KR102159572B1 - Method for manufacturing solid electrolyte - Google Patents

Abstract

The present invention relates to a method for producing a solid electrolyte in which a polymer material is filled in pores. A method of preparing a solid electrolyte according to an embodiment of the present invention includes the steps of: (A) impregnating a solid electrolyte in a solution in which a monomer is dissolved; And (B) heating the solid electrolyte filled with the monomers in the pores.

Description

Method for producing solid electrolyte {METHOD FOR MANUFACTURING SOLID ELECTROLYTE}

The present invention relates to a method of manufacturing a solid electrolyte, and more particularly, to a method of manufacturing a solid electrolyte in which a polymer material is filled in pores.

In a secondary battery, metal ions (eg, lithium ions, sodium ions) move from the positive electrode to the negative electrode during charging, and during discharge, the metal ions move from the negative electrode to the positive electrode. In this case, the solid electrolyte between the anode portion and the cathode portion must facilitate the transfer of metal ions and maintain an electrically insulating state. Accordingly, a secondary battery includes various materials and designs, and a secondary battery requiring high induction current efficiency uses a solid electrolyte separator.

However, ceramic solid electrolytes have a disadvantage in that they are easily broken due to their thick and weak strength, and their density is low, so that liquids or gases such as water (H ₂ O) can permeate through the pores. Therefore, there is a need to prepare a solid electrolyte in which these disadvantages are solved, but the research results on this are still insufficient.

[Patent Document 1] Korean Patent Application Publication No. 10-2018-0070093

The present invention has been created to solve the above-described problem, and an object of the present invention is to provide a method for producing a solid electrolyte filled with a polymer material in pores.

The objects of the present invention are not limited to the objects mentioned above, and other objects not mentioned will be clearly understood from the following description.

In order to achieve the above objects, a method of preparing a solid electrolyte according to an embodiment of the present invention includes the steps of: (A) impregnating a solid electrolyte in a solution in which a monomer is dissolved; And (B) heating the solid electrolyte filled with the monomers in the pores.

In an embodiment, the method of preparing the solid electrolyte may further include, between steps (A) and (B), (C) placing the solid electrolyte impregnated in the solution in a vacuum chamber.

In an embodiment, the method of preparing the solid electrolyte further includes, after the step (B), (C) polishing a polymer generated on the surface of the solid electrolyte; wherein the polymer further comprises, the ( It can be produced from the monomer through step B).

In an embodiment, the step (A) may include casting a solution in which the monomer is dissolved in a solid electrolyte.

In an embodiment, the method of preparing the solid electrolyte may further include dissolving the monomer in a solvent before step (A).

In an embodiment, the method of preparing the solid electrolyte includes the steps of (C) adding a precursor to a solvent to form a slurry before step (A); (D) drying the slurry to produce granules; (E) compressing the granules to produce a solid compact; And (F) generating the solid electrolyte by sintering the solid compact.

In an embodiment, a method of manufacturing a secondary battery includes a method of manufacturing the solid electrolyte; Forming a positive electrode portion including a positive electrode current collector impregnated with a sodium-containing solution; And forming a negative electrode part including a negative electrode current collector impregnated with the organic electrolyte.

Specific matters for achieving the above objects will become apparent with reference to embodiments to be described later in detail together with the accompanying drawings.

However, the present invention is not limited to the embodiments disclosed below, but may be configured in various different forms, so that the disclosure of the present invention is complete and those of ordinary skill in the technical field to which the present invention pertains ( Hereinafter, it is provided in order to completely inform the scope of the invention to the "common engineer").

According to an embodiment of the present invention, by filling the pores of the solid electrolyte with a polymer material, it is possible to manufacture a thin solid electrolyte having high strength and density.

The effects of the present invention are not limited to the above-described effects, and the potential effects expected by the technical features of the present invention will be clearly understood from the following description.

1 is a view showing a method of manufacturing a solid electrolyte according to an embodiment of the present invention.
2A to 2C are views showing a solid electrolyte according to an embodiment of the present invention.
3 is a view showing a schematic diagram of a manufacturing process of a solid electrolyte according to an embodiment of the present invention.
4 is a diagram showing the properties of a solid electrolyte according to an embodiment of the present invention.
5 is a view showing an ionic conductivity graph of a solid electrolyte according to an embodiment of the present invention.
6A is a view showing the results of SEM-EDS analysis according to a conventional method for preparing a solid electrolyte.
6B to 6F are diagrams showing SEM-EDS analysis results according to an embodiment of the present invention.
7 is a diagram showing strength measurement of a solid electrolyte according to an embodiment of the present invention.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail.

