KR101946148B1 - Preparing method of anode for integrated lithium-air battery with micro-pattern - Google Patents

Abstract

The present invention relates to a method of fabricating an anode for a lithium-air battery having a micropattern formed therein, the method comprising: preparing a catalyst layer; Preparing a laminate by sequentially laminating the prepared catalyst layer and a metal mold having a lattice pattern engraved on the gas diffusion layer; And forming a micropattern on the surface of the catalyst layer and the gas diffusion layer by removing the metal mold located above the stacked body after pressing the prepared stacked body. ≪ / RTI >
The positive electrode for an integrated lithium-air battery in which a three-dimensional micropattern produced according to the present invention is formed can induce an improvement in energy density and high output characteristics as compared with a positive electrode for a two-dimensional integrated lithium- There is an effect.
In addition, since the positive electrode for a lithium-air battery having a three-dimensional micropattern formed according to the present invention has a gas diffusion layer and a catalyst layer pressed through a pressing process, it is not necessary to include a binder in the gas catalyst layer. The adhesive force can be further improved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing an anode for an integrated lithium-

The present invention relates to a method of manufacturing an anode for a lithium-air battery in which a micropattern is formed which can increase the surface area due to the formation of a micropattern on the surface of the gas diffusion layer to improve the electrochemical performance.

The lithium-air battery is a battery with a theoretical energy density (3000 Wh / kg or more) that is 2 to 3 times higher than that of a conventional lithium-ion battery. It is a future- .

In addition, it exhibits efficiency in correspondence with fuel such as gasoline, can remarkably reduce the volume and weight of the battery, is environment-friendly, and has high stability.

However, since the gas diffusion layer constituting the lithium-air battery has a planar two-dimensional structure, there is a limit to increase the area of the catalyst per area, and the conventional lithium-air battery has a problem of low power output In order to improve this, expensive noble metals (Pt, Pd, Ru) have been used.

Therefore, it is urgent to research and develop a positive electrode for a lithium-air battery which can improve a high output characteristic by increasing the area of the gas diffusion layer and using a noble metal.

Korean Patent Publication No. 2016-0068415

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lithium ion secondary battery capable of exhibiting high energy density and high output characteristics by forming a micropattern having a three-dimensional three-dimensional structure on a surface of a catalyst layer and a gas diffusion layer through a pressing process using a metal mold having a grid- And an object of the present invention is to provide a method for manufacturing an anode for an air battery.

According to an aspect of the present invention, Preparing a laminate by sequentially laminating the prepared catalyst layer and a metal mold having a lattice pattern engraved on the gas diffusion layer; And forming a micropattern on the surface of the catalyst layer and the gas diffusion layer by removing the metal mold located above the stacked body after pressing the prepared stacked body. ≪ / RTI >

The positive electrode for an integrated lithium-air battery in which a three-dimensional micropattern produced according to the present invention is formed can induce an improvement in energy density and high output characteristics as compared with a positive electrode for a two-dimensional integrated lithium- There is an effect.

In addition, since the positive electrode for a lithium-air battery having a three-dimensional micropattern formed according to the present invention has a gas diffusion layer and a catalyst layer pressed through a pressing process, it is not necessary to include a binder in the gas catalyst layer. The adhesive force can be further improved.

Fig. 1 shows optical images (a and d) for observing patterns of metal molds made of duralumin, sectional images (b and c) of each sample using SEM, and surface images (e, f FIG.
2 is a graph showing the charging / discharging curves at various current densities of M-GDL (a) prepared in Example 1 and P-GDL (b) prepared in Comparative Example 1, Graph (c), and graph (d) comparing voltages at 250 mAh / g of each sample; And
3 shows the cyclic voltammetry (CV) (a) and linear sweep voltammetry (LSV) (b) of each sample conducted at a scan rate of 0.5 mV / s, FIG.

Hereinafter, a method for manufacturing a positive electrode for an integrated lithium-air battery in which the micropattern of the present invention is formed will be described in more detail.

The inventors of the present invention have found that when an integral lithium-air battery anode in which a micropattern is formed on the surface of a catalyst layer and a gas diffusion layer through a pressing process using a metal mold with a grid pattern is used for a lithium- It is possible to exhibit high energy density and high output characteristics when compared with an air cell.

