KR101675479B1 - Manufacturing method for complex catalyst for rechargeable metal-air battery - Google Patents

Abstract

More particularly, the present invention relates to a method for producing a silk fiber solution by dissolving a silk fiber in a solvent; Introducing a metal precursor and carbon black into the silk fiber solution; Stirring the silk fiber solution charged with the metal precursor and the carbon black to prepare a catalyst precursor; And heat-treating the catalyst precursor to obtain a catalyst. The present invention also provides a method for producing a composite catalyst for a metal air cell.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing a composite catalyst for a metal air cell,

And a method for producing a composite catalyst for a metal air cell.

A metal air cell is a cell that uses oxygen as an energy source by reducing oxygen in the air at the anode.

Such metal air cells are attracting attention as a next generation battery and have a higher output and energy density than a primary battery or a lithium ion battery and are expected to play an important role in developing an electric vehicle.

On the other hand, metal air cells can be broadly classified into lithium air cells and zinc air cells depending on the type of metal used.

In this regard, lithium metal has the potential to react with water and explode, so it is difficult to control the moisture in the manufacture of lithium air cells.

On the other hand, the zinc metal is not explosive, and the manufacturing process of the zinc air cell using the zinc metal is relatively safe. In addition, since it is produced in ordinary air at normal temperature, it is also advantageous in terms of production cost.

However, despite these merits, the electrochemical oxidation-reduction reaction occurring in the anode (i.e., the air electrode) of the zinc air cell proceeds very slowly, so that charging and discharging of the battery are very difficult.

That is, the reaction in which oxygen is reduced at the air electrode of the zinc air cell is a rate determining step, and it is necessary to increase the reaction rate using an oxygen reduction catalyst.

Although the best catalyst known to date is known as platinum, it is disadvantageous in view of the high price and scarcity of platinum, and exhibits poor characteristics when methanol, which is not an alkali solution, is used as an electrolyte solution.

Therefore, in order to commercialize a metal air cell, it is required to have an inexpensive catalyst having a performance as high as that of platinum, and various studies have been carried out for this purpose, but the fundamental limit still can not be overcome.

The present inventors intend to provide a silk-fiber-based iron-nitrogen-carbon catalyst in order to solve the above-mentioned problems. The details of this are as follows.

According to an embodiment of the present invention, a method for producing the composite catalyst for a metal air cell can be provided by a simple process using relatively inexpensive raw materials, stirring the raw materials, and then performing heat treatment.

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According to the manufacturing method described below, carbonized fibril; Carbonized carbon black; And a metal; and a composite catalyst for a metal air cell.

Specifically, the carbonized fibril may include amorphous carbon and nitrogen doped to the amorphous carbon.

Wherein the amorphous carbon forms a skeleton, a part of the doped nitrogen is combined with the carbonized carbon black, another part of the doped nitrogen is combined with a part of the metal, and the metal May be in a form combined with the carbonized carbon black.

In addition, the content of doped nitrogen in the composite may be expressed as 1.3 to 1.6 wt%, as a weight percentage of the doped nitrogen to the composite.

Meanwhile, the ratio of the carbonized fibers and the metal in the composite may be expressed as 6.67: 100 to 15: 100 in terms of the weight ratio of the carbon to the carbonized fibers.

Independently, the proportion of the carbonized fibril fibers and the carbonized carbon black in the composite may be expressed as a weight ratio of the carbonized carbon black to the carbonized fibril in a ratio of 6.67: 100 to 15: 100 have.

A description of each component in the composite is as follows.

The metal may be at least one selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), and combinations thereof.

The carbonized carbon black may be carbonized ketjen black.

In one embodiment of the present invention, there is provided a method of making a silk fiber, comprising: dissolving the silk fiber in a solvent to produce a silk fiber solution; Introducing a metal precursor and carbon black into the silk fiber solution; Stirring the silk fiber solution charged with the metal precursor and the carbon black to prepare a catalyst precursor; And heat treating the catalyst precursor to obtain a catalyst. The present invention also provides a method for producing a composite catalyst for a metal air cell.

Specifically, the step of heat-treating the dried catalyst precursor to obtain a catalyst is as follows.

The heat treatment may be performed in a temperature range of 850 to 950 캜.

Independently, from 1 to 3 hours.

It may also be performed in an inert gas atmosphere.

Meanwhile, a step of producing a catalyst precursor by stirring the silk fiber solution into which the metal precursor and the carbon black have been introduced will be described.

This may be to adsorb the metal contained in the metal precursor and the carbon black to the surface of the silk fiber.

Alternatively, it may be carried out at a stirring speed of 100 to 500 rpm.

