KR101299666B1 - Electrolyte for lithium air rechargeable battery and lithium air rechargeable battery using the same - Google Patents

Abstract

[화학식 2]

(상기 화학식에서, 치환기의 정의는 명세서에 정의한 바와 같다.)A lithium air battery electrolyte and a lithium air battery including the same, specifically, a compound represented by the following Chemical Formula 1, a compound represented by the following Chemical Formula 2, or a combination thereof; Non-aqueous organic solvent; And it relates to an electrolyte for lithium air battery containing a lithium salt.
[Formula 1]

(2)

(In the above formula, the definition of the substituent is as defined in the specification.)

Description

ELECTROLYTE FOR LITHIUM AIR RECHARGEABLE BATTERY AND LITHIUM AIR RECHARGEABLE BATTERY USING THE SAME

The present invention relates to an electrolyte for a lithium air battery and a lithium air battery including the same.

Due to the rapid development of electronic products and high expectations of high performance electric power sources of consumers, many products with high energy consumption are appearing. However, current fuel cell or battery technologies have not yet met this demand. Recently, lithium ion batteries are considered to be the most widely used secondary batteries and the most likely to be developed. However, lithium ion batteries, despite extensive research, still have many problems to be solved, and various limitations such as relatively low theoretical energy unit density and natural reserves of lithium have been derived. Therefore, there is a need for a next-generation secondary battery capable of reducing manufacturing costs while exhibiting high performance to replace a lithium ion secondary battery.

The most feasible of these is a lithium air secondary battery. Lithium-air secondary batteries use metals as fuels, which can eliminate problems related to the generation and storage of hydrogen, which is a challenge for fuel cells, and attract attention in batteries that can be charged and discharged using oxygen in the air as fuel. As a next generation, it is expected to be the next generation secondary battery that can replace the lithium air battery.

However, in the air electrode of the lithium air secondary battery, lithium peroxide (Li ₂ O ₂ ) which is insoluble in the electrolyte during the discharge process is formed, and this product produces an oxidation reaction that generates lithium and oxygen in the subsequent charging reaction. OER) prevents the smooth from occurring, there is a problem that the charge and discharge characteristics of the battery is reduced.

One embodiment of the present invention provides an electrolyte for a lithium air battery that oxidatively decomposes lithium peroxide (Li ₂ O ₂ ) generated in the cathode, thereby increasing the reversibility of the electrochemical reaction in the cathode.

Another embodiment of the present invention is to provide a lithium air battery excellent in charge and discharge characteristics.

One embodiment of the present invention, a compound represented by the following formula (1), a compound represented by the formula (2) or a combination thereof, a non-aqueous organic solvent and a lithium salt containing an electrolyte for a lithium air battery.

[Formula 1]

(2)

In Chemical Formulas 1 and 2, X is B, Al, Ga or In, R ¹ to R ³ are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 cycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, or A substituted or unsubstituted C6 to C30 heteroaryl group, R ⁴ to R ⁶ are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 cycloalkyl group, a substituted or unsubstituted group A substituted C6 to C30 aryl group, a substituted or unsubstituted C6 to C30 heteroaryl group, or

(3)

In Formula 3, R ⁷ to R ¹⁰ are each independently a hydrogen atom or a halogen atom, R ¹¹ is a substituted or unsubstituted C1 to C20 alkyl group, n is an integer of 1 to 10.

Formula 1 may be a compound represented by the following formula (4).

[Formula 4]

In Formula 4, X is B, Al, Ga or In, and R ¹² to R ²⁶ are each independently a hydrogen atom or a halogen atom.

Formula 2 may be a compound represented by the following formula (5).

[Chemical Formula 5]

In Formula 5, X is B, Al, Ga or In, and R ²⁷ to R ²⁹ are each independently a substituted or unsubstituted C1 to C20 alkyl group or a substituted or unsubstituted C1 to C20 allyl group.

The compound represented by Chemical Formula 1 may be tris (pentafluorophenyl) boron (TPFPB).

The compound represented by Formula 2 may be tris (diethylene glycol methyl ether) boron (DEGMEB) or tris (triethylene glycol methyl ether (TEGMEB).

