KR101370939B1 - Zirconium-doped cerium oxide, method for producing the same and air electrode for metal-air secondary battery including the same as catalyst - Google Patents

Abstract

The present invention relates to a metal-air secondary battery, and more particularly, a zirconium-doped cerium oxide of a new composition having improved catalytic activity to be used as an activation catalyst in a metal-air secondary battery, a method of manufacturing the oxide, and the oxide It relates to an air electrode for a metal air secondary battery comprising a catalyst and a metal air secondary battery comprising the air electrode.

Description

Zirconium-doped cerium oxide, a method of manufacturing the same, and an air electrode for a metal air secondary battery comprising the oxide as a catalyst AS CATALYST}

The present invention relates to a metal-air secondary battery, and more particularly, a zirconium-doped cerium oxide of a new composition having improved catalytic activity to be used as an activation catalyst in a metal-air secondary battery, a method of manufacturing the oxide, and the oxide It relates to an air electrode for a metal air secondary battery comprising a catalyst and a metal air secondary battery comprising the air electrode.

Increasing interest in the environment has strengthened regulations on environmental pollutants. Among them, lead-acid batteries or Ni-Cd secondary batteries using heavy metals as electrode active materials have a harmful effect on the human body, and therefore, some countries regulate their use by law. For this reason, there has been increased interest in Ni-MH batteries, in which the heavy metal Cd has been replaced with metal hydrides, and lithium ion secondary batteries, which exhibit high operating voltages and high energy densities per mass in Ni-Cd cells.

Li-ion secondary batteries have been widely used as power sources for portable devices since they emerged in 1991 as small, light and large capacity batteries. Recently, with the rapid development of electronics, telecommunications, and computer industry, camcorders, mobile phones, notebook PCs, etc. have emerged and are developing remarkably, and the demand for lithium ion secondary battery as a power source to drive these portable electronic information communication devices is increasing day by day. It is increasing.

Although such lithium ion battery cells are attracting much attention as eco-friendly electric vehicle batteries, they have problems such as high price of cathode active material and low energy density. Various active materials have been studied to solve this problem.

The metal-air battery is a battery in which the cathode active material of the lithium ion secondary battery is replaced with air. The energy density of the metal-air battery is ten times higher than that of the lithium ion secondary battery using a conventional cathode active material. So that the weight of the positive electrode and the entire cell can be remarkably reduced.

In particular, theoretically, oxygen is enriched in air in a Li-air electrochemical pair and Li is an attractive material because it has a higher capacity than weight. Rechargeable Li-air cells have about three times higher energy density than conventional Li-ion cells, but Li-related oxygen reduction reaction (ORR) and oxygen generation reaction ( OER) is only known. In addition, the reaction of Li and oxygen to form lithium oxide is much more complicated and it is necessary to overcome many disadvantages for commercialization of Li-air battery. These disadvantages are the voltage difference, repetition, capacity and lifetime .

In order to put the metal-air battery into practical use, it is necessary to have safety in a receiving system and a non-aqueous electrolyte, a wide operating temperature, high output characteristics, and low cost. In order to achieve this, it is necessary to develop a solid electrolyte having a high ion conductivity and to study and develop a catalyst for improving the performance of the oxygen electrode. In particular, it is important to find a suitable electrochemical catalyst capable of breaking the strong bond between oxygen and oxygen.

Although a few air electrode catalysts have recently been introduced, extensive research into metal air cells has not yet been conducted, and studies showing reversibility within limited charge / discharge cycles have not been reported.

As a result of efforts to solve the problems of the prior art, the inventors of the present invention have completed the present invention by developing a catalyst of a new composition which can further improve the catalytic activity so that it can be used as an activation catalyst in a metal-air secondary battery.

Accordingly, it is an object of the present invention to provide a zirconium-doped cerium oxide of a novel composition which can be used as a catalyst in oxygen reduction, activating materials and metal air secondary batteries.

Another object of the present invention is to provide a zirconium-doped cerium oxide manufacturing method that can be easily produced by the combustion method of the zirconium-doped cerium oxide of the novel composition.

It is still another object of the present invention to provide a metal air secondary battery air electrode having a significantly high discharge capacity by including a zirconium-doped cerium oxide as a catalyst and a metal air secondary battery including the air electrode.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to achieve the above object of the present invention, the present invention provides a zirconium-doped cerium oxide represented by the formula (1).