It may also be carried out for 5 to 15 minutes.

The steps of dissolving the silk fibers in a solvent to produce a silk fiber solution are as follows.

The content of silk fibers in the silk fiber solution may be expressed as 0.99 to 1.48 wt%, as a weight% of the silk fiber with respect to the total weight of the silk fiber solution.

In addition, the silk fiber is nitrogen-doped, and the content of doped nitrogen in the silk fiber may be 0.01 to 0.02% by weight, as a weight percentage of the doped nitrogen to the silk fiber.

In addition, the step of injecting a metal precursor and carbon black into the silk fiber solution may include: injecting and dispersing the metal precursor into the silk fiber solution; And injecting the carbon black into the silk fiber solution in which the metal precursor is dispersed.

The amount of the metal precursor to be added is in the range of 6.67: 100 to 15: 1, preferably 5: 1 to 5: 1, in terms of the weight ratio of the metal precursor to the silk fibers in the silk fiber solution. 100 < / RTI >

In addition, in the step of injecting carbon black into the silk fibrous solution in which the metal precursor is dispersed and stirring the carbon black, the amount of the carbon black to be added is in the range of 6.67: 100 to 15: 100.

Mixing the silk fiber solution with the metal precursor and the carbon black to produce a catalyst precursor; Thereafter, the catalyst precursor may be dried.

The drying may be performed at a temperature ranging from 90 to 100 캜.

Independently, from 12 to 24 hours.

In addition, each raw material used in the above production method will be described as follows.

The metal precursor may be at least one selected from the group consisting of metal acetylacetonate, metal acetate, and combinations thereof.

The metal forming the metal precursor may be at least one selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), and combinations thereof.

Further, the carbon black may be ketjen black.

The solvent may be at least one selected from the group consisting of water, ethanol, acetone, and combinations thereof.

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According to one embodiment of the present invention, it is possible to provide a composite catalyst for a metal air cell, wherein the reaction between the catalyst and oxygen is activated and high durability is ensured.

In one embodiment of the present invention, a method for producing a composite catalyst for a metal air cell having excellent performance as described above can be provided by a simple process.

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1A is a SEM photograph of a catalyst according to an embodiment of the present invention.
FIG. 1B is a TEM photograph of a catalyst according to an embodiment of the present invention (the inside photograph is the FFT result thereof).
1C is a TEM photograph of a catalyst according to an embodiment of the present invention.
FIG. 1D shows the FFT result for FIG. 1C.
2A and 2B are XRD analysis results of a catalyst according to an embodiment of the present invention.
3A to 3C are XPS analysis results of catalysts according to one embodiment and / or a comparative example of the present invention.
4A shows a linear scanning voltammogram of a cell according to one embodiment of the present invention and comparative examples.
FIG. 4B shows the hydrogen peroxide generation rate of the battery according to one embodiment of the present invention and the comparative examples.
FIG. 4C shows a result of cyclic voltammetry analysis of a battery according to an embodiment of the present invention.
FIG. 4D shows the methanol resistance test results of the battery according to one embodiment of the present invention and comparative examples.
4 d to f show the result of electron mapping analysis of the catalyst according to an embodiment of the present invention.
5A is a graph showing output densities according to current density for a battery according to an embodiment of the present invention and comparative examples.
5B and 5C are graphs showing discharge characteristics of a battery according to an embodiment of the present invention and comparative examples. Specifically, the discharge current in FIG. 5B is 50 mA / cm ² , and the discharge current in FIG. 5C is 25 mA / cm ² .

Hereinafter, embodiments of the present invention will be described in detail. However, it should be understood that the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

According to one embodiment of the invention, carbonized fibrils; Carbonized carbon black; And a metal; and a composite catalyst for a metal air cell.

This is because, compared to a commercialized platinum catalyst, it is possible to further improve the rate at which oxygen is reduced at the anode, to secure a considerable durability, Catalyst.

In the case of a general zinc air cell, the electrode is composed of an anode where oxygen is reduced (that is, an air electrode) and a cathode where zinc is oxidized. There is a separator for separating the electrolyte and an electrolyte for facilitating the movement of ions.

Specifically, in the cathode, electrons are generated as the zinc metal is oxidized to zinc divalent ions, and the electrons move through the external conductor and react with each other while meeting the oxygen, so that the reduction reaction of oxygen occurs.

The reactions occurring in the anode and cathode of the metal air cell are represented by the chemical reaction formula as follows.