The various features of the invention disclosed in the claims may be better understood in view of the drawings and detailed description. The apparatus, method, preparation method, and various embodiments disclosed in the specification are provided for illustration purposes. The disclosed structural and functional features are intended to enable a person skilled in the art to specifically implement various embodiments, and are not intended to limit the scope of the invention. The disclosed terms and sentences are intended to describe various features of the disclosed invention in an easy to understand manner, and are not intended to limit the scope of the invention.

In describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

Hereinafter, a method of manufacturing a solid electrolyte filled with a polymer material according to an embodiment of the present invention will be described.

1 is a view showing a method of manufacturing a solid electrolyte according to an embodiment of the present invention.

Referring to FIG. 1, step S101 is a step of impregnating a solid electrolyte in a solution in which a monomer is dissolved. In one embodiment, the solid electrolyte may be immersed in a solution in which a monomer is dissolved. In another embodiment, the solution in which the monomer is dissolved may be cast on a solid electrolyte.

In this case, referring to FIG. 2A, the solid electrolyte 201 before the steps S101 to S107 of the present invention are performed may be a solid electrolyte in which a phase is formed such as a pellet, not a powder form. In one embodiment, a precursor is added to a solvent to form a slurry, the formed slurry is dried to form a granule, and the resulting granules are compressed to form a solid compact, and then a solid compact is formed. The solid electrolyte 201 may be produced by sintering.

In another embodiment, the formed slurry may be tape-casted to generate a solid pallet, and then the solid pallet may be sintered to produce the solid electrolyte 201. Thereafter, referring to FIG. 2B, the solid electrolyte 201 may be impregnated in a solution 203 in which a monomer is dissolved.

Step S103 is a step of placing the solid electrolyte impregnated with the solution inside the vacuum chamber. In one embodiment, the solid electrolyte impregnated with the solution may be put into a vacuum chamber and then taken out of the vacuum chamber after a certain period of time (eg, 1 to 10 hours) elapses in a vacuum state. When the solid electrolyte is placed in a vacuum state, monomers can be introduced into the inner pores of the solid electrolyte and fill the inner pores. This is because, when the solid electrolyte is placed in a vacuum state, the air existing in the pores is removed so that the solution in which the monomers are dissolved can smoothly flow into the pores.

Step S105 is a step of heating the solid electrolyte filled with the monomers. As the solid electrolyte is heated, a polymer may be generated from monomers introduced into the internal pores of the solid electrolyte. That is, the monomer inside the pores may be polymerized through heating of the solid electrolyte. As described above, since the polymer itself cannot directly enter the pores due to its large molecular weight, the monomer is first introduced into the pores, and then a polymer is generated from the introduced monomer.

Step S107 is a step of polishing the polymer generated on the surface of the solid electrolyte. When the solid electrolyte is heated in step S105, not only the monomers filled in the pores inside the solid electrolyte but also the monomers located on the outer surface of the solid electrolyte are formed of a polymer, and thus a polymer layer may be formed on the outer surface of the solid electrolyte. Accordingly, as shown in FIG. 2C, the polymer layer generated on the surface of the solid electrolyte 205 filled with the polymer in the pores is removed through polishing.

Hereinafter, in the present disclosure, a method of manufacturing a solid electrolyte including at least one of steps S101 to S107 according to an embodiment of the present invention may be referred to as a polymer treatment process.

3 is a view showing a schematic diagram of a manufacturing process of a solid electrolyte according to an embodiment of the present invention.

Referring to FIG. 3, sodium ions or lithium ions move through the solid electrolyte 301 before polymer treatment according to the present invention, and water molecules (H ₂ O) may also pass through the pores 303.

As described above, the monomer filled in the pores 303 inside the solid electrolyte 301 is formed of the polymer 305 by the polymer treatment process according to an embodiment of the present invention.

In this case, the polymer 305 is also formed on the outer surface of the solid electrolyte 301 to form the polymer layer 307. The polymer layer 307 includes not only water molecules, but also sodium ions or lithium ions, and the solid electrolyte 301 Make it impossible to pass.

Accordingly, the polymer layer 307 formed on the outer surface of the solid electrolyte 301 is removed through the polishing process. Thereby, sodium ions or lithium ions can pass through the solid electrolyte 301, but since the pores 303 of the solid electrolyte 301 are filled with the polymer 305, water molecules can pass through the solid electrolyte 301. There will be no.

As described above, in the method of manufacturing a solid electrolyte prepared according to an embodiment of the present invention, the polymer is filled in the pores, thereby reducing the passage of water molecules and selectively passing only sodium ions or lithium ions. Solid electrolytes with high strength and density can be produced. Thus, the solid electrolyte prepared according to an embodiment of the present invention may be used for a secondary battery, and the secondary battery includes a method for preparing a solid electrolyte according to an embodiment of the present invention and a positive electrode current collector impregnated with a sodium-containing solution. It may be manufactured through the steps of forming a positive electrode part and forming a negative electrode part including a negative electrode current collector impregnated with an organic electrolyte.