[Chemical Formula 1]

Ce _1-x Zr _x O ₂ (0.1≤x≤0.5)

In a preferred embodiment, the oxide has hexagonal fluorite crystal structure.

In a preferred embodiment, the particle size of the oxide is 5-20 nm.

In addition, the present invention is a zirconium-doped cerium oxide manufacturing method, a reaction solution preparation step of preparing a reaction solution by mixing cerium nitrate, zircon nitrate, water and flammable liquid; A combustion step of combusting the reaction solution; It provides a zirconium-doped cerium oxide manufacturing method comprising a; and a recovery step of recovering the particles remaining after the combustion step.

In a preferred embodiment, zirconium and cerium dissolved in the reaction solution has a molar ratio of 1: 1 to 1: 9.

In a preferred embodiment, the concentration ratio of cerium nitrate, zircon nitrate and flammable liquid in the reaction solution is determined by the following formula (1).

[Equation 1]

Concentration ratio = C _c + C _z / C _f

C _c : absolute value of valence of cerium nitride x molar ratio of cerium

C _z : absolute value of valence of zircon nitrate x molar ratio of zirconium

C _f : absolute value of valence of flammable liquid

In a preferred embodiment, the combustion step is carried out by completely burning the reaction solution at a temperature of 250 to 350 ° C.

In a preferred embodiment, the flammable liquid is Glycine [C ₂ H ₅ O ₂ N], Urea [CO (NH ₂ ) ₂ ], Citric acid [C ₆ H ₈ O ₇ ], Sucrose [C ₁₂ H ₂₂ O ₁₁ ], Ammonium nitrate [NH ₄ NO ₃ ], Polyvinyl alcohol [(C ₂ H ₄ O) n], Hexamine [C ₆ H ₁₂ N ₄ ], Oxalyl dihydrazide [ODH: C ₂ H ₆ O ₂ N ₄ ], Malonic acid dihydrazide [MDH: C ₃ H ₈ N ₄ O ₂ ] One or more selected from the group consisting of.

In a preferred embodiment, the size of the remaining particles recovered in the recovery step is 5-20 nm.

The present invention also provides an air electrode for a metal-air secondary battery comprising the above-described zirconium-doped cerium oxide as a catalyst.

In a preferred embodiment, the metal is selected from the group consisting of Zn, Al, Mg, Fe, and Li.

In a preferred embodiment, the air electrode includes carbon: zirconium-doped cerium oxide: binder in a weight ratio of 75 to 85: 5 to 20: balance.

The present invention also provides a metal air secondary battery comprising the air electrode described above.

In a preferred embodiment, the secondary electrode is Li and the non-aqueous electrolyte.

The present invention has the following excellent effects.

First, the zirconium-doped cerium oxide of the present invention has a novel composition that can be used as a catalyst in the reduction of oxygen, the activating material and the metal-air secondary battery.

In addition, the zirconium-doped cerium oxide manufacturing method of the present invention can simply produce a zirconium-doped cerium oxide of a novel composition using a combustion method.

In addition, the air electrode for the metal-air secondary battery of the present invention and the metal-air secondary battery including the air electrode have a significantly higher discharge capacity characteristics by including a zirconium-doped cerium oxide as a catalyst, so the energy density is higher than that of the prior art. The battery can be provided, contributing to the commercialization of electric vehicles.

1 is an XRD pot graph of a zirconium-doped cerium oxide prepared according to one embodiment of the present invention.
2 is SEM images of zirconium-doped cerium oxide prepared according to one embodiment of the present invention.
FIG. 3 is TEM images of zirconium-doped cerium oxide prepared according to one embodiment of the present invention and selected area diffraction (SAD) images of zirconium-doped cerium oxide (Z2) obtained in Example 2. FIG.
FIG. 4 is an XPS spectra of zirconium-doped cerium oxide prepared according to one embodiment of the present invention, which is an XPS spectra of Ce 3d, O 1s and Zr 3d, respectively.
5 is a graph illustrating a BET surface area measurement result of a zirconium-doped cerium oxide prepared according to one embodiment of the present invention.
6 is a schematic view of a metal-air secondary battery manufactured according to another embodiment of the present invention.
(A) of FIG. 7 shows an electrochemical impedance spectra (b) of metal air secondary batteries prepared according to other embodiments including zirconium-doped cerium oxide prepared according to one embodiment of the present invention. Equivalent circuit diagram using data formatted according to the measurement of).
8 is a Cyclic voltammogram (Scan rate) of a metal air secondary cell (Li / O2 coin cell) prepared according to another embodiment including a zirconium-doped cerium oxide catalyst prepared according to one embodiment of the present invention 0.5 mV / s) graph.
FIG. 9 is a 60 mA / g current of a metal air secondary cell (Li / O2 coin cell) prepared according to another embodiment including a zirconium-doped cerium oxide catalyst prepared according to one embodiment of the present invention. A graph showing the discharge performance when is applied.

