing a Nasicon crystal structure compound for a sodium ion solid electrolyte.
According to paragraph 1,
In step (a) above,
The silicon precursor is SiO ₂ ,
The phosphorus precursor is Na ₃ PO _4. A method for producing a Nasicone crystal structure compound for a sodium ion solid electrolyte.
According to paragraph 1,
In step (b) above,
The above calcination
A method for producing a Nasicon crystal structure compound for a sodium ion solid electrolyte, characterized in that it is carried out at a temperature of 800 to 1,200°C for 1 to 24 hours.
delete According to paragraph 1,
In step (c) above,
A method for producing a Nasicon crystal structure compound for a sodium ion solid electrolyte, characterized in that the Nasicon powder is added in a content ratio of 94 to 98% by weight and the glass frit is 2 to 6% by weight.
According to paragraph 1,
In step (e) above,
The sintering is
A method for producing a Nasicon crystal structure compound for a sodium ion solid electrolyte, characterized in that it is carried out at a low temperature of 1,000 to 1,200°C for 0.5 to 5 hours.
In clause 7,
In step (e) above,
The sintering is
A method for producing a Nasicon crystal structure compound for sodium ion solid electrolyte, characterized in that it is carried out at 1,100 ~ 1,200 ℃ for 0.5 ~ 2 hours.
delete delete delete delete delete delete delete delete

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