The present invention provides a method for preparing a catalyst, comprising: preparing a catalyst layer; Preparing a laminate by sequentially laminating the prepared catalyst layer and a metal mold having a lattice pattern engraved on the gas diffusion layer; And forming a micropattern on the surface of the catalyst layer and the gas diffusion layer by removing the metal mold located above the stacked body after pressing the prepared stacked body. ≪ / RTI >

The catalyst layer may be any one of carbon nanofibers and carbon nanotubes, but is not limited thereto.

Particularly, the carbon nanofibers in the catalyst layer can be produced by electrospinning.

More specifically, the step of preparing the carbon nanofibers may include a step of mixing an electrospinning solution prepared by mixing polyacrylonitrile and N, N-dimethylformamide at a weight ratio of 1: 5 to 15, The polyacrylonitrile nanofiber is heated to 200 to 300 DEG C under an atmospheric environment, and then the polyacrylonitrile nanofiber is heated to a temperature of 2 to 4 And a step of heat treating the impregnated polyacrylonitrile nanofibers under a nitrogen atmosphere for 2 to 4 hours to 800 to 1000 ° C to produce carbon nanofibers But is not limited thereto.

The metal mold may be made of duralumin, but is not limited thereto.

The metal mold may be patterned with a lattice pattern using an electrical discharge machining (EDM) process.

The gas diffusion layer may be any one selected from the group consisting of activated carbon, carbon black, carbon cloth, and carbon paper, but is not limited thereto.

In the step of forming the micropattern on the surface of the catalyst layer and the gas diffusion layer, the prepared laminate is pressurized at a pressure of 10 to 15 MPa for 3 to 10 minutes, and then the metal mold located on the upper part of the laminate is removed, The micropattern can be formed on the surface, but is not limited thereto.

Specifically, when the prepared laminate is pressed at a pressure of less than 10 MPa, there is a problem that a pattern of a sufficient shape is not engraved. Also, when the prepared laminate is pressed at a pressure exceeding 15 MPa, It is preferable to pressurize the prepared laminate at a pressure of 10 to 15 MPa. In particular, when the formation of a proper pattern and the structural stability of the gas diffusion layer are taken into consideration, the prepared laminate is pressed at a pressure of 13 MPa It is more preferable to pressurize it.

Specifically, when the prepared laminate is pressed for less than 3 minutes, the engraved pattern is regenerated If the prepared laminate is pressurized for more than 10 minutes, it may cause a problem of damaging the gas diffusion layer. Therefore, it is preferable to pressurize the prepared laminate for 3 to 10 minutes, And the structural stability of the gas diffusion layer It is more preferable to press the prepared laminate for 5 minutes.

Hereinafter, a method of manufacturing an integral positive electrode for a lithium-air battery in which a micropattern according to the present invention is formed will be described in more detail with reference to the following examples. However, the present invention is not limited by these examples.

<Example 1> Preparation of a positive electrode for a lithium-air battery having a micro pattern formed therein

1. Preparation of carbon nanofiber as catalyst layer

Carbon nanofibers were prepared by electrospinning.

First, 1 g of polyacrylonitrile (hereinafter referred to as 'PAN', MW = 150,000) and 10 g of N, N-Dimethylformamide (hereinafter referred to as 'DMF',> 99.8% A homogeneous electric spinning solution was prepared using an East Mixer (East-West Science).

The prepared electrosurgical fluid was filled into a 10 ml plastic syringe with a 23-gauge needle and the pump was set to be injected at a rate of 20 l / min during electrospinning.

The polyacrylonitrile nanofiber was obtained by applying an aluminum foil (collector foil) to a collector surface at a point 20 cm from the end of the syringe and electrospinning the applied voltage at 20 kV .

In order to remove impurities of the polyacrylonitrile nanofiber, the sheet was heated to 250 DEG C in an atmospheric environment at a rate of 1 DEG C / min, and then held for 3 hours.

Thereafter, the carbonization process for crystallization of the sample was conducted at a temperature raising rate of 5 ° C / min, and then heat-treated at 900 ° C for 3 hours in a nitrogen atmosphere to prepare a carbon nanofiber as a catalyst layer.

2. Manufacture of positive electrode for integrated lithium-air battery in which a micropattern is formed on the surface of catalyst layer, catalyst layer and gas diffusion layer

Carbon nanofibers as a catalyst layer were laminated on a carbon paper (Toray TGP-H-060) as a gas diffusion layer, and metal molds of a duralumin material having a lattice pattern engraved on the top were laminated to prepare a laminate.

