KR20160031184A - Cathod catalyst for ait battery and method of manufacturing the same - Google Patents

Abstract

Disclosed is a positive electrode catalyst for an air battery. According to an embodiment of the present invention, the positive electrode catalyst for an air battery may include a Perovskite structure compound represented by chemical formula 1. In the chemical formula 1, X represents one or more elements from lanthanoid elements; Y represents one or more elements from alkali earth metal elements; Z represents one or more elements from iron family elements; and O represents oxygen. According to the present invention, the positive electrode catalyst for an air battery which can perform both oxygen reduction and oxygen generation can be provided. Also, the surface area of a cathode where the oxygen reduction and oxygen generation can be performed is increased, and thereby the oxygen reduction and oxygen generation can be performed more efficiently.

Description

TECHNICAL FIELD [0001] The present invention relates to a cathode catalyst for an air metal battery,

A cathode catalyst for air cells, and a process for producing the same.

A metal air cell is a cell that uses oxygen in the air as an energy source and generates electrical energy by reducing oxygen. Compared to conventional primary batteries and lithium secondary batteries, which are typical secondary batteries, they have a high energy density and high output power.

In the case of metal air cells, the cathode is divided into an anode, which is a cathode for oxygen reduction, and a cathode, which oxidizes the metal, and a separator for separating the electrolyte and an electrolyte for supporting the movement of ions. In order to improve the overall efficiency of the metal air cell, oxygen must be efficiently reduced at the anode when discharging and oxygen must be efficiently generated at the anode when charging.

At this time, a method of adsorbing a catalyst on a cathode, which is an anode, to make two layers of poles to reduce and oxidize oxygen is used. In the reduction of oxygen during discharging, electrons are generated as the metal is oxidized at the cathode, 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.

Scheme 1 (reduction of oxygen: discharge)

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

Scheme 2 (oxidation of oxygen: charge)

Anode reaction: 4OH ^- ? O ₂ + 2H ₂ O + 4e ^-

When only a carbon cathode is used without using a catalyst, the anodic reaction is not efficiently performed and the characteristics of the coral reduction reaction are not good. Therefore, it is necessary to develop a new catalyst because it is disadvantageous in terms of cost and electrolyte is not an alkaline solution but shows poor characteristics in a solution such as methanol.

The present invention relates to a positive electrode catalyst for air metal batteries and a method for producing the same.

The anode catalyst for an air cell according to an embodiment of the present invention may include a perovskite structure compound represented by the following formula (1).

[Chemical Formula 1]

_{(X p X '(1-} p)) α (Y q Y' (1-q)) (1-α) (Z r Z '(1-r)) O (3-δ)

(Wherein X and X 'independently represent at least one element of the lanthanum element, Y and Y' independently represent at least one element of the alkaline earth metal element, and Z and Z 'represent at least one element , And O means oxygen.)

The alpha value may be 0.1 to 0.5. Or may be 0.2 to 0.4.

The p, q, or r may be greater than 0 and less than or equal to 1.

X may be lanthanum (La) (in which case the value of p is 1).

The Y _q Y ' _(1-q) may be represented by the following formula (2).

(2)

Ba _q Sr _(1-q)

The q may be 0.3 to 0.7. Alternatively, q may be 0.4 to 0.6.

The Z _r Z ' _(1-r) can be represented by the following formula (3).

(3)

Co _y Fe _(1-y)

The? Value may be 0.6 to 1.0. Alternatively, the value of? May be 0.7 to 0.9.

The? May be 0 to 1. Alternatively, the delta may be 0.2 to 0.8.

The particle size of the perovskite structure compound may be 0.2 탆 to 3.2 탆.

The surface of the perovskite structure compound may have a rhombohedral structure compound represented by the following formula (4).

[Chemical Formula 4]

XZO _(3-epsilon)

(Where X is at least one element of the lanthanum element, Y is at least one element of the alkaline earth metal element, Z is at least one element of the iron family element, and O is oxygen.)

The epsilon may be 0 to 0.4.

[Formula 4] may be LaCoO _(3-epsilon) .

The particle size of the compound of the rhombohedral structure may be 0.8 nm to 1.2 nm.

In order to produce the positive electrode catalyst for air cells, the following catalyst preparation method may be provided.

In one embodiment, a method for producing a cathode catalyst for an air cell comprises the steps of adding a nitrate compound of a lanthanum element, a nitric acid compound of an alkaline earth metal element, a nitric acid compound of an iron family element, and a carboxylic acid to a buffer solution containing ammonia to prepare a precursor solution ; Stirring the precursor solution and subjecting it to a first heat treatment to produce a precursor; And a second heat treatment after pulverizing the precursor.

