KR101451905B1 - Cathode Catalyst for Lithium-Air Battery, Method of Manufacturing the Same, and Lithium-Air Battery Comprising the Same - Google Patents

Abstract

The present invention relates to a positive electrode catalyst for a lithium-air battery, a process for producing the same, and a lithium-air battery including the same. A method for producing a cathode catalyst for a lithium-air battery according to the present invention comprises: a first step of preparing an electric spinning solution by mixing a carbon nanofibre precursor and a metal oxide precursor with a solvent; A second step of electrospinning the electrospinning liquid prepared in the first step to form a metal oxide-carbon nanofiber composite; And a third step of heat-treating the metal oxide-carbon nanofiber composite formed in the second step.
According to the cathode catalyst of the lithium-air battery manufactured according to the manufacturing method of the present invention, the oxygen reaction at the anode of the lithium-air battery can be promoted to lower the charging and discharging overvoltage and improve the energy efficiency.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive electrode catalyst for a lithium-air battery, a method for producing the same, and a lithium-air battery including the lithium-

The present invention relates to a positive electrode catalyst for a lithium-air battery, a process for producing the same, and a lithium-air battery including the same. More particularly, the present invention relates to a lithium- A positive electrode catalyst for a lithium-air battery, a method for producing the same, and a lithium-air battery including the same.

A lithium-air battery is a new energy storage device that can replace a conventional lithium ion battery, using lithium (Li) metal as the cathode and oxygen (O ₂ ) as the cathode active material. In the anode, lithium is oxidized / reduced, and in the anode, reduction / oxidation of oxygen introduced from the outside takes place, which is a combined battery system of a secondary battery and a fuel cell technology. The theoretical energy density of the lithium-air battery is 11,140 Wh / kg, which is very high compared to other secondary batteries.

The lithium-air battery typically comprises a cathode, an anode, an electrolyte disposed between the cathode and the anode, and a separator. The battery structure can be classified into three types depending on the electrolyte used.

First, non-aqueous lithium-air cells have advantages of simple structure and high energy density by using non-aqueous electrolyte. However, as the reaction product, solid Li ₂ O ₂ , continues to discharge, There is a problem that the electrolysis is terminated prematurely and the electrolyte is decomposed. Also, since the overvoltage at the air electrode is high, the charging and discharging energy efficiency is low.

Water-based lithium-air cells have the advantages of high operating voltage and low overvoltage at the cathode compared to organic lithium-air cells using aqueous electrolytes, but a protective film technique is required to prevent direct contact between the lithium anode and the water-soluble electrolyte to be.

Finally, the hybrid lithium-air battery has a structure in which a non-aqueous electrolyte is used on the lithium negative electrode side and an aqueous electrolyte is used on the air electrode side, and the two electrolytes are separated using a lithium ion conductive solid electrolyte membrane. It is a structure combining the advantages of non-aqueous and aqueous lithium-air batteries. It has advantages of suppressing direct contact between lithium anode and water, and low overvoltage at the air electrode, resulting in high charge and discharge energy efficiency.

Generally, porous carbon is included as a component of a hybrid lithium-air battery anode. However, since it has a low activity against an oxygen reduction / oxidation (generation) reaction, overvoltage during charging and discharging is higher than the theoretical value, . Therefore, it is necessary to develop a catalyst capable of promoting the oxygen reaction at the anode of the hybrid lithium-air battery so as to lower the overvoltage and improve the energy efficiency.

Considering the problems of the prior art, the present invention provides a positive electrode catalyst for a lithium-air battery capable of promoting an oxygen reaction at an anode of a lithium-air battery to lower charging and discharging overvoltage and improve energy efficiency, And an object of the present invention is to provide a lithium-air battery.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a carbon nanofiber precursor and a metal oxide precursor. A second step of electrospinning the electrospinning liquid prepared in the first step to form a metal oxide-carbon nanofiber composite; And a third step of subjecting the metal oxide-carbon nanofiber composite formed in the second step to a heat treatment. The present invention also provides a method for manufacturing a cathode catalyst for a lithium-air battery.

