阅读说明：本技术 用于锂空气电池的电解质膜及其制造方法及包括其的锂空气电池 (Electrolyte membrane for lithium-air battery, method of manufacturing the same, and lithium-air battery including the same ) 是由 权恩汦 徐塞缪尔 吴光锡 康锡主 白京恩 于 2020-12-28 设计创作，主要内容包括：公开一种用于锂空气电池的电解质膜、制造该电解质膜的方法、用于锂空气电池的阴极、制造该阴极的方法,以及包括该电解质膜和阴极的锂空气电池。特别地,该锂空气电池包括：i)电解质膜,使用包括两种或多种氮氧化物的无机熔融混合物制造该电解质膜,并且该电解质膜因此具有非常低的低共熔点,和ii)阴极,通过在碳材料上快速还原金属而制造该阴极。因此,锂空气电池即使在低温下也能够稳定地工作并且提供高功率输出。(Disclosed are an electrolyte membrane for a lithium-air battery, a method of manufacturing the electrolyte membrane, a cathode for a lithium-air battery, a method of manufacturing the cathode, and a lithium-air battery including the electrolyte membrane and the cathode. Specifically, the lithium-air battery includes: i) an electrolyte membrane, which is manufactured using an inorganic molten mixture comprising two or more nitrogen oxides and which therefore has a very low eutectic point, and ii) a cathode, which is manufactured by rapidly reducing metals on carbon materials. Therefore, the lithium air battery can stably operate even at low temperature and provide high power output.)

1. A method of manufacturing an electrolyte membrane for a lithium air battery, comprising:

preparing inorganic salt;

preparing an inorganic melt mixture comprising the inorganic salt;

dipping a separator into the inorganic molten mixture; and

drying the impregnated separator.

2. The method of claim 1, wherein the inorganic salt comprises at least two nitrogen oxides.

3. The method of claim 1, wherein the inorganic salt comprises LiNO selected from lithium nitrate₃Potassium nitrate KNO₃Potassium nitrite KNO₂Cesium nitrate CsNO₃Sodium nitrate NaNO₃And calcium nitrate Ca (NO)₃)₂One or more of (a).

4. The method of claim 1, wherein the inorganic salt comprises two types of nitrogen oxides, three types of nitrogen oxides, four types of nitrogen oxides, or five types of nitrogen oxides.

5. The method of claim 4, wherein the two types of nitrogen oxides include lithium nitrate and potassium nitrate,

the three types of nitrogen oxides include lithium nitrate, potassium nitrate, and sodium nitrate; including lithium nitrate, potassium nitrate and calcium nitrate; or comprises lithium nitrate, potassium nitrite and cesium nitrate,

the four types of nitrogen oxides include lithium nitrate, potassium nitrate, sodium nitrate, and calcium nitrate, and

the five types of nitrogen oxides include lithium nitrate, potassium nitrate, cesium nitrate, sodium nitrate, and calcium nitrate.

6. The method of claim 1, wherein the inorganic salt comprises:

three types of nitroxides, which include lithium nitrate, potassium nitrite, and cesium nitrate,

four types of nitroxides including lithium nitrate, potassium nitrate, sodium nitrate and calcium nitrate, or

Five types of nitrogen oxides include lithium nitrate, potassium nitrate, cesium nitrate, sodium nitrate, and calcium nitrate.

7. The method of claim 6, wherein the three types of nitrogen oxides comprise 29 to 35 mole percent lithium nitrate, 51 to 56 mole percent potassium nitrite, and 10 to 15 mole percent cesium nitrate,

the four types of nitrogen oxides include 27 to 31 mole percent lithium nitrate, 38 to 50 mole percent potassium nitrate, 11 to 20 mole percent sodium nitrate, and 10 to 13 mole percent calcium nitrate, and

the five types of nitrogen oxides include 14 to 17 mol% of lithium nitrate, 29 to 31 mol% of potassium nitrate, 28 to 32 mol% of cesium nitrate, 9 to 11 mol% of sodium nitrate, and 13 to 18 mol% of calcium nitrate,

all mole% are based on the total moles of nitrogen oxides.