Wherein the nitrate compound of the lanthanum element is lanthanum nitrate, the nitrate compound of the alkaline earth metal element is barium nitrate, strontium nitrate, or a combination thereof, and the nitrate compound of the iron family element is cobalt nitrate, iron nitrate, .

The molar ratio of the lanthanum nitrate: barium nitrate: strontium nitrate: cobalt nitrate: iron nitrate may be 0.4 to 0.8: 0.5 to 0.9: 0.5 to 0.9: 1.4 to 1.8: 0.2 to 0.6.

The amount of the added lanthanum nitrate may be 19 to 23 wt% based on the weight of the added lanthanum nitrate, barium nitrate, strontium nitrate, cobalt nitrate, and iron nitrate.

The buffer solution containing ammonia may be prepared by mixing an ammonium hydroxide solution and ethylenediaminetetraacetic acid in an amount of 0.9 to 1.1 mol based on the molar amount of the ammonium hydroxide.

The carboxylic acid may be citric acid.

The citric acid may be added in an amount of 1.3 to 1.7 mol based on the molar amount of ammonium hydroxide.

The pH of the precursor solution may be from 7 to 8.

The stirring may be carried out at 80 to 120 캜 for 20 to 28 hours.

The primary heat treatment may be performed at 180 캜 to 240 캜 for 4 hours to 8 hours.

The second heat treatment may be performed at 1050 캜 to 1150 캜 for 3 hours to 7 hours.

And a step of grinding after the secondary heat treatment step.

According to an embodiment of the present invention, it is possible to provide a positive electrode catalyst for bi-functional air metal cells capable of both oxygen reduction and oxygen generation.

Also, by increasing the surface area at which oxygen reduction reaction and formation reaction can occur in the air electrode, oxygen reduction reaction and production reaction can be performed more efficiently.

1 is an SEM photograph of a cathode catalyst for an air cell manufactured according to an embodiment.
FIG. 2 is a SEM photograph (a) of Ba _{0 .5} Sr _{0 .5} Co _{0 .8} Fe _{0 .2} O used as a conventional positive electrode catalyst and an SEM photograph (b) of a positive electrode catalyst according to an embodiment.
FIG. 3 is a linear scanning voltammogram graph measuring the ORR performance of the anode catalysts according to Examples and Comparative Examples. FIG.
FIG. 4 is a graph of a linear injection voltammetry measuring the OER performance of a cathode catalyst for Examples and Comparative Examples. FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims. Like reference numerals refer to like elements throughout the specification.

Thus, in some embodiments, well-known techniques are not specifically described to avoid an undesirable interpretation of the present invention. Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Whenever a component is referred to as "including" an element throughout the specification, it is to be understood that the element may include other elements, not the exclusion of any other element, unless the context clearly dictates otherwise. Also, singular forms include plural forms unless the context clearly dictates otherwise.

The anode catalyst for an air cell according to an embodiment of the present invention may include a perovskite structure compound expressed by the following formula (1).

[Chemical Formula 1]

_{(X p X '(1-} p)) α (Y q Y' (1-q)) (1-α) (Z r Z '(1-r)) O (3-δ)

(Wherein X and X 'independently represent at least one element of the lanthanum element, Y and Y' independently represent at least one element of the alkaline earth metal element, and Z and Z 'represent at least one element , And O means oxygen)

The? May be 0 to 1. Alternatively, the delta may be 0.2 to 0.8.

That is, when X, X ', Y or Y' form a simple cubic lattice, oxygen (O) exists in the center of the simple cubic lattice, and Z Or Z ' is present.

The alpha value may be 0.1 to 0.5. Or may be 0.2 to 0.4.

The p, q, or r may be greater than 0 and less than or equal to 1. Here, when the value of p, q, or r is 1, it means that a single element is not a heterogeneous element.

X may be lanthanum (La).

The Y _q Y ' _(1-q) may be represented by the following formula (2).

(2)

Ba _q Sr _(1-q)

The q may be 0.3 to 0.7. Alternatively, q may be 0.4 to 0.6.

The Z may be represented by the following formula (3).

(3)

Co _r Fe _(1-r)

The r may be 0.6 to 1.0. Alternatively, the value of? May be 0.7 to 0.9.

The particle size of the perovskite structure compound may be 0.2 탆 to 3.2 탆.

The surface of the perovskite structure compound may have a rhombohedral structure compound represented by the following formula (4).

[Chemical Formula 4]

XZO _(3-epsilon)

(Where X is at least one element of the lanthanum element, Y is at least one element of the alkaline earth metal element, Z is at least one element of the iron family element, and O is oxygen.

The epsilon may be 0 to 0.4.

[Formula 4] may be LaCoO _(3-epsilon) .

The particle size of the compound of the rhombohedral structure may be 0.8 nm to 1.2 nm.

In order to produce the positive electrode catalyst for air cells, a catalyst preparation method according to the following embodiments can be provided.