Although the terms used in the present invention have been selected as general terms that are widely used at present, there are some terms selected arbitrarily by the applicant in a specific case. In this case, the meaning described or used in the detailed description part of the invention The meaning must be grasped.

Hereinafter, the technical structure of the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals used to describe the present invention throughout the specification denote like elements.

First, the first technical feature of the present invention is to develop a cerium oxide doped with zirconium with a new composition as a novel catalyst material capable of easily reducing oxygen.

That is, cerium dioxide, commonly known as cerium oxide, is very attractive because of its ability to store and dissipate oxygen in the application of catalysts, and thus has attracted attention as a catalyst for surrounding oxidation such as a liquid oxidation catalyst or an oxidation-reduction catalyst for organic pollutants. If it is possible to easily catalyze the reduction of oxygen, it can be applied as a variety of catalysts in many places as a new activation catalyst.

The zirconium-doped cerium oxide of the present invention having these characteristics is represented by the following formula (1).

[Chemical Formula 1]

Ce _1-x Zr _x O ₂ (0.1≤x≤0.5)

The zirconium-doped cerium oxide represented by Chemical Formula 1 has hexagonal fluorite structure crystals, and the particle size is in the range of 5-20 nm.

Next, a second technical feature of the present invention lies in a method for producing a zirconium-doped cerium oxide of Chemical Formula 1 using a combustion method.

Therefore, the zirconium-doped cerium oxide manufacturing method of the present invention comprises a reaction solution preparation step of preparing a reaction solution by mixing cerium nitrate, zircon nitrate, water and flammable liquid; A combustion step of combusting the reaction solution; And a recovery step of recovering the particles remaining after the combustion step.

Here, the water contained in the reaction solution is preferably deionized water or distilled water treated so as not to affect the valence, and zirconium and cerium dissolved in the reaction solution preferably have a molar ratio of 1: 1 to 1: 9.

In addition, the concentration ratio of cerium nitrate, zircon nitrate and the flammable liquid in the reaction solution may be determined by Equation 1 below.

[Equation 1]

Concentration ratio = C _c + C _z / C _f

C _c : absolute value of valence of cerium nitride x molar ratio of cerium

C _z : (absolute valence of zircon nitrate x molar ratio of zirconium

C _f : absolute value of valence of flammable liquid

An example of determining the concentration ratio through Equation 1 will be described as a case where the flammable liquid is Glycine.

The valence of the substance dissolved in the reaction solution is H ⁺ → 1, C ⁺⁴ → 4, N ^-3 → 0, O ^-2 → -2, Ce ⁺⁴ → 4, Zr ⁺⁴ → 4.

The valence of cerium nitrate is Ce (NO ₃ ) ₃ → Ce ⁺⁴ +3 (N ^-3 +3 [O ^-2 ]) = -14, and the valence of zircolyl nitrate is ZrO (NO ₃ ) ₂ → Zr ⁺⁴ + (O ^-2 ) +2 (N ^-3 +3 [O ^-2 ]) =-10, and the valence of glycine is C ₂ H ₅ O ₂ N → 2 [H ⁺ ] + [N ^-3 ] + [C ⁺⁴ ] + 2 [H ⁺¹ ] + [C ⁺⁴ ] + [O ^-2 ] + [O ^-2 ] + [H ⁺ ] = 9.

When cerium is 0.9 mol and zirconium is 0.1 mol, the concentration ratio = [(14 × 0.9) + (10 × 0.1)] / 9, so the concentration ratio of cerium nitrate and zircon nitrate and flammable liquid is calculated to be about 1.51. Therefore, a flammable liquid can be added to the reaction solution according to the concentration ratio.