8. The method of claim 1, wherein the eutectic point of the inorganic salt is 130 ℃ or less.

9. The method of claim 6, wherein the eutectic point of the inorganic salt is 100 ℃ or less.

10. An electrolyte membrane for a lithium air battery made by the method of claim 1.

11. A method of manufacturing a cathode for a lithium air battery, comprising:

preparing a metal precursor mixture comprising a metal precursor;

preparing an electrode slurry comprising the metal precursor mixture and a carbon material;

coating the electrode paste on a substrate; and

the metal ions are reduced by applying a current to the coated electrode slurry.

12. The method of claim 11, wherein the metal precursor comprises one or more selected from the group consisting of platinum Pt, rubidium Ru, palladium Pd, rhodium Rh, nickel Ni, cobalt Co, iron Fe, copper Cu, and silver Ag.

13. The method of claim 11, wherein the carbon material comprises one or more selected from natural graphite, artificial graphite, carbon nanotubes, reduced graphene oxide rGO, carbon fibers, carbon black, ketjen black, acetylene black, mesoporous carbon, graphite, Denka black, fullerenes, and activated carbon.

14. The method according to claim 11, wherein the electrode paste comprises 40 to 60 parts by weight of the metal precursor, based on 100 parts by weight of the carbon material.

15. The method of claim 11, wherein the current is applied for 0.1 to 60 seconds.

16. The method of claim 11, wherein the magnitude of the current is 6A to 10A.

17. A cathode for a lithium air battery made by the method of claim 11.

18. A lithium-air battery, comprising:

a cathode comprising a carbon material;

an anode configured to face the cathode and including lithium metal that receives and releases lithium ions; and

the electrolyte membrane according to claim 10, which is interposed between the cathode and the anode.

19. The lithium air battery of claim 18, wherein the carbon material comprises one or more selected from natural graphite, artificial graphite, carbon nanotubes, reduced graphene oxide rGO, carbon fibers, carbon black, ketjen black, acetylene black, mesoporous carbon, graphite, Denka black, fullerenes, and activated carbon.

Technical Field

The present invention relates to an electrolyte membrane for a lithium-air battery, a method of manufacturing the electrolyte membrane, a cathode for a lithium-air battery, a method of manufacturing the cathode, and a lithium-air battery including the electrolyte membrane and the cathode. In particular, the lithium air battery may include: i) an electrolyte membrane that can be manufactured using an inorganic molten mixture (e.g., solution) including two or more nitrogen oxides, and which can thus have a very low eutectic point, and ii) a cathode manufactured by rapidly reducing a metal on a carbon material. Therefore, the lithium air battery can stably operate even at low temperature and provide high power output.

Background

The lithium-air secondary battery has a greater energy density than the lithium-ion secondary battery, and has an advantage of being able to operate using oxygen in the air. However, a side reaction may occur between the carbon-based electrode and the organic solvent-based electrolyte to deteriorate the performance of the battery, and research to solve the problem has been ongoing.

Organic solvent-based liquid electrolytes generally used for lithium air secondary batteries have high volatility and thus are easily evaporated during charge and discharge, cause loss due to leakage, and are unstable at high temperatures, making operation difficult.

Disclosure of Invention

In a preferred aspect, there is provided a lithium air battery capable of operating under various temperature conditions from a low temperature to a high temperature.

In a preferred aspect, there is provided a method of manufacturing a cathode by joule heating reaction capable of synthesizing a catalyst in a short time.

The objects of the present invention are not limited to the above objects and will be clearly understood by the following description, and can be achieved by the means described in the claims and combinations thereof.

In one aspect, a method of manufacturing an electrolyte membrane for a lithium air battery is provided. The method can comprise the following steps: preparing inorganic salt; preparing an inorganic melt mixture (e.g., solution) comprising an inorganic salt (e.g., by melting the inorganic salt); dipping the separator into the inorganic molten mixture; and drying the impregnated separator.

The inorganic salt may include at least two nitrogen oxides.

The term "nitroxide" as used herein refers to a nitrate of Nitrogen (NO) with i) a cationic metal (e.g., an alkali metal or alkaline earth metal cation) and ii) an anion₃ ^-) Or anionic Nitrite (NO)₂ ^-) The compound or salt formed. Exemplary nitroxides include metal cations (e.g., Li)⁺、Na⁺、K⁺、Rb⁺、Cs⁺、Mg²⁺、Ca²⁺、Sr²⁺Or Ba²⁺) And anionic Nitrate (NO)₃ ^-) Or an anionic Nitrite (NO)₂ ^-) The salt formed.