Thereafter, the mixture was pressurized at a pressure of 13 MPa for 5 minutes, and the metal mold was removed to produce an integral lithium-pneumatic battery anode (hereinafter referred to as "M-GDL") micropatterned on the surface of the carbon nanofibers serving as the catalyst layer.

&Lt; Comparative Example 1 > Preparation of a positive electrode for an integrated lithium-air battery not including a micropattern

The same conditions as those of Example 1 were obtained except that a lithium-air battery anode (hereinafter referred to as "P-GDL") was produced by using a duralumin-based metal mold in which a lattice pattern was not formed.

<Experimental Example 1> Structural analysis of the anode for lithium-air battery of Example 1 prepared in Example 1 and Comparative Example 1

1, optical images (a, d) were observed using an optical microscope (Nicon TS100) to observe patterns of metal molds made of duralumin.

1 (a) is a view showing a surface optical image of a metal mold made of duralumin. Specifically, it was confirmed that a lattice pattern was engraved on the surface of the metal mold, and an enlarged image of the pattern was shown in Fig. 1 (d).

The lattice pattern was examined in detail. It was confirmed that the rectangle had a rectangular shape in the center and the straight lines formed a relief shape in the periphery.

1 (b) and 1 (c) are cross-sectional images (b, c) of respective samples using a scanning electron microscope (SEM) (JEOL-7800).

Specifically, the M-GDL sample prepared in Example 1 confirmed that the shape of each cross-section was not planar and a rugged three-dimensional structure was formed by the pattern (see Fig. 1 (b) The cross section of the P-GDL sample prepared by this method was observed in a plane cross section (see Fig. 1 (c)).

1 (e) and 1 (f) are diagrams showing surface images (e, f) of each sample using an SEM.

Specifically, the M-GDL sample prepared in Example 1 was confirmed to have a shape of a center-pitted lattice (see FIG. 1 (e)), and the P-GDL sample prepared in Comparative Example 1 was flat carbon paper (See Fig. 1 (f)).

From the above results, it was confirmed that the pattern engraved in the metal mold by the electrical discharge machining (EDM) process was directly embedded in the carbon paper through the patterning process.

Also, the scale bar of the image shows that the pattern of each sample was fabricated with a micro-scale size.

EXPERIMENTAL EXAMPLE 2 Electrochemical Characteristic Analysis of the Integrated Li-air Battery Cathode Prepared by Example 1 and Comparative Example 1

1. Electrochemical test

The battery was dried in an oven at 110 DEG C for 24 hours to remove moisture from the positive electrode for the integrated lithium-air battery produced in Example 1 and Comparative Example 1. [

After drying, it was assembled in a groove box maintained with pure argon gas, and lithium metal was used as a counter electrode.

As the electrolyte, a bis (trifluoromethane) sulfonamide lithium salt (LiTFSI) and a triethylene glycol dimethyl ether (LiTFSI) acting as a solvent are used as a salt for lithium ion migration. TEGDME) was used.

The assembled lithium - air cells were controlled for moisture content below 5%, and stabilized for one day in a case where oxygen was saturated, and then the electrochemical characteristics were analyzed.

2. Charge / discharge curve analysis

FIG. 2 is a graph showing the current density (100 mA / g, 200 mA / g, 500 mA / g) of the M-GDL (a) prepared in Example 1 and the P- 1000 mA / g, and 2000 mA / g).

2 (a) and 2 (b), the M-GDL produced in Example 1 and the M-GDL produced in Comparative Example 1 due to the characteristics of the battery exhibited by increasing the resistance with increasing current density It was confirmed that the electric potential of the discharge curve gradually decreased as the current density value was increased in the P-GDL.

3. Analysis of discharge curves at high current densities of 1000 mA / g and 2000 mA / g

2 (c) is a graph showing a discharge graph of the M-GDL prepared in Example 1 and the P-GDL prepared in Comparative Example 1, which proceed at a high current density of 1000 mA / g and 2000 mA / g .

Referring to FIG. 2 (c), the scale of the y-axis is varied in order to closely observe the change of the discharge curve at a high current density of 1000 mA / g and 2000 mA / g.

Specifically, the difference between the two samples of the M-GDL prepared in Example 1 and the P-GDL prepared in Comparative Example 1 clearly appeared. The decrease in dislocation at 2000 mA / g, which is a high current density, was much less than that of the P-GDL sample prepared by Comparative Example 1 with the M-GDL sample prepared by Example 1.