The carbon nanofiber precursor may be at least one selected from the group consisting of polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), polymethylmethacrylate (PMMA), polyvinyl alcohol (PVA) Polyvinyl acetate, polyvinylacetate (PVAC), polyfurfuryl alcohol, cellulose, glucose, polyvinylchloride (PVC), polyacrylic acid, polylactic acid, polyethylene (PEI), polypyrrole, polyimide, polyamideimide, polyaramid, polyaniline (PANI), phenolic resin, and pitch. One or more materials may be used.

The metal oxide precursor may be selected from the group consisting of manganese acetate (Mn (CO ₂ CH ₃ ) ₂ ), iron acetate (Fe (CO ₂ CH ₃ ) ₂ ), nickel acetate (Ni (CO ₂ CH ₃ ) ₂ ), cobalt acetate ₂ CH _{3) 2),} zinc acetate _{(Zn (CO 2 CH 3)} 2), copper acetate _{(Cu (CO 2 CH 3)} 2), manganese nitrate _{(Mn (NO 3) 2)} , iron nitrate (Fe (NO ₃ ) ₂ , Fe (NO ₃ ) ₃ ), Ni (NO ₃ ) ₂ , Cu (NO ₃ ) ₂ ), magnesium nitrate Mg (NO ₃ ) ₂ , cobalt NO _{3) 2),} manganese chloride (MnCl _2), titanium chloride (TiCl _4, or TiCl _3), tin hydrate _{(SnCl 2 · H 2 O)} , iron chloride (FeCl _3), nickel chloride (NiCl _2), copper chloride One or more materials selected from the group consisting of CuCl ₂ , MgCl ₂ , PdCl ₂ , CoCl ₂ and TaCl ₂ can be used.

The solvent may be one or more selected from the group consisting of distilled water, dimethylformamide, phenol, toluene, ethanol, methanol and propanol.

The electrospinning may be performed by supplying the electric discharge solution at a flow rate of 0.1 to 1 ml / h and applying a voltage of 10 to 25 kV.

The third step may include a first heat treatment step of heat-treating the composite at a temperature of 200 to 300 ° C in an argon atmosphere.

The third step may further include a second heat treatment step of performing the heat treatment of the composite body at a temperature of 500 to 700 ° C. in a mixed gas atmosphere of argon and air after the first heat treatment step.

The present invention also provides a positive electrode catalyst for a lithium-air battery produced using the above-described method.

The present invention also provides a positive electrode for a lithium-air battery comprising the positive electrode catalyst for a lithium-air battery, a carbonaceous material and a binder.

The carbon-based material may include one or more carbon-based materials selected from the group consisting of carbon black, activated carbon, graphite, graphene, and carbon fiber.

Wherein the binder is selected from the group consisting of vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, polytetrafluoroethylene, and styrene butadiene rubber polymers. Or two or more materials.

The present invention also provides a positive electrode for a lithium-air battery, comprising: An aqueous electrolyte in contact with the anode; A negative electrode comprising lithium metal or a lithium alloy; A non-aqueous electrolyte in contact with the negative electrode; And a lithium ion conductive solid electrolyte membrane sandwiched between the positive electrode and the negative electrode.

The water-based electrolyte may be made by including one or two or more kinds of lithium salts selected from the group consisting of LiOH, LiNO _3, LiCl, and CH ₃ COOLi.

The non-aqueous electrolyte may include an organic solvent and a lithium salt.

The organic solvent may be at least one selected from the group consisting of propylene carbonate, ethylene carbonate, fluoroethylene carbonate, diethyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, butylene carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, But are not limited to, butyrolactone, dioxolane, 4-methyldioxolane, N, N-dimethylformamide, dimethylacetamide, dimethylsulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, Dimethyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl propyl carbonate, dipropyl carbonate, dibutyl carbonate, diethylene glycol, dimethyl ether, dimethyldiglycol, dimethyltriglycol And dimethyltetraglycol, and at least one of them It may be made, including the material.