The inorganic salt may include a salt selected from lithium nitrate (LiNO)₃) Potassium nitrate (KNO)₃) Potassium nitrite (KNO)₂) Cesium nitrate (CsNO)₃) Sodium nitrate (NaNO)₃) And calcium nitrate (Ca (NO)₃)₂) One or more of (a).

The inorganic salt may include two types of nitrogen oxides, three types of nitrogen oxides, four types of nitrogen oxides, or five types of nitrogen oxides.

Two types of nitrogen oxides may suitably include lithium nitrate and potassium nitrate, and three types of nitrogen oxides may suitably include lithium nitrate, potassium nitrate and sodium nitrate; may include lithium nitrate, potassium nitrate and calcium nitrate; or may suitably include lithium nitrate, potassium nitrite, and cesium nitrate, the four types of nitrogen oxides may suitably include lithium nitrate, potassium nitrate, sodium nitrate, and calcium nitrate, and the five types of nitrogen oxides may suitably include lithium nitrate, potassium nitrate, cesium nitrate, sodium nitrate, and calcium nitrate.

The inorganic salt may suitably include: three types of nitroxides, which include lithium nitrate, potassium nitrite, and cesium nitrate; four types of nitrogen oxides including lithium nitrate, potassium nitrate, sodium nitrate, and calcium nitrate; or five types of nitrogen oxides including lithium nitrate, potassium nitrate, cesium nitrate, sodium nitrate, and calcium nitrate.

Three types of nitrogen oxides may include about 29 to 35 mol% lithium nitrate, about 51 to 56 mol% potassium nitrite, and about 10 to 15 mol% cesium nitrate, four types of nitrogen oxides may include about 27 to 31 mol% lithium nitrate, about 38 to 50 mol% potassium nitrate, about 11 to 20 mol% sodium nitrate, and about 10 to 13 mol% calcium nitrate, and five types of nitrogen oxides may include about 14 to 17 mol% lithium nitrate, about 29 to 31 mol% potassium nitrate, about 28 to 32 mol% cesium nitrate, about 9 to 11 mol% sodium nitrate, and about 13 to 18 mol% calcium nitrate. All mole% are based on the total moles of nitrogen oxides.

The inorganic salt may have a eutectic point of about 130 ℃ or less.

The inorganic salt may have a eutectic point of about 100 ℃ or less.

In one aspect, an electrolyte membrane for a lithium air battery is provided, made by the method described herein.

In one aspect, a method of manufacturing a cathode for a lithium air battery is provided. The method can comprise the following steps: preparing a metal precursor mixture (e.g., solution) comprising a metal precursor; manufacturing an electrode slurry comprising a metal precursor mixture and a carbon material; coating electrode slurry on a substrate; and reducing the metal ions by applying a current to the coated electrode paste.

The metal precursor may include one or more selected from the group consisting of platinum (Pt), rubidium (Ru), palladium (Pd), rhodium (Rh), nickel (Ni), cobalt (Co), iron (Fe), copper (Cu), and silver (Ag).

The carbon material may include one or more selected from natural graphite, artificial graphite, carbon nanotubes, reduced graphene oxide (rGO), carbon fibers, carbon black, ketjen black, acetylene black, mesoporous carbon, graphite, Denka black, fullerene, and activated carbon.

The electrode paste may include about 40 to 60 parts by weight of the metal precursor based on 100 parts by weight of the carbon material.

The current may be applied for about 0.1 seconds to 60 seconds.

The magnitude of the current may be about 6A to 10A.

In one aspect, a cathode for a lithium air battery manufactured by the above method is provided.

In one aspect, there is provided a lithium air battery, which may include: a cathode comprising a carbon material; an anode configured to face the cathode and including lithium metal that receives and releases lithium ions; and an electrolyte membrane as described herein interposed between the cathode and the anode.

The carbon material may include one or more selected from natural graphite, artificial graphite, carbon nanotubes, reduced graphene oxide (rGO), carbon fibers, carbon black, ketjen black, acetylene black, mesoporous carbon, graphite, Denka black, fullerene, and activated carbon.

According to various exemplary embodiments of the present invention, it is possible to provide a lithium air battery capable of operating under various temperature conditions from a low temperature to a high temperature.