[Anode reaction] O ₂ + 2H ₂ O + 4e ^- → 4OH ^-

[Negative electrode reaction] Zn → Zn ^{2 +} + 2e ^-

Zn ^{2 +} + ₄ OH ^{- -} > Zn (OH) ₄ ^2-

Zn (OH) ₄ ^2- → ZnO + H ₂ O + 2OH ^-

However, when only a positive electrode to which no catalyst is applied is used, the positive electrode reaction is not efficiently performed. For this reason, in order to increase the overall efficiency of the metal air cell, it is important to make the oxygen reduction reaction in the anode relatively slow in the reaction rate.

To this end, the present inventors intend to activate the reduction reaction of oxygen by developing a catalyst applied on the anode. In addition, since each component in the composite is less expensive than platinum, it is also advantageous in terms of cost.

Hereinafter, the composite catalyst for a metal air cell provided in one embodiment of the present invention will be described in detail.

The carbonized fibril may comprise amorphous carbon and nitrogen doped to the amorphous carbon.

In this regard, the silk fibers may be any one selected from fibron or sericin. The fibron consists of three amino acids, glycine, alanine, and serine, which, when carbonized, can form amorphous carbon and doped nitrogen therein.

Wherein the amorphous carbon forms a skeleton, a part of the doped nitrogen is combined with the carbonized carbon black, another part of the doped nitrogen is combined with a part of the metal, and the metal May be in a form combined with the carbonized carbon black.

The composite having such a shape may not only have a high durability but also have an excellent electrochemical activity due to an increase in the area where the oxygen reduction reaction takes place.

Specifically, by forming the skeleton of the amorphous carbon in the carbonized fibril, the durability of the catalyst can be secured even when the electrolyte of the battery is an alkali solution.

Further, a portion of the doped nitrogen may be present in four forms of pyridinic, pyrrolic, graphitic, or oxidized nitrogen in association with the carbonized carbon black . Each of these forms is an effective form for the reduction reaction of oxygen. Specifically, when the value of the oxidized nitrogen amount relative to the pyridinic nitrogen is 1.13 to 1.52, the reduction reaction of oxygen can be more excellent.

Further, another part of the doped nitrogen may be combined with a part of the metal, and another part of the metal may be combined with the carbonized carbon black, thereby providing a wide catalytic reaction area. For example, when the metal is iron (Fe), Fe ₃ C and FeN ₄ can be formed by the bonding.

At this time, the content of the doped nitrogen may be expressed as 1.3 to 1.6 wt%, as a weight percentage of the doped nitrogen to the composite.

In such a range, an oxygen reduction reaction is actively effected. However, when nitrogen is doped in an excess amount exceeding 1.6 wt%, the oxygen reduction reaction is rather deteriorated. When the amount is less than 1.3 wt%, the doped nitrogen There is a problem that the content thereof is too small to expect the effect, so that the amount of nitrogen doping is limited as described above.

The ratio of the carbonized fibers and the metal in the composite may be 6.67: 100 to 15: 100 in terms of the weight ratio of the iron to the silk fiber.

Within this range, there is an effect that the oxygen reduction reaction described above is improved. However, when the metal is contained in an excess amount exceeding the weight ratio, there is a problem that the oxygen reduction reaction is deteriorated. In addition, when the metal is contained in the weight ratio less than the above-mentioned weight ratio, the content of the doped nitrogen or the carbonized carbon black is small so that the place for causing the above-mentioned oxygen reduction reaction is reduced. Accordingly, the content ratio of carbonized fibers and metal is limited as described above.

Independently, the proportion of the carbonized fibril fibers and the carbonized carbon black in the composite may be expressed as a weight ratio of the carbonized carbon black to the carbonized fibril in a ratio of 6.67: 100 to 15: 100 have.

When the carbonized carbon black is contained in an amount exceeding the above-mentioned weight ratio, there is a problem of reduction of the oxygen reduction reaction due to reduction of sites causing the oxygen reduction reaction When the carbon black is contained in an amount less than the above-mentioned weight ratio, there is also a problem of a reduction in the reaction due to a decrease in the number of sites that cause an oxygen reduction reaction. As a result, the ratio of the carbonized fibers and the carbonized carbon black is limited Come on.

A description of each component in the composite is as follows.

The metal is not particularly limited as long as it can combine with the doped nitrogen or the carbonized carbon black to exhibit the above-mentioned effects, as described above.

For example, the metal may be at least one selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), and combinations thereof.

The carbonized carbon black is not particularly limited as long as it can combine with the metal and the doped nitrogen to exhibit the above-mentioned effects.

For example, the carbonized carbon black may be carbonized ketjen black.