4 is a diagram showing the properties of a solid electrolyte according to an embodiment of the present invention.

Referring to FIG. 4A, it can be seen that water molecules pass through a solid electrolyte 401 that has not been subjected to a conventional polymer treatment due to a high porosity.

Referring to (b) of FIG. 4, it can be confirmed that water molecules cannot pass through the solid electrolyte 403 after the polymer treatment according to the present invention because the polymer is filled in the pores. While removing the polymer layer on the outer surface, the solid electrolyte 403 may be partially polished to be thinly manufactured. In this case, since the pores of the solid electrolyte 403 are filled with the polymer, the solid electrolyte 403 having high strength and thinness can be manufactured.

In some embodiments, the porosity and true specific gravity of the solid electrolyte 401 not subjected to the conventional polymer treatment and the solid electrolyte 403 after the polymer treatment according to the present invention are shown in Equations 1 and 2, respectively. > Can be calculated as shown in <Table 1>.

Here, W1 is the weight of the solid electrolyte not impregnated with water, W2 is the weight of the solid electrolyte impregnated with water, and W3 is the weight of the solid electrolyte taken out after being impregnated with water.

Here, W1 is the weight of the solid electrolyte not impregnated with water, W2 is the weight of the solid electrolyte impregnated with water, and W3 is the weight of the solid electrolyte taken out after being impregnated with water.

Porosity True specific gravity Solid electrolyte before polymer treatment 6.62% 2.56 Solid electrolyte after polymer treatment 0.29% 2.88

Referring to <Table 1>, since the pores of the solid electrolyte 403 after the polymer treatment according to the present invention are filled with the polymer, it can be confirmed that the porosity is considerably reduced compared to the conventional solid electrolyte 401 before polymer treatment. On the other hand, it can be seen that the true specific gravity increases.

5 is a view showing an ionic conductivity graph of a solid electrolyte according to an embodiment of the present invention.

Referring to FIG. ⁵ , it can be seen that the ionic conductivity of the solid electrolyte before the polymer treatment is 2.8x10 ^-4 S/cm, and the ionic conductivity of the solid electrolyte after the polymer treatment according to the present invention is 9x10 ^-5 S/cm. That is, it can be seen that the polymer-treated solid electrolyte according to an embodiment of the present invention has improved ionic conductivity. This may be due to the fact that not only the polymer layer but also the solid electrolyte surface is polished through polishing, thereby reducing the thickness. However, after the polymer treatment according to the present invention, the thickness of the solid electrolyte becomes thinner to increase ionic conductivity, and at the same time, the polymer is filled in the pores, thereby increasing the strength.

6A is a view showing the results of SEM-EDS analysis according to a conventional method for preparing a solid electrolyte. Referring to FIG. 6, in the solid electrolyte before the polymer treatment, no polymer is observed in the pores. For example, in the case of using a carbon-based monomer, carbon is observed in the pores in the SEM-EDS image, but since the conventional solid electrolyte is not filled with polymers in the pores, the result of SEM-EDS analysis does not show carbon in the pores. can confirm.

On the other hand, FIGS. 6B to 6F are diagrams showing SEM-EDS analysis results according to an embodiment of the present invention. Referring to FIGS. 6B to 6F, it can be seen that the polymer is filled in the pores of the polymer-treated solid electrolyte according to the present invention. Even when observed at high magnification, it can be confirmed that the polymer is filled up to the inside of the fine pores. In particular, referring to FIG. 6E, it can be confirmed that the polymer is filled even in fine pores of 700 nm or less, and referring to FIG. 6F, it can be confirmed that the polymer is also filled in the grain boundary.

7 is a diagram showing strength measurement of a solid electrolyte according to an embodiment of the present invention.

Referring to FIG. 7, the strength of each solid electrolyte can be checked by measuring the flexural strength of the solid electrolyte before the conventional polymer treatment and the flexural strength of the solid electrolyte after the polymer treatment according to the present invention. For example, the solid electrolyte before the conventional polymer treatment is LATP (Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ ), and the solid electrolyte after the polymer treatment according to the present invention is an epoxy-based polymer filled in the pores. In the case of LATP, the flexural strength of each solid electrolyte can be measured as shown in <Table 2> using the following <Equation 3>.

는 굴곡강도, b는 고체 전해질의 너비, d는 고체 전해질의 두께, L은 고체 전해질의 길이를 의미한다.Where F is the force applied to the solid electrolyte,

Is the flexural strength, b is the width of the solid electrolyte, d is the thickness of the solid electrolyte, and L is the length of the solid electrolyte.