According to various exemplary embodiments of the present invention, a method of manufacturing a cathode through a joule heating reaction capable of synthesizing a catalyst in a short time may be provided.

The effects of the present invention are not limited to the above, and should be understood to include all effects that can be reasonably expected from the following description.

Other aspects of the invention are disclosed below.

Drawings

FIG. 1 illustrates an exemplary process for manufacturing an exemplary electrolyte membrane, according to an exemplary embodiment of the invention;

FIG. 2 illustrates an exemplary configuration of an exemplary electrolyte membrane, according to an exemplary embodiment of the invention;

FIG. 3 illustrates an exemplary process of manufacturing an exemplary cathode according to an exemplary embodiment of the present invention;

FIG. 4 shows an exemplary configuration of an exemplary cathode according to an exemplary embodiment of the present invention;

fig. 5A and 5B are graphs showing the results of test example 1;

fig. 6A and 6B are graphs showing the results of test example 2;

fig. 7A to 7F are graphs showing the results of test example 3;

fig. 8A and 8B are graphs showing the results of test example 4;

fig. 9A and 9B are graphs showing the results of test example 5; and

fig. 10A to 10C are SEM images showing the cathode of the present invention in test example 6.

Detailed Description

The above and other objects, features and advantages of the present invention will become readily apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed herein, but may be modified in various forms. These embodiments are provided so that this disclosure will be thorough and will fully convey the spirit of the invention to those skilled in the art.

The same reference numbers will be used throughout the drawings to refer to the same or like elements. For clarity of the invention, the dimensions of the structures are described as being larger than actual dimensions. It will be understood that, although terms such as "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a "first" element discussed below could be termed a "second" element without departing from the scope of the present invention. Similarly, a "second" element may also be referred to as a "first" element. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise.

It will be further understood that the terms "comprises," "comprising," "includes" and the like, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof. Also, it will be understood that when an element (e.g., a layer, film, region, or sheet) is referred to as being "on" another element, it can be directly on the other element or intervening elements may be present therebetween. Similarly, when an element (e.g., a layer, film, region, or sheet) is referred to as being "under" another element, it can be directly under the other element or intervening elements may be present therebetween.

Unless otherwise indicated, all numbers, values, and/or representations representing amounts of components, reaction conditions, polymer compositions, and mixtures used herein are to be considered approximate, including the various uncertainties in effecting measurements that inherently occur when such values are obtained, and thus should be understood as modified in all instances by the term "about". Further, when a range of values is disclosed in this specification, unless otherwise stated, the range is continuous and includes all values from the minimum to the maximum of the range. Moreover, when such ranges refer to integer values, all integers from the minimum to the maximum are included unless otherwise indicated.

In addition, unless otherwise indicated or apparent from the context, the term "about" should be understood to be within the normal tolerance of the art, e.g., within 2 standard deviations of the mean. "about" can be understood as being within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05% or 0.01% of the stated value. Unless otherwise clear from the context, all numbers provided herein are modified by the term "about".

In this specification, when a range of a variable is described, it is to be understood that the variable includes all values that include the end points described within the range. For example, a range of "5 to 10" should be understood to include any subrange (e.g., 6 to 10, 7 to 10, 6 to 9, 7 to 9, etc.) as well as each value of 5, 6, 7, 8, 9, and 10, and also to include any value between the effective integers within the range (e.g., 5.5, 6.5, 7.5, 5.5 to 8.5, 6.5 to 9, etc.). Additionally, for example, a range of "10% to 30%" should be interpreted as including sub-ranges (e.g., 10% to 15%, 12% to 18%, 20% to 30%, etc.) as well as all integers including values from 10%, 11%, 12%, 13%, etc. up to 30%, and should also be interpreted to include any value between the effective integers within the range (e.g., 10.5%, 15.5%, 25.5%, etc.).

The present invention provides a method of manufacturing an electrolyte membrane for a lithium-air battery, an electrolyte membrane manufactured thereby, a method of manufacturing a cathode for a lithium-air battery, a cathode manufactured thereby, and a lithium-air battery including the electrolyte membrane and the cathode.

Fig. 1 and 3 are flowcharts respectively illustrating exemplary processes of manufacturing an electrolyte membrane and a cathode according to exemplary embodiments of the present invention. Referring to these drawings, the respective steps are specifically described below.