Specifically, in one embodiment of the present invention, there is provided a method for producing a silk fiber, comprising: dissolving a silk fiber in a solvent to produce a silk fiber solution; Introducing a metal precursor and carbon black into the silk fiber solution; Stirring the silk fiber solution charged with the metal precursor and the carbon black to prepare a catalyst precursor; And heat treating the catalyst precursor to obtain a catalyst. The present invention also provides a method for producing a composite catalyst for a metal air cell.

This is a method by which the above-described excellent catalyst can be produced by a simple process using relatively inexpensive raw materials and stirring these raw materials and then heat-treating them.

Hereinafter, a method for producing a composite catalyst for a metal air cell, which is provided in one embodiment of the present invention, will be described in detail, and a description overlapping with the above description will be omitted.

The step of heat-treating the dried catalyst precursor to obtain a catalyst is as follows.

As will be described later, the dried catalyst precursor may be a metal contained in the metal precursor and the carbon black adsorbed on the surface of the silk fiber, and the composite may contain doped nitrogen.

At this time, by the heat treatment, the silk fibers and the carbon black may be carbonized, respectively. Furthermore, the carbonized fibers, the carbonized carbon black, and the metal contained in the metal precursor may be synthesized using the same catalyst as the above-mentioned complex.

Specifically, the silk fibers are carbonized to form amorphous carbon and doped nitrogen, and the amorphous carbon becomes a skeleton of the catalyst, and a part of the doped nitrogen is converted into carbonized carbon black And the other part of the doped nitrogen is combined with a part of the metal, and another part of the metal can be combined with the carbonized carbon black.

In this case, the content of doped nitrogen in the composite can be controlled through the heat treatment, whereby the combined form of the doped nitrogen and the carbonized carbon black can be controlled. Specifically, the value of the oxidized nitrogen amount relative to the pyridinic nitrogen can be controlled to be 1.13 to 1.52, which can be controlled by controlling the temperature of the heat treatment to control the content of the doped nitrogen and the ratio of the carbon bonded thereto Can be achieved.

In addition, the composite having the above-mentioned shape may not only have a high durability, but also have a place where oxygen reduction reaction takes place and have excellent electrochemical activity. The detailed description thereof has been described above, so it is omitted.

At this time, the heat treatment may be performed at a temperature ranging from 850 to 950 ° C.

However, when the heat treatment is performed at a temperature exceeding 950 占 폚, there is a problem that the content of doped nitrogen in the silk fiber is reduced and the reduction reaction site of oxygen is reduced. When the temperature is less than 850 占 폚, The content of nitrogen is excessively increased, and the oxygen reduction reaction is rather inefficient, which limits the heat treatment temperature as described above.

Independently of this, the heat treatment may be performed for 1 to 3 hours.

However, if it exceeds 3 hours, there is a problem that the catalyst structure is destroyed due to high temperature. In case of less than 1 hour, there is a problem that carbonization of the silk fiber occurs incompletely, thereby limiting the heat treatment time as described above.

It may also be performed in an inert gas atmosphere.

This is to block as much as possible oxides which may be produced by the influence of oxygen gas.

Meanwhile, a step of producing a catalyst precursor by stirring the silk fiber solution into which the metal precursor and the carbon black have been introduced will be described.

This may be adsorption of the metal forming the metal precursor and the carbon black on the surface of the silk fiber, and may be continuously separated from the solvent in the solution.

Alternatively, it may be carried out at a stirring speed of 100 to 500 rpm.

However, there is a problem that the solution is difficult to control at a high speed exceeding 500 rpm, and the solution is not uniformly stirred at a speed lower than 100 rpm, so that the stirring speed is limited as described above.

Further, the stirring may be performed for 5 to 15 minutes.

This means that the metal forming the metal precursor and the carbon black are adsorbed on the surface of the wool fiber and completely separated from the solvent. If stirring is performed for less than 5 minutes, the separation is incomplete, There is a problem that the phase-separated material is rather incompletely distributed.

On the other hand, the step of dissolving the silk fiber in a solvent to produce a silk fiber solution is explained as follows.

The content of silk fibers in the silk fiber solution may be expressed as 0.99 to 1.48 wt%, as a weight% of the silk fiber with respect to the total weight of the silk fiber solution.

If the amount of the amorphous carbon is more than 1.48 wt%, there is a problem that the solvent is contained in an excessively small amount and the solution is not uniformly mixed. When the amount is less than 0.99 wt%, the amount of amorphous carbon produced by carbonization of the silk fiber is decreased , The content of the silk fibers in the silk fibers is limited as described above.

In addition, the silk fiber is nitrogen-doped, and the content of doped nitrogen in the silk fiber may be 0.01 to 0.02% by weight, as a weight percentage of the doped nitrogen to the silk fiber.