Wherein the lithium salt is selected from the group consisting of LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x and y are natural numbers), LiCl and LiI have.

The solid electrolyte membrane may comprise glass, ceramics or glass-ceramics.

Wherein the glass-ceramic is one or more than one selected from the group consisting of lithium-aluminum-germanium-phosphate (LAGP), lithium-aluminum- titanium- phosphate (LATP) and lithium- aluminum- titanium- Materials can be used.

According to the cathode catalyst of the lithium-air battery manufactured according to the manufacturing method of the present invention, the oxygen reaction at the anode of the lithium-air battery can be promoted to lower the charging and discharging overvoltage and improve the energy efficiency.

1 is a conceptual diagram showing an electrospinning apparatus for producing carbon nanofibers including a metal oxide according to the present invention.
2 is a schematic view of a hybrid lithium-air battery.
Fig. 3 is an X-ray diffraction pattern of the manganese oxide-carbon nanofiber composite prepared in Example 1. Fig.
4 is a scanning electron micrograph of the manganese oxide-carbon nanofiber composite prepared in Example 1. Fig.
5 is a transmission electron microscope (TEM) and energy dispersion spectroscopy (EDS) evaluation result of the manganese oxide-carbon nanofiber composite prepared in Example 1. Fig.
FIG. 6 shows the results of RDE experiments in which the activity for the oxygen reduction of the anode catalyst prepared in Example 1 and Comparative Examples 1 and 2 was measured.
FIG. 7 shows the results of RDE experiments in which the activity of the anode catalyst prepared in Example 1 and Comparative Examples 1 and 2 was measured for oxygen oxidation (generation). FIG.
8 is a graph showing charging and discharging curves of the lithium-air battery produced in Example 1 and Comparative Examples 1 and 2. FIG.

Hereinafter, the present invention will be described in detail. In the following description of the present invention, a detailed description of known configurations and functions will be omitted.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and should be construed in accordance with the technical meanings and concepts of the present invention.

The embodiments described in the present specification and the configurations shown in the drawings are preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention and thus various equivalents and modifications Can be.

A method for producing a cathode catalyst for a lithium-air battery according to the present invention comprises: a first step of preparing an electric spinning solution by mixing a carbon nanofibre precursor and a metal oxide precursor with a solvent; A second step of electrospinning the electrospinning liquid prepared in the first step to form a metal oxide-carbon nanofiber composite; And a third step of heat-treating the metal oxide-carbon nanofiber composite formed in the second step.

According to the method for producing a cathode catalyst for a lithium-air battery of the present invention, a carbon nanofiber precursor and a metal oxide precursor are mixed with a solvent to prepare an electric spinning solution.

Examples of the carbon nanofiber precursor include polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), polymethylmethacrylate (PMMA), polyvinyl alcohol (PVA) Polyvinyl acetate (PVA), polyvinylacetate (PVAc), polyfurfuryl alcohol, cellulose, glucose, polyvinylchloride (PVC), polyacrylic acid, polylactic acid ), Polyethylene oxide (PEO), polypyrrole, polyimide, polyamideimide, polyaramid, polyaniline (PANI), phenol resin or pitch can be used have.

As the metal oxide precursor, manganese acetate (Mn (CO ₂ CH ₃ ) ₂ ), iron acetate (Fe (CO ₂ CH ₃ ) ₂ ), nickel acetate (Ni (CO ₂ CH ₃ ) ₂ ), cobalt acetate _{Co (CO 2 CH 3) 2} ), zinc acetate _{(Zn (CO 2 CH 3)} 2), copper acetate _{(Cu (CO 2 CH 3)} 2), manganese nitrate _{(Mn (NO 3) 2)} , iron nitrate ( _{Fe (NO 3) 2, Fe} (NO 3) 3), nickel nitrate _{(Ni (NO 3) 2)} , copper nitrate _{(Cu (NO 3) 2)} , magnesium nitrate _{(Mg (NO 3) 2)} , cobalt nitrate _{(Co (NO 3) 2)} , manganese chloride (MnCl _2), titanium chloride (TiCl _4, or TiCl _3), tin hydrate _{(SnCl 2 · H 2 O)} , iron chloride (FeCl _3), nickel chloride (NiCl ₂₎ , Cupric chloride (CuCl ₂ ), magnesium chloride (MgCl ₂ ), palladium chloride (PdCl ₂ ), cobalt chloride (CoCl ₂ ) or tantalum chloride (TaCl ₂ ) can be used.