In addition, the combustion step is performed by completely burning the reaction solution containing the flammable liquid at a temperature of 250 to 350 ℃ through the flammable liquid. At this time, the combustible liquid may be used as all materials that can be used as fuel, Glycine [C ₂ H ₅ O ₂ N], Urea [CO (NH ₂ ) ₂ ], Citric acid [C ₆ H ₈ O ₇ ], Sucrose [C ₁₂ H ₂₂ O ₁₁ ], Ammonium nitrate [NH ₄ NO ₃ ], Polyvinyl alcohol [(C ₂ H ₄ O) n], Hexamine [C ₆ H ₁₂ N ₄ ], Oxalyl dihydrazide [ODH: C ₂ H ₆ O ₂ N ₄ ], Malonic acid dihydrazide [MDH: C ₃ H ₈ N ₄ O ₂ ] It is preferably at least one selected from the group consisting of.

The remaining particles obtained after the combustion step as described above are doped cerium oxide doped with zirconium having a formula of 5-20 nm. According to the production method of the present invention, the nano-sized zirconium is doped simply by recovering without further treatment. Obtained cerium oxide can be obtained.

Finally, the third technical feature of the present invention is to provide a metal air secondary battery having excellent discharge capacity characteristics by using a zirconium-doped cerium oxide as a catalyst of the air electrode for the metal air secondary battery.

Accordingly, the air electrode for the metal air secondary battery of the present invention and the metal air secondary battery including the air electrode include zirconium-doped cerium oxide as a catalyst for oxygen reduction. In this case, the metal is preferably selected from the group consisting of Zn, Al, Mg, Fe, and Li.

Example 1

The cerium nitrate and zircon nitrate were dissolved in 100 ml of deionized water at pH 7 so that the molar ratio of Zr and Ce was 1: 9, and then the flammable liquid was calculated by [Equation 1] described above and added so that the concentration ratio was about 1.51. The solution was prepared. At this time, the reaction solution was carried out in a magnetic stirrer while applying heat. The stirring process is preferably continued until the amount of the solvent is about half.

After that, the reaction solution was ignited and burned completely while maintaining the temperature of 300 ° C. in the box furnace to perform the combustion reaction.

After the combustion reaction was completed, the remaining particles were recovered to obtain cerium oxide 1 (Z1) doped with zirconium.

Example 2

Zirconium-doped cerium oxide 2 (Z2) was obtained in the same manner as in Example 1 except that the molar ratio of Zr and Ce was 1: 4.

Here, a complete combustion process for doping zirconium (Zr) on the cerium oxide (Ce oxide) and the reaction scheme of the solvent used are as follows.

4Ce (NO ₃ ) ₃ + ZrO (NO ₃ ) ₂ + 7C ₂ H ₅ O ₂ N + 15O ₂ → _{5Ce 0.8 Zr 0.2 O 2 + 17.5H} 2 O + 21NO 2 + 14CO 2

Example 3

Zirconium-doped cerium oxide 3 (Z3) was obtained in the same manner as in Example 1 except that the molar ratio of Zr and Ce was set to 3: 7.

Example 4

Zirconium-doped cerium oxide 4 (Z4) was obtained in the same manner as in Example 1 except that the molar ratio of Zr and Ce was set to 2: 3.

Example 5

Zirconium-doped cerium oxide 5 (Z5) was obtained in the same manner as in Example 1 except that the molar ratio of Zr and Ce was set to 1: 1.

Experimental Example 1

Z1 (Ce _0.9 Zr _0.1 O ₂ ), Z2 (Ce _0.8 Zr _0.2 O ₂ ), Z3 (Ce _0.7 Zr _0.3 O ₂ ), Z4 (Ce _0.6 Zr _0.4 O ₂ ), Z5 (Ce) obtained in Examples 1 to 5 _0.5 Zr _0.5 O ₂ ) In order to observe the structure and morphological characteristics of the named material, the XRD composition was observed through X-ray diffraction analysis, and the result graph is shown in FIG. 1.

From the pattern shown in Figure 1 shows that the peak moved higher than the 2 Theta (Theta) value. In addition, it can be seen that the crystals of the prepared specimens Z1 to Z5 have hexagonal fluorite structure crystals. The lattice parameter a decreases from 5.392 to 5.290 even though the Zr atoms are fixed in the crystal structure. The reduction in these lattice parameters occurs while atoms of (Zr ⁴⁺ ) and smaller than the original ion size (Ce ⁴⁺ ) are inserted into the lattice. The particle size was calculated using FWHM for high intensity XRD peaks, and the size varied between 5 and 20 nm. The particle size of the Z 2 specimens was the smallest at 5 nm and the largest was Z 5.