By using the nitrogen-doped stranded fiber as a raw material, doped nitrogen may also be contained in the composite. However, when the content of doped nitrogen in the silk fibers exceeds 0.02% by weight, the above-mentioned oxygen reduction reaction sites are not optimized. When the content is less than 0.01% by weight, the oxygen reduction reaction sites There is a problem that the content of doped nitrogen in the silk fibers is limited as described above.

In addition, the step of injecting a metal precursor and carbon black into the silk fiber solution may include: injecting and dispersing the metal precursor into the silk fiber solution; And injecting the carbon black into the silk fiber solution in which the metal precursor is dispersed.

The amount of the metal precursor to be added is in the range of 6.67: 100 to 15: 1, preferably 5: 1 to 5: 1, in terms of the weight ratio of the metal precursor to the silk fibers in the silk fiber solution. 100 < / RTI >

In addition, in the step of injecting carbon black into the silk fibrous solution in which the metal precursor is dispersed and stirring the carbon black, the amount of the carbon black to be added is in the range of 6.67: 100 to 15: 100.

The reason for limiting the respective weight ratios is as described above.

Mixing the silk fiber solution with the metal precursor and the carbon black to produce a catalyst precursor; Thereafter, the catalyst precursor may be dried.

The drying may be performed at a temperature ranging from 90 to 100 캜.

The structure of the catalyst precursor may be destroyed at a high temperature exceeding 100 ° C, and when the temperature is lower than 90 ° C, drying of the catalyst precursor is completed slowly, thereby limiting the drying temperature as described above.

Independently, from 12 to 24 hours.

If it exceeds 24 hours, there is a problem that the structure of the catalyst precursor is destroyed by high thermal energy, and when it is less than 12 hours, there is a problem that the catalyst precursor is insufficiently dried, Come on.

In addition, each raw material used in the above production method will be described as follows.

The metal precursor may be at least one selected from the group consisting of metal acetylacetonate, metal acetate, and combinations thereof.

The metal forming the metal precursor may be at least one selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), and combinations thereof.

Specifically, the metal precursor may be iron acetylacetonate, in which case the metal contained in the composite is iron.

Further, the carbon black may be ketjen black.

The solvent may be at least one selected from the group consisting of water, ethanol, acetone, and combinations thereof.

In connection with one embodiment of the present invention, a current collector, And a catalyst layer disposed on the current collector, wherein the catalyst layer is formed of a catalyst according to any one of the above-described methods.

Since the description of the catalyst is the same as that described above, a detailed description thereof will be omitted.

In addition, cathode; Separation membrane; And an electrolyte; wherein the anode comprises a current collector and a catalyst layer disposed on the current collector, and the catalyst layer is made of a catalyst according to any one of the above-described methods.

Since the description of the catalyst is the same as that described above, a detailed description thereof will be omitted.

Hereinafter, preferred embodiments of the present invention will be described. However, the following examples are only a preferred embodiment of the present invention, and the present invention is not limited to the following examples.

Example  One

(1) Preparation of Catalyst

According to one embodiment of the present invention, a catalyst was prepared as a composite comprising carbonized carbon black, metal, and carbonized silk fibroin. Hereinafter, a specific manufacturing method will be described in detail.

Iron acetylacetonate (Sigma Aldrich), an iron precursor, was prepared as a metal precursor, and ketjen black was used as a carbon black. Nitrogen-doped silk fiber was prepared, which contained 45 wt.% Of glycine, 29 wt.% Alanine, 12 wt.% Serine, 5 wt.% Tyrosine, valine and 2% by weight, and the remainder being aspartic acid, arginine, glutamic acid, isoleucine, leucine, phenylalanine, and threonine. By weight, respectively, to provide nitrogen doped by such amino acids.

0.3 g of the silk fiber was dissolved in 50 g of water (distilled water; D.I. water) as a solvent to prepare a silk fiber solution.

0.05 g of the iron acetylacetonate was added to the silk fiber solution and dispersed well.

The ketchen black (0.05 g) was added to the silk fiber solution in which the metal precursor was dispersed.

Then, the silk fiber solution into which the metal precursor and the carbon black were added was stirred to prepare a catalyst precursor. At this time, the stirring was carried out at 70 ° C for 15 minutes so that the metal precursor and the carbon black were adsorbed on the surface of the silk fiber.

The catalyst precursor was placed in an oven and dried at about 100 DEG C for 15 hours.

The dried catalyst precursor was placed in a tube furnace and heat-treated in an argon (Ar) gas atmosphere at a temperature range of about 850 to 950 ° C to finally obtain a catalyst.