As the solvent, distilled water, dimethylformamide, phenol, toluene, ethanol, methanol or propanol may be used.

Next, the electrospinning solution is electrospunning to form a metal oxide-carbon nanofiber composite.

At this time, the electric spinning solution may be maintained at 70 ° C or lower, the electric spinning solution may be supplied at a flow rate of 0.1 to 1 mL / h, and the electrospinning may be performed by applying a voltage of 10 to 25 kV.

When the voltage falls below the lower limit of the above range, there is a problem that the electric discharge solution does not reach the collecting part. When the voltage exceeds the upper limit of the above range, the electric discharge solution is agglomeration, It is not preferable because a problem such as a phenomenon of being collected in the collecting part occurs.

Finally, the metal oxide-carbon nanofiber composite is heat-treated.

This step can be accomplished by the following two-stage heat treatment process.

First, the metal oxide-carbon nanofiber composite material is first heated to 200 to 300 ° C, and then subjected to a first heat treatment in an argon (Ar) atmosphere for 3 to 5 hours.

The first heat treatment process may remove some water and impurities remaining in the electric spinning solution and stabilize the carbon components present in the spinning fiber-type composite so that the fiber type skeleton can be maintained.

If the temperature of the first heat treatment step is less than 200 ° C, it may be difficult to remove some impurities. If the temperature exceeds 300 ° C, the carbon content in the electric discharge solution may be volatilized, which is not preferable.

If the first heat treatment is performed in air, it is preferable to perform the first heat treatment in an inert gas atmosphere such as Ar because there is a possibility that the carbon component is volatilized due to reaction with oxygen to destroy the fiber form.

After the first heat treatment, the metal oxide-carbon nanofiber composite is heated to 500 to 700 ° C and then subjected to a secondary heat treatment in a mixed gas atmosphere of argon (Ar) and air for 1 to 5 hours.

The two-step heat treatment is preferably carried out in a mixed atmosphere of Ar and a part of air in order to produce manganese oxide having a desired composition and structure. If only Ar is used, undesirable manganese oxides such as MnO are formed, which is undesirable. If heat treatment is performed only in air, there is a problem that only the manganese oxide is left due to volatilization of the fibrous carbon structure.

The second stage heat treatment temperature is preferably from 500 to 700 ° C. In order to synthesize Mn ₃ O ₄ and Mn ₂ O ₃ capable of acting as catalysts in the manganese oxide, when the temperature is raised to 700 ° C. or higher, the manganese oxide is decomposed , An undesirable composition of manganese oxide may be generated, which is undesirable.

The positive electrode for a lithium-air battery of the present invention comprises a positive electrode catalyst for a lithium-air battery, a carbonaceous material and a binder manufactured by the manufacturing method of the present invention.

The positive electrode for a lithium-air battery of the present invention may be formed, for example, by molding the positive electrode material composition containing the positive electrode catalyst, the carbonaceous material and the binder into a predetermined shape, or the positive electrode material composition may be a nickel mesh, carbon paper, or the like. A separate conductive material, solvent, etc. may be added to the cathode material composition.

Specifically, a cathode material composition is prepared and directly coated on a nickel mesh and a carbon paper current collector, or a cathode material film cast on a separate support and peeled from the support is laminated on a nickel mesh and a carbon paper current collector, Can be obtained. However, this is illustrative only, and the anode for a lithium-air battery of the present invention may be in a form other than those listed above.