On the other hand, the P-GDL sample prepared in Comparative Example 1 had discharge cut-off potential reduced to 2.2 V before 500 mAh / g, whereas the M-GDL sample prepared in Example 1 It was confirmed that the discharging capacity was increased by continuing the discharge even after 500 mAh / g.

4. Analysis of rate-limiting characteristics

FIG. 2 (d) is a graph showing the relationship between the discharge capacity 1/2 and the discharge capacity at each current density value, in order to numerically examine the rate characteristics of the M-GDL produced by Example 1 and the P- 2 shows the potential at the point (250 mAh / g).

Referring to FIG. 2 (d), it was confirmed that the M-GDL sample prepared in Example 1 had a high potential at all current densities.

Also, at the current density of 2000 mA / g, the M-GDL sample prepared by Example 1 was 0.543 V, as compared with the theoretical discharge voltage of 2.96 V of the lithium-air battery, and the P-GDL The sample was measured for an overvoltage of 0.7 V. It was found that the M-GDL sample prepared according to Example 1 exhibited a low overvoltage of 23.5% as compared with the P-GDL sample prepared according to Comparative Example 1, I could.

5. Cyclic voltammetry (CV) analysis

CV analysis was performed at a scan rate of 0.5 mV / s to confirm the performance of the M-GDL prepared in Example 1 and the P-GDL prepared in Comparative Example 1 as a catalyst.

3 (a), the M-GDL sample prepared in Example 1 has a higher oxygen reduction reaction (ORR) peak current than the P-GDL sample prepared in Comparative Example 1 And it was confirmed that it represents density.

The high current density represents the degree of reaction at that voltage.

Specifically, when comparing the highest current density values of the M-GDL sample prepared in Example 1 with the P-GDL sample prepared in Comparative Example 1, the M-GDL sample prepared in Example 1 had a peak value of 2.266 A / g, and the P-GDL sample prepared in Comparative Example 1 showed a current density of 0.834 A / g.

That is, the current density of the M-GDL sample prepared in Example 1 was about 2.71 times higher than that of the P-GDL sample prepared in Comparative Example 1.

6. Linear sweep voltammetry (LSV) analysis

LSV analysis was performed to confirm the relative reaction rates of the M-GDL prepared in Example 1 and the P-GDL sample prepared in Comparative Example 1, and the results are shown in FIG. 3 (b).

Referring to FIG. 3 (b), the potentials of the M-GDL prepared in Example 1 and the P-GDL sample prepared in Comparative Example 1 at a current density of -0.1 A / g were analyzed, The M-GDL sample prepared by 1 had a potential value of 2.697 V, and the P-GDL sample prepared by Comparative Example 1 had a potential value of 2.671 V.

That is, it was confirmed that the M-GDL sample prepared by Example 1 exhibited a high set potential of about 26 mV.

The high initiation potential is a measure of the rate of the reaction. From these results it can be seen that the M-GDL sample prepared according to Example 1 having a pattern of three-dimensional structure has an increased surface area, And thus showed improved performance in advanced electrochemical analysis.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It is to be understood that various modifications and changes may be made without departing from the scope of the appended claims.

Claims (5)

Preparing a catalyst layer;
Preparing a laminate by sequentially laminating the prepared catalyst layer and a metal mold having a lattice pattern engraved on the gas diffusion layer; And
Forming a micropattern on the surface of the catalyst layer and the gas diffusion layer by removing the metal mold located above the stacked body after pressing the prepared stacked body;
Wherein the micropattern is formed on the surface of the anode. The method according to claim 1,
Wherein the catalyst layer comprises:
Carbon nanofibers, and carbon nanotubes, wherein the micropattern is formed on the surface of the anode. The method according to claim 1,
Wherein the metal mold comprises:
A method for manufacturing a positive electrode for a lithium-air battery in which a micropattern is formed, which is formed of a duralumin material. The method according to claim 1,
The gas diffusion layer
Wherein the positive electrode is any one selected from the group consisting of activated carbon, carbon black, carbon cloth, and carbon paper. The method according to claim 1,
Forming a micropattern on the surface of the catalyst layer and the gas diffusion layer,
Characterized in that the prepared laminate is pressurized at a pressure of 10 to 15 MPa for 3 to 10 minutes and then a metal mold located on the laminate is removed to form a micropattern on the surface of the catalyst layer and the gas diffusion layer, Wherein the positive electrode and the negative electrode are made of a metal.

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