This corresponds to a silk fiber-based iron-nitrogen-carbon catalyst, and hereafter the catalyst obtained is designated as Fe / N / C-900 as occasion demands.

(2) Manufacture of metal air cell

For negative electrode formation, about 0.75 g of zinc powder was wetted with about 200 microns of 6 molar KOH aqueous solution.

In order to form a separator, a nylon membrane was laminated on the negative electrode.

Next, a gas diffusion layer was prepared by coating a mixture of active carbon powder and polytetrafluoroethylene (PTFE) at a weight ratio of about 7: 3 in a weight ratio of about 60: 1 with a nickel mesh.

The catalyst powder prepared in (1) of Example 1 was made into ink, the ink was dropped on the gas diffusion layer, vacuum adsorbed on the catalyst dispersion, and dried to prepare an air electrode (anode).

Specifically, about 12 mg of the catalyst powder prepared in (1) of Example 1 was added to a solvent (400 μL of a Nafion solution of about 0.05% by weight and a mixed solution of about 1600 μL of ethanol) And then ultrasonicated for about 1 hour.

Comparative Example  One

A platinum catalyst purchased from Premetek corporation was prepared and a metal air cell including the platinum catalyst was prepared in the same manner as in Example 1.

Comparative Example  2

A catalyst was provided in the same manner as in Example 1 except that the heat treatment temperature was set at 800 캜, and a metal air cell including the catalyst was prepared.

Comparative Example  3

A catalyst was provided in the same manner as in Example 1 except that the heat treatment temperature was set at 1000 캜, and a metal air cell including the catalyst was prepared.

Comparative Example  4

A metal air cell was fabricated in the same manner as in (2) of Example 1 except that a positive electrode to which no catalyst was applied was used.

Experimental Example  1: Property analysis of catalyst

(1) Scanning electron microscope ( SEM ), Transmission electron microscope ( TEM ) And its fast Fourier transform ( FFT ) analysis

A SEM photograph (S-4800m, Hitachi) was taken to observe the surface characteristics of the catalyst according to Example 1 and is shown in Fig.

According to Fig. 1A, it can be seen that the catalyst of Example 1 has iron uniformly distributed on the surface of the carbonized fibril.

Further, the TEM image (HR-TEM, JEOL JEM-2100F) of the catalyst according to Example 1 was photographed and shown in FIGS. 1B and 1C.

The FFT result for FIG. 1B is shown in the lower left of FIG. 1B, and the FFT result for FIG. 1C is shown separately in FIG. 1D.

1b to 1d, it can be confirmed that the catalyst of Example 1 is composed mainly of amorphous carbon, and iron or iron compound bound thereto is present.

(2) X-ray diffraction  analysis ( XRD )

In order to more specifically describe the structural characteristics of the catalyst according to Example 1, XRD analysis was performed using (D / Max 2000, Rigaku). CuK? Light source at 40 kV, and the results are shown in FIGS. 2A and 2B.

Specifically, FIG. 2A shows the results of Comparative Examples 2 and 3 as well as Example 1. FIG. In FIG. 2B, only the results of Example 1 are shown in detail.

For reference, the Y-axis in FIGS. 2A and 2B is an arbitrary scale, meaning no unit, and the position of a relative peak can have a meaning.

According to FIG. 2A, peaks at 26 and 43 ° positions in Example 1, Comparative Examples 2 and 3 are observed, and these catalysts can commonly confirm the presence of amorphous carbon.

Further, in Fig. 2 (b), it is confirmed that chol (Fe) and iron carbide (Fe ₃ C) exist in the catalyst of Example 1.

As a result, it can be seen that the catalyst of Example 1 has amorphous carbon as a main skeleton, and iron (Fe) and iron carbide (Fe ₃ C) bonded thereto exist. Further, it is important to control the final heat treatment temperature range to 850 to 920 ° C in order to form a catalyst including iron (Fe) and iron carbide (Fe ₃ C).

(3) X-ray photoelectron spectroscopy ( XPS )

In order to examine the constituent elements of the catalyst according to Example 1, XPS analysis was performed using a Thermo Scientific K? Spectrometer (Thermo Fisher UK, 1486.6 eV). In addition, XPS analysis was performed on the catalysts of Comparative Examples 2 and 3 as well.

FIG. 3A is a graph showing the results of analysis of iron 2p, oxygen 1s, nitrogen 1s and carbon 1s orbitalspectra spectra with respect to the catalysts according to the temperature. Thus, the kind and relative content of the elements existing in the catalyst can be grasped.