Method for manufacturing lithium-air battery

The method of manufacturing the lithium air battery may include: i) a method of manufacturing an electrolyte membrane and ii) a method of manufacturing a cathode.

The method of manufacturing an electrolyte membrane may include: preparing inorganic salt; preparing an inorganic melt mixture (e.g., solution) comprising an inorganic salt by melting the inorganic salt; dipping the separator into the inorganic molten mixture; and drying the impregnated separator. The method of manufacturing a cathode may include: preparing a metal precursor mixture (e.g., solution) including a metal precursor; preparing an electrode slurry comprising a metal precursor mixture and a carbon material; coating the electrode slurry on a substrate; and reducing the metal ions by applying a current to the coated electrode paste.

A method of manufacturing the electrolyte membrane and a method of manufacturing the cathode are described below, respectively.

Method for manufacturing electrolyte membrane for lithium-air battery

The method of manufacturing an electrolyte membrane for a lithium air battery may include: preparing inorganic salt; preparing an inorganic melt mixture (e.g., solution) comprising an inorganic salt by melting the inorganic salt; dipping the separator into the inorganic molten mixture; and drying the impregnated separator.

Fig. 1 illustrates an exemplary process of manufacturing an exemplary electrolyte membrane for a lithium air battery according to an exemplary embodiment of the present invention. Referring to fig. 1, the respective steps are described, and the electrolyte membrane thus manufactured is described with reference to fig. 2.

Preparation of inorganic salts

Inorganic salts may be prepared and may preferably include nitrogen oxides.

The oxynitride may include a material selected from lithium nitrate (LiNO)₃) Potassium nitrate (KNO)₃) Potassium nitrite (KNO)₂) Cesium nitrate (CsNO)₃) Sodium nitrate (NaNO)₃) And calcium nitrate (Ca (NO)₃)₂) And preferably comprises two or more different nitrogen oxides.

The inorganic salt may include two types of nitrogen oxides, three types of nitrogen oxides, four types of nitrogen oxides, or five types of nitrogen oxides. Preferably, the inorganic salt may include three to five types of nitrogen oxides.

Two types of nitrogen oxides may suitably include lithium nitrate and potassium nitrate, three types of nitrogen oxides may suitably include lithium nitrate, potassium nitrate and sodium nitrate, including lithium nitrate, potassium nitrate and calcium nitrate, or include lithium nitrate, potassium nitrite and cesium nitrate, four types of nitrogen oxides may suitably include lithium nitrate, potassium nitrate, sodium nitrate and calcium nitrate, and five types of nitrogen oxides may suitably include lithium nitrate, potassium nitrate, cesium nitrate, sodium nitrate and calcium nitrate.

Both types of nitrogen oxides may suitably comprise about 40 to 43 mole percent lithium nitrate and about 57 to 60 mole percent potassium nitrate. In the case where the compositional ratio is out of the above range, the region of the eutectic point in the phase equilibrium may be changed, which causes a problem that the melting point is largely changed, so that the desired effect of the present invention cannot be obtained.

The three types of nitrogen oxides may suitably comprise about 29 to 31 mole percent lithium nitrate, about 51 to 53 mole percent potassium nitrate, and about 17 to 19 mole percent sodium nitrate; suitably comprising about 30 to 32 mole% lithium nitrate, about 57 to 59 mole% potassium nitrate, and about 10 to 12 mole% calcium nitrate; or suitably from about 29 to 35 mole percent lithium nitrate, from about 51 to 56 mole percent potassium nitrite, and from about 10 to 15 mole percent cesium nitrate.

The four types of nitrogen oxides may suitably include about 27 to 31 mole percent lithium nitrate, about 38 to 50 mole percent potassium nitrate, about 11 to 20 mole percent sodium nitrate, and about 10 to 13 mole percent calcium nitrate.

The five types of nitrogen oxides may suitably include about 14 to 17 mole% lithium nitrate, about 29 to 31 mole% potassium nitrate, about 28 to 32 mole% cesium nitrate, about 9 to 11 mole% sodium nitrate, and about 13 to 18 mole% calcium nitrate.

The eutectic point may vary depending on the type, amount and amount of nitrogen oxides included in the inorganic salt.

The eutectic point of the inorganic salt including two or more types of nitrogen oxides may be about 130 ℃ or less.