[Example 1]

1 M ammonium hydroxide (NH ₄ OH) was mixed with ethylenediamine tetraacetic acid in the same molar amount as ammonium hydroxide to make a buffer solution.

Thereafter, lanthanum nitrate hexahydrate (La (NO ₃ ) ₃ .6H ₂ O): barium nitrate (Ba (NO ₃ ) ₂ ): strontium nitrate (Sr (NO ₃ ) ₂ ): cobalt nitrate hexahydrate ₃ ) ₂ .6H ₂ O): Iron nitrate (Fe (NO ₃ ) ₃ .9H ₂ O) was added to the buffer solution at a ratio of 0.6 mol: 0.7 mol: 0.7 mol: 1.6 mol: 0.4 mol.

The amount of lanthanum nitrate hexahydrate (La (NO ₃ ) ₃ .H ₂ O) was 21.31 wt% based on the weight of the added lanthanum nitrate, barium nitrate, strontium nitrate, cobalt nitrate and iron nitrate.

In addition, citric acid corresponding to 1.5 times the molar amount of ammonium hydroxide was added to the buffer solution.

Thereafter, the pH of the solution was adjusted to 8, and the solution was gelated with stirring at 100 DEG C for 24 hours.

The gelated solution was heat treated in an oven at 200 < 0 > C for 6 hours to produce a precursor.

After the heat-treated precursor was pulverized in a mortar for 30 minutes, the pulverized precursor was heat-treated at 1100 ° C for 5 hours. After the heat treatment was completed, the mixture was pulverized in a mortar for 30 minutes.

[Experimental Example 1]

1 is an SEM photograph of a cathode catalyst for an air cell manufactured according to an embodiment.

Referring to FIG. 1, the prepared positive electrode catalyst has a compound of rhombohedral structure deposited on the surface of the perovskite structure compound.

The formula of the perovskite structure compound is expressed as follows.

_{La 0 .3 (Ba 0 .5 Sr} 0 .5) 0.7 Co 0 .8 Fe 0 .2 O (2.7)

The chemical formula of the compound of the rhombohedral structure is expressed as follows.

LaCoO ₃

FIG. 2 is a SEM photograph (a) of Ba _{0 .5} Sr _{0 .5} Co _{0 .8} Fe _{0 .2} O used as a conventional positive electrode catalyst and an SEM photograph (b) of a positive electrode catalyst according to an embodiment.

Referring to FIG. 2, the perovskite structure compound has a particle size of 0.2 to 3.2 μm, and the compound of the rhombohedral structure has a particle diameter of 0.8 to 1.2 nm.

In the case of Ba _{0 .5} Sr _{0 .5} Co _{0 .8} Fe _{0 .2} O (hereinafter referred to as BSCF 5582) conventionally used as an anode catalyst, the average particle diameter is from 4.1 탆 to 16.7 탆. That is, since the average particle diameter is smaller than that of the conventional anode catalyst, the surface area where the reduction and formation reaction of oxygen can occur increases more effectively and oxygen reduction reaction and production reaction can occur more efficiently.

Further, the surface area is further increased by the compound of the rhombohedral structure precipitated and distributed in the compound on the surface of the perovskite structure compound.

[Experimental Example 2]

The oxygen reduction reaction (ORR) performance of the catalyst was measured by mixing 20 wt% of ketjenblack with 80 wt% of the anode catalyst according to Example 1.

In Comparative Example 1, 80 wt% of BSCF5582 and 20 wt% of ketjenblack were used as Comparative Example 2, and RuO ₂ A mixture of 80 wt% and ketjenblack 20 wt% was used as Comparative Example 3, and a mixture of 20 wt% of Pt and Vulcan XC-72 carbon black (VCB) (hereinafter referred to as Pt / C 20%) was used.

FIG. 3 is a linear scanning voltammogram graph measuring the ORR performance of the anode catalysts according to Examples and Comparative Examples. FIG.

(0.1 M KOH electrolyte, scanning speed: 10 mVs < ^-1 >). In the linear scanning voltage method, the electrode was rotated at 1600 rpm on a rotating ring disk electrode (RRDE) and the scanning speed was increased to 10 mVs ^-1 with a potentiostat.

3 (a) is a disk current (i _d), 3 (b) is a hydroperoxide production, Fig. 3 (c) is a ring current (i _r), FIG. 3 (d) is an electron transfer coefficient (electron transfer number.

3, the disc current i _d was improved by about 20% when compared with the comparative example 1 and the comparative example 4, and the ring current i _r ) characteristics are good.

In addition, the amount of hydroperoxide formation (HO ₂ ^- %) was significantly lower than that of Comparative Example 1, and the electron transfer coefficient was superior to that of Comparative Example 1.