Experimental Example 2

In order to observe the structure and the morphological characteristics of Z1 to Z5 obtained in Examples 1 to 5 were observed by SEM and the resulting pictures are shown in FIG.

SEM images of Z1, Z2, Z3, and Z4 specimens from FIG. 2 show a porous structure in which particles of 5-20 nm are aggregated. However, the Z5 specimen shows a compact form. The surface of the Z4 and Z5 specimens shows a small amount of ZrO ₂ impurities. The particle size calculated from the SEM is obtained from Scherer's formula.

Experimental Example 3

In order to observe the structure and the morphological characteristics of Z1 to Z5 obtained in Examples 1 to 5 were observed by TEM and the result photographs are shown in FIG.

It can be clearly seen from the TEM images shown in FIG. 3 that the particle size of Z 2 is smaller than the size of other specimens. The calculated value of particle size using TEM image is also accurate from XRD. Figure 3 also shows the pattern of a selected area diffraction pattern of the Z2 specimen. This pattern is an index corresponding to the face of the crystal lattice.

Experimental Example 4

The XPS spectra of Ce 3d, O1s and Zr 3d of the specimens Z1 to Z5 obtained in Examples 1 to 5 were observed and the results are shown in FIG. 4.

The spectrum of Ce3d from Figure 4 shows that the percentage decrease of Ce and increase with the addition of Zr. The oxygen content in Z1-Z5 is about the same. However, the oxygen peak showed two binding energies. The peak O1s spectrum that occurs at 532 eV is related to oxygen bonding with Ce in the Ce ₃ O ₄ array. That is, oxygen occupies octahedral sites while Ce atoms occupy tetrahedral sites in the unit grid. While the peak is 530 eV, the reference XPS line corresponds to O1s. These changes in the XPS line of O1s suggest that Ce was reduced from Ce ⁴⁺ to Ce ³⁺ as a result of Zr insertion.

Experimental Example 5

The specimens of Z1 to Z5 obtained in Examples 1 to 5 were observed for BET surface area change according to the amount of Zr added, and the results are shown in FIG. 5.

It is observed from FIG. 5 that the surface areas of the specimens Z1, Z2, Z3 are more than 55 m ² / g, but the remaining specimens Z4 and Z5 are very small. The reason for obtaining the high surface area was obtained because of the natural porosity of the material. In particular, the Z 2 specimens obtained high surface area values of 58.8 m ² / g. The reduction of the surface area due to the addition of Zr is expected to be due to the large pore size and the low porosity due to the large addition.

Example 6

1. Anode manufacturing of air cells

The anode of the air cell was manufactured by applying ink to the current collector followed by roll press. To prepare the ink, acetylene black (Sebang Battery Co.) was used together with poly vinylidene fluoride (Aldrich). N-methyl-2-pyrrolidinone (Acros Chemicals) was used as the binder, and the developed catalyst material, ie, the zirconium-doped cerium oxide (Z1) obtained in Example 1, was also added to the ink. The ink contained a carbon (acetylene black): catalyst (zirconium-doped cerium oxide 1: Z1): Binder (PVDF) in a weight ratio of 80:10.

The ink prepared by this process was manually painted on Ni foam, which acts as a current collector. By the same method, the electrodes contained 3-4 mg of active material (carbon + catalyst). The electrodes were then dried at 130 ° C and roll pressed to enhance the adhesion of the materials in the current collector.

2. Lithium air secondary battery manufacturing

The 2032 type coin cell was manufactured by Wellcos corp, and the anode part was drilled through a hole (diameter 1mm) for contact with air and assembled in a glove box in an Ar atmosphere.

As shown in FIG. 6, the coin cell has a circular anode (air electrode) having a diameter of 15.9 mm and is adjacent to a PTFE filter, and the Li metal electrode serves as a cathode having a thickness of 0.3 mm and a diameter of 12.5 mm. do. Each electrode was separated by a single layer microporous polypropylene laminated PP nonwoven fabric separator (Celgard USA) with a thickness of 25 mm. 1M LiTFSI {Lithium Bis (trifluoromethane) Sulfon Imide, Aldrich} in EC (Ethylene carbonate, Aldrich): Non-aqueous electrolyte containing PC (propylene carbonate, Aldrich) (1: 1 by weight%) The injected stainless steel disk is placed on top of the Li metal electrode to act as the current collector of the cathode, and the stainless steel spring is placed on the SS spacer before vacuum sealing with the cell and stainless steel cap. Plasctic gaskets were used to electrically insulate the positive and negative electrodes, respectively, and to seal the cells with vacuum.