Examples of the carbon-based material included in the cathode material composition include carbon black, graphite, graphene, activated carbon, carbon fiber, and the like.

As the binder, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene or styrene butadiene rubber polymer may be used. As the solvent, N-methylpyrrolidone (NMP), acetone, water and the like can be used.

In the cathode material composition, the content of the anode catalyst, the carbonaceous material, the binder and the solvent can be controlled within a range that is commonly used in a lithium-air battery.

The lithium-air battery of the present invention comprises the positive electrode for the lithium-air battery of the present invention; An aqueous electrolyte in contact with the anode; A negative electrode comprising lithium metal or a lithium alloy; A non-aqueous electrolyte in contact with the negative electrode; And a lithium ion conductive solid electrolyte film interposed between the anode and the cathode.

The negative electrode may be a lithium metal, a lithium alloy, or a lithium intercalating compound capable of intercalating and deintercalating lithium ions.

The non-aqueous electrolyte acts as a medium through which lithium ions can move, and an organic solvent that does not contain water can be used.

The organic solvent may be at least one selected from the group consisting of propylene carbonate, ethylene carbonate, fluoroethylene carbonate, diethyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, butylene carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, But are not limited to, butyrolactone, dioxolane, 4-methyldioxolane, N, N-dimethylformamide, dimethylacetamide, dimethylsulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, Dimethyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl propyl carbonate, dipropyl carbonate, dibutyl carbonate, diethylene glycol, dimethyl ether, dimethyldiglycol, dimethyltriglycol , tetraethylene glycol dimethyl or LiPF _6, LiBF _4, L in a solvent such as a mixture thereof iSbF _6, LiAsF _{6, 4} LiClO, LiCF SO _{3 3,} Li (CF ₃ SO ₂₎ N _2, LiC _{4 9} F SO _3, LiSbF _6, LiAlO _{4, 4} LiAlCl, LiN (C _x F SO _{2 2x +1} ) (C _y F _{2y + 1} SO ₂ ) (where x and y are natural numbers), LiCl, LiI, or a mixture thereof.

The lithium ion conductive solid electrolyte layer protects water contained in the aqueous electrolyte from reacting directly with lithium contained in the anode, and may be a glass, ceramic, or glass-ceramic material. For example, the ceramic material may be Li _{1 + x + y} (Al, Ga) _x (Ti, Ge) _2-x SiyP _3-y O _{12 where} 0 _{? X} ? 1, 0 _{? Y?} (LAGP), lithium-aluminum-titanium-phosphate (LATP) or lithium-aluminum-titanium-silicon-phosphate (LATSP) may be used as the glass-ceramics.

The aqueous electrolyte acts as a medium through which ions involved in an electrochemical reaction of a lithium-air battery can move, and is a solution in which a lithium salt is dissolved in water. For example, the lithium salt can be _{LiOH, LiNO 3, LiCl, CH} 3 COOLi , or a mixture thereof.

The non-aqueous and aqueous electrolytes may be impregnated into a porous separator. The separator may be any as long as it is commonly used in a lithium battery. Particularly, it is preferable that the electrolytic solution has a low resistance against the ion movement of the electrolyte and an excellent electrolytic solution impregnation ability. For example, selected from glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof, and may be nonwoven fabric or woven fabric.

Specifically, a windable separator such as polyethylene, polypropylene or the like, or a separator excellent in the ability to impregnate the organic electrolyte is used.

The lithium-air battery is also suitable for applications requiring high capacity such as an electric vehicle, and can be used in a hybrid vehicle or the like in combination with a conventional internal combustion engine, a fuel cell, and a supercapacitor. In addition, the lithium-air battery can be used for all other applications requiring a high capacity such as a cellular phone, a portable computer, and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are only for describing the present invention in more detail and that the scope of the present invention is not limited by these embodiments in accordance with the gist of the present invention .