[Experimental Example 3]

The oxygen evolution reaction (OER) performance of the catalyst was measured by mixing 20 wt% ketjenblack with 80 wt% of the anode catalyst according to Example 1.

As Comparative Example 1, a mixture of 80 wt% of BSCF5582 and 20 wt% of ketjenblack was used, and a mixture of IrO ₂ A mixture of 80 wt% and ketjenblack 20 wt% was used.

FIG. 4 is a graph of a linear injection voltammetry measuring the OER performance of a cathode catalyst for Examples and Comparative Examples. FIG.

Referring to FIG. 4, it can be seen that the OER performance of the catalyst according to the embodiment is excellent.

Hereinafter, the present invention will be described in detail with reference to Examples. The following examples are illustrative of the present invention only and are not intended to limit the scope of the present invention.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

Claims (20)

A positive electrode catalyst for an air cell, comprising a perovskite structure compound represented by the following formula (1).
[Chemical Formula 1]
_{(X p X '(1-} p)) α (Y q Y' (1-q)) (1-α) (Z r Z '(1-r)) O (3-δ)
(Wherein X and X 'independently represent at least one element of the lanthanum element, Y and Y' independently represent at least one element of the alkaline earth metal element, and Z and Z 'represent at least one element , Where O means 0.1 to 0.5, and p, q, or r is more than 0 and 1 or less.
The method according to claim 1,
And X is lanthanum (La).
3. The method of claim 2,
Y is represented by the following formula (2), and Z is represented by the following formula (3).

(2)
Ba _? Sr _(1-?)

(3)
Co _y Fe _(1-y)

(Where beta is from 0.3 to 0.7 and y is from 0.6 to 1.0)
The method of claim 3,
Wherein the perovskite structure compound has a particle diameter of 0.2 to 3.2 占 퐉.
5. The method according to any one of claims 1 to 4,
Wherein the surface of the perovskite structure compound has a rhombohedral structure compound represented by Formula 4 below.

[Chemical Formula 4]
XZO _(3-epsilon)
(Where X is at least one element of the lanthanum element, Y is at least one element of the alkaline earth metal element, Z is at least one element of the iron family element, and O is oxygen.
5. The method of claim 4,
(4) is LaCoO _(3-epsilon) .
6. The method of claim 5,
Wherein the compound of the rhombohedral structure has a particle diameter of 0.8 nm to 1.2 nm.
Adding a nitrate compound of a lanthanum element, a nitrate compound of an alkaline earth metal element, a nitrate compound of an iron family element, and a carboxylic acid to a buffer solution containing ammonia to prepare a precursor solution;
Stirring the precursor solution and subjecting it to a first heat treatment to produce a precursor; And
And crushing the precursor and subjecting the precursor to a secondary heat treatment.
9. The method of claim 8,
Wherein the nitrate compound of the lanthanum element is lanthanum nitrate.
9. The method of claim 8,
Wherein the nitric acid compound of the alkaline earth metal element is barium nitrate, strontium nitrate, or a combination thereof.
10. The method of claim 9,
Wherein the nitric acid compound of the iron family element is cobalt nitrate, iron nitrate, or a combination thereof.
11. The method of claim 10,
The molar ratio of the lanthanum nitrate: barium nitrate: strontium nitrate: cobalt nitrate:
0.4 to 0.8: 0.5 to 0.9: 0.5 to 0.9: 1.4 to 1.8: 0.2 to 0.6.
11. The method of claim 10,
The amount of the lanthanum nitrate to be added is,
Wherein the weight ratio of lanthanum nitrate, barium nitrate, strontium nitrate, cobalt nitrate, and iron nitrate is 19 to 23 wt% based on the weight of the lanthanum nitrate, barium nitrate, strontium nitrate, cobalt nitrate and iron nitrate.
11. The method of claim 10,
The buffer solution containing ammonia,
Ammonium hydroxide solution and ethylenediaminetetraacetic acid in an amount of 0.9 to 1.1 mol based on the molar amount of the ammonium hydroxide.
12. The method of claim 11,
Wherein the carboxylic acid is citric acid.
13. The method of claim 12,
Wherein the citric acid is added in an amount of 1.3 to 1.7 mol based on the molar amount of ammonium hydroxide.
14. The method of claim 13,
Wherein the precursor solution has a pH of from 7 to 8.
15. The method of claim 14,
Wherein the stirring is performed at 80 to 120 DEG C for 20 to 28 hours.
19. The method of claim 18,
Wherein the first heat treatment step comprises:
At 180 占 폚 to 240 占 폚 for 4 hours to 8 hours.
20. The method of claim 19,
Wherein the second heat treatment step comprises:
Wherein said step (c) is carried out at 1050 캜 to 1150 캜 for 3 hours to 5 hours.

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