As described above, a lithium-air battery 1 (Z1) including a zirconium-doped cerium oxide as a catalyst was prepared.

Example 7

A lithium-air battery 2 (Z2) was prepared in the same manner as in Example 6 except that zirconium-doped cerium oxide 2 (Z2) was used as a catalyst.

Example 8

A lithium-air battery 3 (Z3) was prepared in the same manner as in Example 6 except that zirconium-doped cerium oxide 3 (Z3) was used as a catalyst.

Example 9

A lithium-air battery 4 (Z4) was prepared in the same manner as in Example 6 except that zirconium-doped cerium oxide 4 (Z4) was used as a catalyst.

Example 10

A lithium-air battery 5 (Z5) was prepared in the same manner as in Example 6 except that zirconium-doped cerium oxide 5 (Z5) was used as a catalyst.

Experimental Example 6

The electrochemical impedance was measured for the lithium-air batteries 1 to 5 (cells Z1 to Z5) obtained in Examples 6 to 10, and the movement was measured from the frequency range of 0.01 Hz to 0.3 MHz, and the measured electrochemical impedance spectrum was measured. It is shown in Figure 7 (a). The equivalent circuit using the formatted data is also shown in Figure 7 (b).

Figure 7 (a) shows the Nyquist plot in the form of a semicircle, which coincides with the total electron transfer resistance of the cell. The equivalent circuit shown in Fig. 7 (b) contains three resistors, one of which is the contact resistance on the side of the cathode, and the other two are related to the resistance of the cathode and the anode portion. Cells containing Z2 show low resistance, and the porosity of the material allows electrons to easily pass through the electrolyte and thus increase the overall conductivity, which is why this lowers the overall charge transfer resistance.

Experimental Example 7

The oxygen reduction curves in Li / O ₂ cells of the lithium-air batteries 1 to 5 (batteries Z1 to Z5) obtained in Examples 6 to 10 were observed by cyclic voltammetry and shown in FIG. 8. The potentiostat was used to record the potential range of 2.2 V-4.4 V (vs. Li / Li ⁺⁾ and 0.5 mV / s scanning rate by cyclic voltammetry.

From FIG. 8, the cyclic voltammetry curve shows an exponential increase in current when the voltage is 2.8-0.295 V (.vs Li / Li ⁺ ). This increase in current is expected to be due to the following two types of electrochemical reactions that occur within a particular potential range.

2Li + O ₂ → Li ₂ O ₂ OCV = 2.959

4Li + O ₂ → 2Li ₂ O OCV = 2.913

In contrast, a peak is observed during the injection, which may be due to the decomposition of the product from the oxygen reduction reaction. In particular, the oxygen reduction reaction of the battery Z2 and the current value during decomposition of the battery Z4 were observed at the highest current density. This means that the battery Z2 contains the most effective oxygen reduction catalyst (catalyst Z2) and that the battery Z4 contains the most effective catalytic catalyst (catalyst Z4). The cell Z5 shows the worst catalytic activity of oxygen reduction, and it can be seen that the decomposition peak disappeared during the reverse injection.

Experimental Example 8

Discharge capacities were observed for the lithium-air batteries 1 to 5 (batteries Z1 to Z5) obtained in Examples 6 to 10, and the graphs are shown in FIG. The Li / O ₂ cell performance was then recorded with a current supply of 60 mA / g, and the calculation of specific capacity was calculated with the total weight of the active material in the air electrode.

9, it can be seen that an excellent one-step discharge curve was observed in the Li / O ₂ coin cell of the present invention, that is, the batteries Z1 to Z5. However, in the battery Z1 to which the catalyst Z1 is added, two flat sections are seen near 1.5 V during discharge. It has already been reported that such flat sections can cause decomposition of the electrodes. As the discharge capacity increases from 1422 mAh / g to 1620 mAh / g in the battery Z1 and Z2, respectively, the capacity of the Z3-Z5 cells decreases to 1331 mAh / g, 1056 mAh / g and 938 mAh / g. This is expected because the precipitation of the reaction product is similar to the small porous structure of the electrode, which blocks the oxygen diffusion path to the anode.