The eutectic point of two types of nitrogen oxides may preferably be about 125 ℃ or less, the eutectic point of three types of nitrogen oxides may preferably be about 90 ℃ to 120 ℃, the eutectic point of four types of nitrogen oxides may preferably be about 95 ℃ or less, and the eutectic point of five types of nitrogen oxides may preferably be about 80 ℃ or less.

The eutectic point of the inorganic salt may preferably be about 100 ℃ or less. The inorganic salts may include: three types of nitrogen oxides consisting of lithium nitrate, potassium nitrite and cesium nitrate and having eutectic points of about 90 ℃ to 95 ℃; four types of nitrogen oxides consisting of lithium nitrate, potassium nitrate, sodium nitrate, and calcium nitrate and having a eutectic point of about 95 ℃ or less, or five types of nitrogen oxides consisting of lithium nitrate, potassium nitrate, cesium nitrate, sodium nitrate, and calcium nitrate and having a eutectic point of about 80 ℃ or less.

Making inorganic melt mixtures

The inorganic salt may be melted to provide an inorganic melt mixture. For example, an inorganic salt comprising two or more nitrogen oxides can be melted to provide an inorganic melt mixture. The composition of the nitrogen oxides contained in the inorganic molten mixture is the same as the composition of the nitrates contained in the inorganic salts.

Impregnation

The separator may be impregnated in the inorganic melt mixture prepared as described above, and thus the separator may be wetted with the inorganic melt mixture, and thus the inorganic melt mixture may be introduced and attached to the inside and outside of the separator.

Any separator may be used without limitation as long as the separator is generally used in the field of fuel cells and is resistant to a temperature of about 110 c or more, preferably about 130 c or more. Since the separator is impregnated with the inorganic molten mixture obtained by melting at a high temperature, the separator must have sufficient heat resistance to withstand the heat of the inorganic molten mixture. The separator may preferably comprise glass fibers.

Drying

The separator may be taken out of the inorganic molten mixture and dried to provide an electrolyte membrane.

Drying may be preferably performed at a temperature of about 60 ℃ or less in vacuum, and the drying method in the present invention is not particularly limited.

Electrolyte membrane for lithium-air battery

An electrolyte membrane for a lithium air battery may be manufactured by the method described herein, and the electrolyte membrane may include a separator and an inorganic molten mixture. The inorganic melt mixture may suitably comprise two to five types of nitrogen oxides, and preferably comprises three to five types of nitrogen oxides.

Fig. 2 illustrates an exemplary electrolyte membrane for a lithium-air battery according to an exemplary embodiment of the present invention. For example, an inorganic melt mixture may be introduced and attached to the inside and outside of the separator having holes.

Method of manufacturing cathode for lithium air battery

A method of manufacturing a cathode for a lithium air battery may include: preparing a metal precursor mixture (e.g., solution) including metal ions; preparing an electrode slurry comprising a metal precursor mixture and a carbon material; coating the electrode slurry on a substrate; and reducing the metal ions by applying a current to the coated electrode paste.

Fig. 3 is a flow chart of an exemplary process of manufacturing an exemplary cathode according to an exemplary embodiment of the present invention. Referring to fig. 3, the respective steps are described, and the cathode thus manufactured is described with reference to fig. 4.

Preparation of Metal precursor mixtures

A metal precursor mixture containing metal ions can be prepared. The metal precursor mixture can include a metal precursor.

The metal precursor may suitably include one or more metals selected from platinum (Pt), rubidium (Ru), palladium (Pd), rhodium (Rh), nickel (Ni), cobalt (Co), iron (Fe), copper (Cu), and silver (Ag).

The metal precursor is not particularly limited as long as it can be combined with the above metal and is soluble in water (H)₂O) is adopted. For example, the metal precursor includes Nitrate (NO) therein₃ ^-) Nitrite (NO)₂ ^-) Chloride ion (Cl)^-) Etc. in combination with metals. For example, the metal may be present in an ionic state by binding to an anion (e.g., nitrate, nitrite, or chloride).

Manufacture of electrode paste

The metal precursor mixture can be mixed with a carbon material to provide an electrode slurry.