Specifically, it can be seen that the content of iron, oxygen, nitrogen, and carbon in the case of Example 1 is 0.53 wt%, 5.43 wt%, 1.59 wt%, and 92.4 wt%, respectively.

In contrast, in Comparative Example 2, the respective contents were 0.33 wt%, 5.39 wt%, 1.6 wt%, and 92.54 wt%, and in Comparative Example 3, the respective contents were 0.33 wt%, 3.82 wt%, 1.36 wt% , And 94.49 wt%, respectively.

FIG. 3B is a graph showing the 1s orbital spectra of nitrogen with respect to the catalysts, and the kind and the relative ratio of the doped nitrogen in the catalyst can be grasped.

Specifically, the doped nitrogen in the catalyst of Example 1, Comparative Examples 2 and 3 is combined with the carbonized carbon black to form pyridinic, pyrrolic, graphitic, or oxidized ) There are four forms of nitrogen, but their abundance ratios are different.

More specifically, in Example 1, the weight ratio of oxidized nitrogen to pyridinic nitrogen was 1.18, while in Comparative Example 3, the weight ratio was 1.52.

In summary, the catalyst of Example 1 contains iron, oxygen, nitrogen, and carbon, and the content of doped nitrogen is within the range of 1.3 to 1.6 wt%, which results in the formation of pyridinic, It can be seen that the weight ratio of oxidized nitrogen to nitrogen is 1.18. When these results are compared with those of Comparative Examples 2 and 3, it can be understood that it is important to control the final heat treatment temperature range to 850 to 920 占 폚.

FIG. 3c is a graph showing the Fe 2p orbital spectra of the catalysts, and it is possible to grasp the distribution of iron bound to other elements in the catalyst.

Experimental Example  2: Electrochemical characterization of cell

(1) Stability evaluation

The electrochemical characteristics of the catalyst according to Example 1 were analyzed using RRDE (ALS Co., Ltd). In order to prepare this, the same analysis was carried out for Comparative Examples 1 to 4 as well.

Specifically, FIG. 4A shows a linear scanning voltammogram for Example 1 and Comparative Examples 1 to 4 at 0.1 M electrolyte and a scanning rate of 10 mVs ^-1 .

According to FIG. 4A, the battery of Example 1 exhibits excellent starting potential and current, and is comparable in performance to the battery of Comparative Example 1 in particular. The battery of Comparative Example 2 has a starting potential of about 0.05 V negative and a current density of about 0.9 mA cm ^-2 lower than that of Example 1. In addition, the battery of Comparative Example 3 starts from a negative value of about 0.02 V and the current density is also about 0.8 mA cm ^-2 lower than that of Example 1.

As a result, the catalyst of Example 1 is superior to the catalyst of Comparative Examples 2 and 3, and can be evaluated to have a catalyst performance equivalent to that of platinum (Comparative Example 1).

4B shows the ratio of hydrogen peroxide generation for Example 1 and Comparative Examples 1 to 4 under the conditions of a 0.1 M electrolytic solution and a scanning speed of 10 mVs < ^-1 >.

According to FIG. 4B, the four-electron reaction is superior to the two-electron reaction during the oxygen reduction reaction, and thus the rate of occurrence of peroxide is low. The catalyst of Comparative Example 1 has a relatively large amount of two- There is a high rate of occurrence. The catalyst of Comparative Example 2 exhibited a lower rate of generation of peroxide than that of Comparative Example 1 and exhibited a value similar to that of Example 1. The battery of Comparative Example 3 also exhibited characteristics similar to those of Comparative Example 2.

Accordingly, it can be understood that the catalyst of Example 1 can improve the efficiency of the oxygen reduction reaction.

Fig. 4C shows the results of cyclic voltammetry analysis for Example 1 at a scan rate of 50 mVs < ^{-1 &} gt ;.

According to FIG. 4C, it is confirmed that there is almost no difference between the first cycle and the 1000th cycle, whereby the stability of the catalyst manufactured in Embodiment 1 can be grasped.

4D shows the methanol tolerance test results for Example 1 and Comparative Example 1 at 0.1 M electrolyte and scanning speed of 10 mVs ^-1 .

According to Fig. 4d, the catalyst of Example 1 appears to have no reactivity with methanol, and is believed to exhibit stable electrochemical performance when methanol is used as a solvent.

On the other hand, the catalyst of Comparative Example 1 appears to have reactivity with methanol, and it is deduced that when methanol solvent is used, it exhibits unstable electrochemical performance.

Thus, unlike platinum (Comparative Example 1), the catalyst of Example 1 is not reactive with methanol and can be evaluated as contributing to the electrochemical stability of the battery.