Example  One

1. Preparation of an anode catalyst

As the polymer, polyacrylonitrile (PAN) was used as the polymer, manganese acetate (Mn (CO ₂ CH ₃ ) ₂ ) was used as the metal oxide precursor, and N, N-dimethylformamide (DMF) . Polyacrylonitrile (1.5 g) and manganese acetate (1.5 g) were dissolved in dimethylformamide (45 g) and homogenized at room temperature for about 48 hours to prepare an electrospinning solution. The electric discharge fluid thus prepared was placed in a syringe and supplied at a flow rate of 0.5 mL / h using a syringe pump, and a voltage of 15 kV was applied for electrospinning. At this time, the distance from the tip of the nozzle to the trapping portion was fixed to 20 cm, and the nanofiber was obtained by using a drum type trapping portion for uniform collection. The manganese oxide-carbon nanofiber composite obtained through the above process was stabilized at 280 ° C. for 5 hours in an argon (Ar) atmosphere, and carbonization was carried out at 500 ° C. for 5 hours in a mixed gas atmosphere of argon and air (2 vol. To prepare a carbon nanofiber cathode catalyst containing a metal oxide.

2. Manufacture of anode

The prepared anode catalyst, carbon black (Ketjen Black) and PTFE binder were mixed in a weight ratio of 30: 65: 5, and then a paste was prepared using ethanol. The paste was laminated to produce a film and dried at 60 DEG C for 24 hours. The film was laminated on both sides of a nickel mesh to prepare a positive electrode plate.

3. Manufacture of Lithium-Air Battery

1, an electrolyte in which a lithium negative electrode, 1M Li (CF ₃ SO ₂ ) ₂ N dissolved in dimethyltetraglycol, a separator and a LTAP solid electrolyte membrane were laminated, and then an aluminum pouch was used to form a part of the LATP solid electrolyte membrane Was exposed. A mixed electrolyte of 1 M LiNO ₃ and 0.5 M LiOH was dropped onto the negative electrode, and a positive electrode plate was laminated to prepare a hybrid lithium-air battery.

Comparative Example One

A positive electrode plate and a lithium-air cell were prepared in the same manner as in Example 1, except that the positive electrode paste was prepared by mixing a carbon black (Ketjen Black) and a PTFE binder in a weight ratio of 95: 5 without using a catalyst .

Comparative Example  2

Except that the manganese oxide-carbon nanofiber composite was not used as a catalyst but a commercially available manganese oxide (Mn ₃ O ₄ , Aldrich) catalyst was used, the positive electrode plate and the lithium-air battery .

Evaluation example  1: X-ray diffraction  Experiment

X-ray diffraction experiments were performed to understand the crystal structure of the manganese oxide-carbon nanofiber composite prepared in Example 1 above. The experimental results are shown in Fig. The anode catalyst prepared as shown in FIG. 3 is composed of amorphous carbon and crystalline Mn ₃ O ₄ (JCPDS 24-0734).

Evaluation example  2: Scanning electron microscope ( SEM ) Experiment

A scanning electron microscope (SEM) experiment was conducted to determine the shape of the manganese oxide-carbon nanofiber composite prepared in Example 1. [ The experimental results are shown in Fig. As shown in FIG. 4, it can be seen that the manganese oxide-carbon nanofiber composite prepared in the present invention is in a fibrous form having a diameter of several hundred nanometers.

Evaluation example  3: Transmission electron microscope ( TEM ) And energy dispersion spectroscopy ( EDS ) Experiment

Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) experiments were conducted to understand the shape and distribution of the catalysts of Example 1 above. The experimental results are shown in Fig. As shown in FIG. 5, carbon (C), manganese (Mn), and oxygen (O) components are compounded on the fibrous surface and are uniformly distributed.

Evaluation example  4: Rotating  Disk electrode RDE ) Experiment

Rotating Disk Electrode (RDE) experiments were conducted to evaluate the activity of the cathode catalysts prepared in Example 1 and Comparative Examples 1 and 2. The anode catalyst and the carbon black (Ketjen Black) were mixed so as to have a weight ratio of 50:50 (the weight ratio of the catalyst and carbon black in Comparative Example 1 was 0: 100) and then dispersed in distilled water to prepare a slurry for RDE electrode. The slurry thus formed was dripped onto a glassy carbon film used as a base material for RDE, followed by dropping Nafion solution (5 wt.%) And drying to prepare an RDE electrode. The performance of the catalyst was evaluated using platinum wire and Ag / AgCl electrode as counter electrode and reference electrode, respectively, as the working electrode.