Bending strength Solid electrolyte before polymer treatment 8 Solid electrolyte after polymer treatment 47

Referring to <Table 2>, it can be seen that the solid electrolyte after the polymer treatment according to the present invention has about 6 times greater strength than the conventional solid electrolyte before the polymer treatment.

In one embodiment, the solid electrolyte according to the present invention includes a lithium ion conductive solid electrolyte, for example, NASICON-type solid electrolyte (Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , LAGP, etc. Other ion doping), LLTO-type solid electrolyte (Li _3x La _2/3-x TiO ₃ ), LISICON-type solid electrolyte (Li ₁₄ ZnGe ₄ O ₁₆ ), composite-type solid electrolyte ( LiI-Al ₂ O ₃ ), LiPON (Li _2.88 PO _3.73 N _0.14, Li ₃ PO _3.3 N _0.5 ), Thio-LISICON-type solid electrolyte (Li ₁₀ GeP ₂ S _12, Li ₁₀ SnP ₂ S _12, Li ₂ S `30P ₂ S ₅ ), garnet-type solid electrolyte (Li ₆ La ₂ BaTa ₂ O _12, Li ₇ La ₃ Zr ₂ O ₁₂ ).

-Al₂O₃), NaPS4 계열 고체 전해질(정방상(tetragonal phase) NaPS₄, 큐빅 상(cubic phase) NaPS₄ 등과 이의 혼합 및 타 이온 도핑 류)을 포함할 수 있다.In one embodiment, the solid electrolyte according to the present invention includes a sodium ion conductive solid electrolyte, for example, a solid electrolyte of a NASICON-based material (a _1+x Zr ₂ P _3-x Si _x O ₁₂ , 0< x <3 and doping material, NaMM'(PO4)3, M or M'= Na+, V3+, Nb3+, Ta3+), beta-alumina (

-Al ₂ O ₃ ), NaPS4 based solid electrolyte (tetragonal phase NaPS ₄ , cubic phase (cubic phase) NaPS _4, etc., and mixtures thereof and other ion dopings) may be included.

In one embodiment, the polymer material according to the present invention is an epoxy-based polymer, a polyethylene oxide, a PV (polyvinyl)-based polymer (polyvinyl chloride, polyvinyl butyl alcohol), PVDF (Polyvinylidene fluoride)-based polymer (PVDF, PVDF-HFP), PAN (Polyacrylonitrile)-based polymer, and PVA (Polyvinyl alcohol)-based polymer may be included.

The above description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made to those skilled in the art without departing from the essential characteristics of the present invention.

Accordingly, the embodiments disclosed in the present specification are not intended to limit the technical spirit of the present invention, but are intended to be described, and the scope of the present invention is not limited by these embodiments.

The scope of protection of the present invention should be interpreted by the claims, and all technical ideas within the scope equivalent thereto should be understood as being included in the scope of the present invention.

201: solid electrolyte
203: solution
205: solid electrolyte
301: solid electrolyte
303: Qigong
305: polymer
307: polymer layer
401: solid electrolyte
403: solid electrolyte

Claims (7)

(A) impregnating a solid electrolyte in a solution in which a monomer is dissolved;
(B) heating the solid electrolyte in which the monomer is filled in internal pores; And
(C) polishing a polymer generated on the surface of the solid electrolyte;
Including,
The polymer is generated from a monomer introduced into the solid electrolyte through the heating,
The monomer filled in the internal pores of the solid electrolyte is polymerized through the heating,
The molecular weight of the monomer is less than the molecular weight of the polymer,
Method for producing a solid electrolyte.
The method of claim 1,
Between steps (A) and (B),
Placing the solid electrolyte impregnated in the solution in a vacuum chamber;
Further comprising,
Method for producing a solid electrolyte.
delete The method of claim 1,
The step (A),
Casting a solution in which the monomer is dissolved in a solid electrolyte;
Containing,
Method for producing a solid electrolyte.
The method of claim 1,
Before step (A),
Dissolving the monomer in a solvent;
Further comprising,
Method for producing a solid electrolyte.
The method of claim 1,
Before step (A),
Adding a precursor to a solvent to form a slurry;
Drying the slurry to produce granules;
Compressing the granules to produce a solid compact; And
Sintering the solid compact to produce the solid electrolyte;
Further comprising,
Method for producing a solid electrolyte.
Forming the solid electrolyte of claim 1;
Forming a positive electrode portion including a positive electrode current collector impregnated with a sodium-containing solution; And
Forming a negative electrode part including a negative electrode current collector impregnated with an organic electrolyte;
Containing,
Method of manufacturing a secondary battery.

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