4A to 4D, it can be understood that the catalyst of Example 1 is a catalyst having excellent electrochemical characteristics and stability.

(2) Evaluation of output characteristics

5A is a graph showing output densities according to current densities of zinc air cells of Example 1 and Comparative Examples 1 and 3.

Comparing the graphs shown in FIG. 5A, it can be seen that the performance of the cathode (anode) of the cell of Example 1 is the most excellent.

5B and 5C are graphs showing discharge characteristics of zinc air cells of Example 1 and Comparative Example 1, respectively. Specifically, the discharge current in FIG. 5B is 50 mA / cm ² , and the discharge current in FIG. 5C is 25 mA / cm ² .

Referring to FIGS. 5B and 5C, it can be seen that the performance of the air electrode (anode) of the cell of Example 1 is the best at various discharge current densities.

In summary, it can be seen that the catalyst of Example 1 is a catalyst capable of improving the electrochemical performance of an air electrode (anode) in a zinc air cell.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. As will be understood by those skilled in the art. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (29)

delete delete delete delete delete delete delete delete Dissolving the silk fibers in a solvent to produce a silk fiber solution;
Introducing a metal precursor and carbon black into the silk fiber solution;
Stirring the silk fiber solution charged with the metal precursor and the carbon black to prepare a catalyst precursor; And
And heat treating the catalyst precursor to obtain a catalyst.
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
Heat treating the catalyst precursor to obtain a catalyst,
The heat-
Lt; RTI ID = 0.0 > 850 < / RTI >
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
Heat treating the catalyst precursor to obtain a catalyst,
The heat-
RTI ID = 0.0 > 1 < / RTI >
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
Heat treating the catalyst precursor to obtain a catalyst,
The heat-
Wherein the reaction is carried out in an inert gas atmosphere.
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
Stirring the silk fiber solution charged with the metal precursor and the carbon black to prepare a catalyst precursor,
Wherein the metal contained in the metal precursor and the carbon black are adsorbed on the surface of the silk fiber.
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
Stirring the silk fiber solution charged with the metal precursor and the carbon black to prepare a catalyst precursor,
Is carried out at a stirring rate of 100 to 500 rpm.
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
Stirring the silk fiber solution charged with the metal precursor and the carbon black to prepare a catalyst precursor,
RTI ID = 0.0 > 5-15 < / RTI > minutes,
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
Dissolving the silk fibers in a solvent to produce a silk fiber solution,
The content of silk fibers in the silk fiber solution is,
By weight of said silk fibers, based on the total weight of said silk fiber solution, expressed as 0.99% to 1.48%
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
Dissolving the silk fibers in a solvent to produce a silk fiber solution,
The silk fibers are nitrogen-doped,
The content of the doped nitrogen in the silk fibers is,
Wherein the weight percentage of the doped nitrogen to the silk fibers is 0.01 to 0.02 wt%
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
Introducing a metal precursor and carbon black into the silk fiber solution,
Introducing and dispersing the metal precursor into the silk fiber solution; And
And injecting the carbon black into a silk fiber solution in which the metal precursor is dispersed.
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
19. The method of claim 18,
In the step of injecting and dispersing the metal precursor into the silk fiber solution,
The amount of the metal precursor to be charged is,
Wherein the weight ratio of the metal precursor to the silk fibers in the silk fiber solution is 6.67: 100 to 15: 100.
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
19. The method of claim 18,
Adding carbon black to a silk fiber solution in which the metal precursor is dispersed, and stirring the carbon fiber,
The amount of the carbon black to be added is,
Wherein the weight ratio of the carbon black to the silk fiber in the silk fiber solution is 6.67: 100 to 15: 100.
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
Stirring the silk fiber solution charged with the metal precursor and the carbon black to prepare a catalyst precursor; Since the,
And drying the catalyst precursor.
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
22. The method of claim 21,
The drying is carried out,
Lt; RTI ID = 0.0 > 90-100 C. < / RTI >
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
22. The method of claim 21,
The drying is carried out,
RTI ID = 0.0 > 12-24 < / RTI > hours,
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
The metal precursor,
At least one selected from the group consisting of metal acetylacetonate, metal acetate, and combinations thereof.
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
The metal constituting the metal precursor may be,
At least one selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), and combinations thereof.
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
The carbon black may be,
Ketjen black. ≪ RTI ID = 0.0 >
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
10. The method of claim 9,
The solvent may be,
Wherein the solvent is at least one selected from the group consisting of water, ethanol, acetone, and combinations thereof.
METHOD FOR PRODUCING COMPOSITE CATALYST FOR METAL AIR BATTERY
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