The oxygen reduction activity was evaluated by saturating the oxygen in the electrolyte and then recording the current by scanning the potential in the negative direction from the open circuit voltage (OCV) (scan rate: 10 mV / s, Rotation speed: 1200 rpm). FIG. 6 is a graph showing the results of RDE experiments in which the activity of the cathode catalyst prepared in Example 1 and Comparative Examples 1 and 2 was measured for oxygen reduction. As can be seen from Example 1, when the manganese oxide-carbon nanofiber composite was used as the anode catalyst, it showed higher activity than Comparative Examples 1 and 2.

The oxygen oxidation (generation) activity was evaluated by scanning the potential from the open circuit voltage in the positive direction while recording the current (scan rate: 10 mV / s, electrode rotation number: 1200 rpm). FIG. 7 shows the results of RDE experiments in which the activity of the anode catalyst prepared in Example 1 and Comparative Examples 1 and 2 was measured for oxygen evolution. As can be seen from Example 1, when the manganese oxide-carbon nanofiber composite was used as the anode catalyst, it showed higher activity than Comparative Examples 1 and 2.

Evaluation example  5: Charging and discharging experiment of lithium-air battery

Charging and discharging experiments were carried out using the lithium-air cells prepared in Example 1 and Comparative Examples 1 and 2. [ More specifically, a constant current of 0.6 mA · cm ² was applied to discharge for 30 minutes. Thereafter, a constant current of 0.6 mA · cm ² was applied and charged for 30 minutes.

FIG. 8 shows charging and discharging curves of the lithium-air battery manufactured in Example 1 and Comparative Examples 1 and 2. FIG. As can be seen from Example 1, the lithium-air battery in which the manganese oxide-carbon nanofiber composite material is included as the positive electrode catalyst shows lower charge and discharge polarization than Comparative Examples 1 and 2. [

As described above, preferred embodiments of the present invention have been disclosed in the present specification and drawings, and although specific terms have been used, they have been used only in a general sense to easily describe the technical contents of the present invention and to facilitate understanding of the invention , And are not intended to limit the scope of the present invention.

It is to be understood by those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

Claims (18)