The carbon material may suitably include one or more selected from natural graphite, artificial graphite, carbon nanotubes, reduced graphene oxide (rGO), carbon fibers, carbon black, ketjen black, acetylene black, mesoporous carbon, graphite, Denka black, fullerene, and activated carbon.

The metal precursor of the present invention may be preferably mixed in an amount of 40 to 60 parts by weight, based on 100 parts by weight of the carbon material.

Coating electrode paste

The electrode slurry may be coated on a substrate.

In the present invention, the type of the substrate is not particularly limited, and any substrate may be used as long as it provides a base on which the electrode paste can be uniformly coated and is conductive.

The process of applying the electrode paste is not particularly limited, and any process may be performed in the present invention as long as the electrode paste can be generally applied.

Reduction of

A current may be applied to the coated electrode slurry, and thus the metal ions may be reduced. In particular, the metal catalyst may be synthesized on the surface of the carbon material by joule heating reaction.

An electric current may be applied to both ends of the electrode paste coated and uniformly spread on the substrate. The magnitude of the applied current may preferably be about 6A to 10A for about 0.1 seconds to 60 seconds.

Cathode for lithium air battery

The cathode for a lithium-air battery according to the present invention may be manufactured by the method described herein, and the cathode may include a carbon material and a metal attached to the surface of the carbon material. The metal may suitably include one or more selected from platinum (Pt), rubidium (Ru), palladium (Pd), rhodium (Rh), nickel (Ni), cobalt (Co), iron (Fe), copper (Cu) and silver (Ag).

Fig. 4 illustrates an exemplary cathode for a lithium-air battery according to an exemplary embodiment of the present invention. Referring to fig. 4, metal ions are reduced and precipitated as metal particles on the surface of the carbon material forming the cathode skeleton.

Lithium air battery

A lithium air battery comprising: a cathode comprising a carbon material; an anode configured to face the cathode and including lithium metal that receives and releases lithium ions; and an electrolyte membrane interposed between the cathode and the anode.

The carbon material contained in the cathode may suitably include one or more selected from natural graphite, artificial graphite, carbon nanotubes, reduced graphene oxide (rGO), carbon fibers, carbon black, ketjen black, acetylene black, mesoporous carbon, graphite, Denka black, fullerene, and activated carbon.

The cathode of the present invention may include a carbon material having metal particles on the surface thereof.

The metal particles may be obtained by precipitation by reducing metal ions on the surface of the carbon material by a current applied from the outside, and may include one or more selected from the group consisting of platinum (Pt), rubidium (Ru), palladium (Pd), Rhodium (RH), nickel (Ni), cobalt (Co), iron (Fe), copper (Cu), and silver (Ag).

The anode is not limited as long as it is a type that can be generally used in a lithium air battery.

The electrolyte membrane may include a separator and an inorganic molten mixture. The inorganic melt mixture may include two to five types of nitrogen oxides, and preferably includes three to five types of nitrogen oxides as described herein.

Examples

The present invention will be better understood from the following examples, which, however, are merely illustrative of the present invention and should not be construed as limiting the scope of the present invention.

Preparation examples 1 and 2

Inorganic salts including a combination of nitrates, as shown in table 1 below, were prepared and then melted to provide an inorganic melt mixture. Then, the glass fiber membrane was immersed in the inorganic molten mixture and then slowly dried at room temperature, thereby manufacturing an electrolyte membrane.

TABLE 1

Preparation example 3

A carbon paper (P50) comprising a carbon material (Super P) was prepared, and a metal precursor solution RuCl was mixed in an amount of 50 parts by weight based on 100 parts by weight of the carbon material₃*H₂O to provide an electrode paste. The electrode slurry was coated on the carbon paper using a doctor blade. Then, both ends of the carbon paper and the electrode paste coated on the carbon paper were connected to a copper foil (external current was flowed through the copper foil), and then a current of 7A was applied and the temperature of the electrode paste was increased, thereby manufacturing a cathode.

Preparation example 4

An anode and a cathode including lithium metal foil were joined to each side of the electrolyte membrane manufactured in preparation example 1, thereby manufacturing a lithium-air battery. Here, the cathode is coated with RuO₂And PVDF (polyvinylidene fluoride) carbon paper.

Preparation example 5

An anode and a cathode including lithium metal foil were joined to each side of the electrolyte membrane manufactured in preparation example 2, thereby manufacturing a lithium-air battery. Here, the cathode is coated with RuO₂And PVDF (polyvinylidene fluoride) carbon paper.