Clearly, the air electrode using the nanostructured catalyst Z2 (Ce _0.8 Zr _0.2 O ₂ ) exhibited the largest discharge capacity of 1620 mAh / g in the air electrode, cell Z2. Therefore, it can be seen that the improved dispersion of the zirconium-doped cerium oxide has a stable charging characteristic and a large discharge capacity of the Li / O ₂ battery. Therefore, it can be seen that the large surface area of the zirconium-doped cerium oxide catalyst according to the present invention leads to an improvement in the discharge capacity of the Li / O ₂ battery.

The above experimental results are summarized in Table 1 below.

The present invention has been shown and described with reference to the preferred embodiments as described above, but is not limited to the above embodiments and those skilled in the art without departing from the spirit of the present invention. Various changes and modifications will be possible.

Claims (14)

A cerium oxide, wherein zirconium represented by the following Chemical Formula 1 is doped and has hexagonal fluorite structure crystals.
[Chemical Formula 1]
Ce _1-x Zr _x O ₂ (0.1≤x≤0.5)
delete The method of claim 1,
The particle size of the oxide is zirconium-doped cerium oxide, characterized in that 5 to 20 nm.
A method for producing cerium oxide, wherein zirconium is doped in claim 1 or 3 and has hexagonal fluorite structure crystals.
A reaction solution preparation step of preparing a reaction solution by mixing cerium nitrate, zircon nitrate, water, and a flammable liquid;
A combustion step of combusting the reaction solution; And
The zirconium-doped cerium oxide manufacturing method comprising a; recovering step of recovering the remaining particles after the combustion step.
5. The method of claim 4,
Zirconium and cerium dissolved in the reaction solution is zirconium-doped cerium oxide manufacturing method characterized in that it has a molar ratio of 1: 1 to 1: 9.
5. The method of claim 4,
The concentration ratio of cerium nitrate, zircon nitrate and flammable liquid in the reaction solution is determined by the following formula 1 zirconium-doped cerium oxide manufacturing method.
[Equation 1]
Concentration ratio = C _c + C _z / C _f
C _c : absolute value of valence of cerium nitride x molar ratio of cerium
C _z : (absolute valence of zircon nitrate x molar ratio of zirconium
C _f : absolute value of valence of flammable liquid
5. The method of claim 4,
The combustion step is a zirconium-doped cerium oxide manufacturing method, characterized in that carried out by completely burning the reaction solution at a temperature of 250 to 350 ℃.
5. The method of claim 4,
The flammable liquids include Glycine [C ₂ H ₅ O ₂ N], Urea [CO (NH ₂ ) ₂ ], Citric acid [C ₆ H ₈ O ₇ ], Sucrose [C ₁₂ H ₂₂ O ₁₁ ], Ammonium nitrate [NH ₄ NO ₃ ], Polyvinyl alcohol [(C ₂ H ₄ O) n], Hexamine [C ₆ H ₁₂ N ₄ ], Oxalyl dihydrazide [ODH: C ₂ H ₆ O ₂ N ₄ ], Malonic acid dihydrazide [MDH: C ₃ H ₈ N ₄ O ₂ ] zirconium-doped cerium oxide manufacturing method characterized in that at least one selected from the group consisting of.
5. The method of claim 4,
Zirconium-doped cerium oxide manufacturing method, characterized in that the size of the remaining particles recovered in the recovery step is 5-20 nm.
The air electrode for a metal-air secondary battery comprising a cerium oxide as a catalyst, wherein the zirconium of claim 1 or 3 is doped and has hexagonal fluorite structure crystals.
11. The method of claim 10,
Wherein the metal is Zn, Al, Mg, Fe, Li, air electrode for a metal air secondary battery, characterized in that selected from the group consisting of.
11. The method of claim 10,
The air electrode comprises a carbon: zirconium-doped cerium oxide: binder 75 to 85: 5 to 20: the air electrode for a metal air secondary battery, characterized in that it comprises a weight ratio of the remaining amount.
Metal air secondary battery comprising the air electrode of claim 10. 14. The method of claim 13,
Wherein the secondary battery comprises Li, and the non-aqueous electrolyte is a metal electrode.

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