A carbon nanofiber precursor and a metal oxide precursor are mixed with a solvent to prepare an electric discharge solution;
A second step of electrospinning the electrospinning liquid prepared in the first step to form a metal oxide-carbon nanofiber composite; And
And a third step of heat-treating the metal oxide-carbon nanofiber composite formed in the second step,
Wherein the third step includes a first heat treatment step of heat-treating the composite at a temperature of 200 to 300 DEG C in an argon atmosphere,
And a second heat treatment step of subjecting the composite to a heat treatment at a temperature of 500 to 700 ° C. in a mixed gas atmosphere of argon and air after the first heat treatment step.
The method according to claim 1,
The carbon nanofiber precursor may be at least one selected from the group consisting of polyvinylpyrrolidone (PVP), polymethylmethacrylate (PMMA), polyvinyl alcohol (PVA), polyvinylacetate (PVAC) Polyvinyl chloride (PVC), polyacrylic acid, polylactic acid, polyethylene oxide (PEO), polypyrrole (polyvinyl alcohol), polyvinylpyrrolidone is characterized by being one or two or more kinds of substances selected from the group consisting of polypyrrole, polyimide, polyamideimide, polyaramid, polyaniline (PANI), phenol resin and pitch. Wherein the cathode catalyst is a lithium-air battery.
The method according to claim 1,
The metal oxide precursor may be selected from the group consisting of manganese acetate (Mn (CO ₂ CH ₃ ) ₂ ), nickel acetate (Ni (CO ₂ CH ₃ ) ₂ ), cobalt acetate (Co (CO ₂ CH ₃ ) ₂ ), zinc acetate ₂ CH _{3) 2),} copper acetate _{(Cu (CO 2 CH 3)} 2), manganese nitrate _{(Mn (NO 3) 2)} , iron nitrate _{(Fe (NO 3) 2,} Fe (NO 3) 3), nitric acid nickel _{(Ni (NO 3) 2)} , copper nitrate _{(Cu (NO 3) 2)} , magnesium nitrate _{(Mg (NO 3) 2)} , cobalt nitrate _{(Co (NO 3) 2)} , manganese chloride (MnCl _2), titanium chloride (TiCl _4, or TiCl _3), tin hydrate _{(SnCl 2 · H 2 O)} , iron chloride (FeCl _3), nickel chloride (NiCl _2), copper chloride (CuCl _2), magnesium chloride (MgCl _2), chloride Wherein the catalyst is one or two or more substances selected from the group consisting of palladium (PdCl ₂ ), cobalt chloride (CoCl ₂ ), and tantalum chloride (TaCl ₂ ).
The method according to claim 1,
Wherein the solvent is one or more selected from the group consisting of distilled water, phenol, toluene, ethanol, methanol, and propanol.
The method according to claim 1,
Wherein the electrospinning is performed by supplying the electric discharge liquid at a flow rate of 0.1 to 1 ml / h and applying a voltage of 10 to 25 kV.
delete delete A cathode catalyst for a lithium-air battery produced using the production method according to any one of claims 1 to 5.
A positive electrode for a lithium-air battery, comprising the positive electrode catalyst for a lithium-air battery according to claim 8, a carbon-based material and a binder.
10. The method of claim 9,
Wherein the carbon-based material comprises one or more carbon-based materials selected from the group consisting of carbon black, activated carbon, graphite, graphene, and carbon fiber.
10. The method of claim 9,
Wherein the binder is selected from the group consisting of vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, polytetrafluoroethylene, and styrene butadiene rubber polymers. Or at least two kinds of materials. ≪ RTI ID = 0.0 > 11. < / RTI >
A positive electrode for a lithium-air battery according to claim 9;
An aqueous electrolyte in contact with the anode;
A negative electrode comprising lithium metal or a lithium alloy;
A non-aqueous electrolyte in contact with the negative electrode; And
And a lithium ion conductive solid electrolyte membrane interposed between the positive electrode and the negative electrode.
13. The method of claim 12,
The aqueous electrolyte is LiOH, LiNO _3, LiCl and Li, characterized in that comprises one or two or more kinds of lithium salts selected from the group consisting of CH ₃ COOLi - air cell.
13. The method of claim 12,
Wherein the non-aqueous electrolyte comprises an organic solvent and a lithium salt.
15. The method of claim 14,
The organic solvent may be at least one selected from the group consisting of propylene carbonate, ethylene carbonate, fluoroethylene carbonate, diethyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, butylene carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, But are not limited to, butyrolactone, dioxolane, 4-methyldioxolane, N, N-dimethylformamide, dimethylacetamide, dimethylsulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, Dimethyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl propyl carbonate, dipropyl carbonate, dibutyl carbonate, diethylene glycol, dimethyl ether, dimethyldiglycol, dimethyltriglycol And dimethyltetraglycol, and at least one of them Lithium comprising the material-air battery.
15. The method of claim 14,
Wherein the lithium salt is selected from the group consisting of LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x and y are natural numbers), LiCl and LiI Lithium-air battery.
13. The method of claim 12,
Wherein the solid electrolyte membrane comprises glass, ceramics or glass-ceramics.
18. The method of claim 17,
Wherein the glass-ceramic is one or more than one selected from the group consisting of lithium-aluminum-germanium-phosphate (LAGP), lithium-aluminum- titanium- phosphate (LATP) and lithium- aluminum- titanium- Lt; RTI ID = 0.0 > Li-air < / RTI >

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