Preparation example 6

An anode including lithium metal foil and a cathode manufactured in preparation example 3 were joined to each side of the electrolyte membrane manufactured in preparation example 1, thereby manufacturing a lithium-air battery.

Preparation example 7

An anode including lithium metal foil and a cathode manufactured in preparation example 3 were joined to each side of the electrolyte membrane manufactured in preparation example 2, thereby manufacturing a lithium air battery.

Test example 1

The melting points of the electrolyte membranes manufactured in each of preparation examples 1 and 2 were measured using Differential Scanning Calorimetry (DSC). As shown in fig. 5A and 5B, the results are shown: in preparation example 1 (fig. 5A) using inorganic salts including two types of salts, the eutectic point was 130 ℃, and in preparation example 2 (fig. 5B) using inorganic salts including five types of salts, the eutectic point was 68 ℃.

Test example 2

The lithium air batteries manufactured in preparation examples 4 and 5 were charged and discharged at 100 ℃, 120 ℃ and 150 ℃. The results are shown in fig. 6A and 6B. In particular, fig. 6A is a graph showing voltage versus capacity measured during charge and discharge of a lithium air battery including an electrolyte membrane manufactured using inorganic salts (including two types of salts), and fig. 6B is a graph showing voltage versus capacity measured during charge and discharge of a lithium air battery including an electrolyte membrane manufactured using inorganic salts (including five types of salts).

As shown in the graph of fig. 6B, the charge/discharge voltage difference is greatly reduced as the operating temperature increases.

Test example 3

The lithium-air battery of preparation example 5 was subjected to a charge/discharge test, and gas deposition was measured at the same time. The results are shown in fig. 7A to 7F. In particular, fig. 7A shows a voltage change when the lithium-air battery of preparative example 4 was charged and discharged at an operating temperature of 150 ℃, fig. 7C shows a voltage change when the lithium-air battery of preparative example 5 was charged and discharged at an operating temperature of 150 ℃, and fig. 7E shows a voltage change when the lithium-air battery of preparative example 5 was charged and discharged at an operating temperature of 100 ℃. In particular, fig. 7A, 7C, and 7E illustrate changes in voltage with respect to capacity when the lithium air battery is charged and discharged at the respective operating temperatures. The results of simultaneous gas evolution during each test are shown in sequence in fig. 7B, 7D and 7F.

Based on the results of fig. 7A to 7F, at the operating temperature of 150 ℃, oxygen reached a theoretical value in both the inorganic salt including two types of salts (nitrogen oxides) and the inorganic salt including five types of salts (nitrogen oxides), but when the operating temperature was low, specifically 100 ℃, oxygen evolution was slightly reduced.

Test example 4

The lithium air battery of preparation example 7 was charged and discharged, and gas evolution was analyzed in the same manner as in test example 3. The results are shown in fig. 8A and 8B. In particular, fig. 8A shows a graph of voltage versus capacitance that occurs when current is applied at an operating temperature of 100 ℃, while fig. 8B is a graph showing measurement results of simultaneous gas evolution.

Test example 5

For the lithium-air battery of production example 5 and the lithium-air battery of production example 7, voltage and power density were measured by applying a current of 0.01mA/s at 100 ℃. The results are shown in fig. 9A and 9B. Referring to fig. 9A and 9B, when the cathode of preparative example 3 was used, the power density increased by 10 times or more (the measurement result of the lithium-air battery of preparative example 5 is shown in fig. 9A, and the measurement result of the lithium-air battery of preparative example 7 is shown in fig. 9B).

Test example 6

For the lithium air batteries of preparation examples 6 and 7, the surfaces of the cathodes before and after discharge were observed using a Scanning Electron Microscope (SEM). The results are shown in fig. 10A to 10C. Fig. 10A shows the surface of the cathode before the lithium-air battery of preparative example 6 was discharged, and fig. 10B shows the surface of the cathode after the lithium-air battery of preparative example 6 was discharged at 150 ℃. Fig. 10C shows the surface of the cathode after the lithium-air battery of preparation example 7 was discharged at a temperature of 100 ℃. As shown in the SEM image, it was confirmed that the operating temperature was different, but the same discharge product was generated after discharge.

Although the exemplary embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.