The compound represented by Chemical Formula 1, the compound represented by Chemical Formula 2, or a combination thereof may be included in an amount of 1 to 50 wt% based on the total amount of the electrolyte.

The non-aqueous organic solvent is ethylene carbonate (EC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), γ-butyrolactone (GBL) glutaronitrile (GN), annionitrile (AN) and combinations thereof.

The non-aqueous organic solvent may be glutaronitrile (GN) or adiponitrile (AN).

The electrolyte may include tris (diethylene glycol methyl ether) boron (DEGMEB) and dimethyl carbonate (DMC) in a volume ratio of 4: 1.

The electrolyte is vinylene carbonate, vinyl ethylene carbonate, monofluoroehtylene carbonate, difluoroehtylene carbonate, succinic anhydride, 1,3 It may further comprise an additive selected from propane sultone and combinations thereof.

The additive may be included in an amount of 1 to 10% by weight based on the total amount of the electrolyte.

Another embodiment of the present invention is the electrolyte described above; Air electrode; Provided is a lithium air battery including a negative electrode and a separator.

The lithium air battery including the lithium air battery electrolyte is excellent in charge and discharge characteristics and life characteristics.

1 shows an initial charge and discharge graph of a lithium air battery according to Examples and Comparative Examples.
2 is a graph showing charge and discharge characteristics of a lithium air battery according to an embodiment.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later. Hereinafter, embodiments of the present invention will be described in more detail. However, it should be understood that the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

&Quot; Aryl group " means a C6 to C30 aryl group, " arylalkyl group " means a C7 to C30 arylalkyl group, and " Alkylene group "means a C1 to C20 alkylene group, and the " alkoxysilylene group " means a C1 to C20 alkoxysilylene group.

As used herein, the term "substituted" means that at least one hydrogen atom of the functional group of the present invention is a halogen atom (F, Cl, Br, or I), a hydroxyl group, a nitro group, a cyano group, = NH, = NR, R is an alkyl group having 1 to 10 carbon atoms), an amino group (-NH2, -NH (R '), -N (R ") A substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C6 to C30 aryl group, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C2 to C30 alkoxy group, Substituted or unsubstituted heteroaryl group having from 3 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having from 3 to 30 carbon atoms, and a substituted or unsubstituted heterocycloalkyl group having from 2 to 30 carbon atoms.

The lithium secondary battery can be classified into a lithium ion battery, a lithium ion polymer battery, and a lithium polymer battery depending on the type of the separator and electrolyte used. The lithium secondary battery can be classified into a cylindrical shape, a square shape, a coin shape, Depending on the size, it can be divided into bulk type and thin type. Since the structure and manufacturing method of these batteries are well known in the art, detailed description thereof will be omitted.

One embodiment of the present invention provides a compound represented by the following formula (1), a compound represented by the following formula (2) or a combination thereof, a non-aqueous organic solvent, and an electrolyte for a lithium air battery comprising a lithium salt.

[Formula 1]

(2)

In Chemical Formulas 1 and 2, X is B, Al, Ga or In, R ¹ to R ³ are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 cycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, or A substituted or unsubstituted C6 to C30 heteroaryl group, R ⁴ to R ⁶ are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 cycloalkyl group, a substituted or unsubstituted group A substituted C6 to C30 aryl group, a substituted or unsubstituted C6 to C30 heteroaryl group, or

(3)

In Formula 3, R ⁷ to R ¹⁰ are each independently a hydrogen atom or a halogen atom, R ¹¹ is a substituted or unsubstituted C1 to C20 alkyl group, n is an integer of 1 to 10.

Compound represented by the formula (1) or a compound represented by the formula (2) is B, Al, And electron deficient elements such as Ga or In. The electron deficient element refers to a compound in which the valence electron shell involved in the covalent bond is not completely filled with electrons, that is, an element in which the valence of the atom does not satisfy the Octet rule. . The compound containing the said electron lack element means the compound containing the said electron lack element as a structural element. The compound containing the electron lack element can easily function as an oxidizing agent for oxidizing other compounds because it easily accepts the surrounding electrons in order to exist in an enthalpy stable state.

In one embodiment, the compound represented by Formula 1 may be represented by the following formula (4).

[Formula 4]

In Formula 4, X is B, Al, Ga or In, and R ¹² to R ²⁶ are each independently a hydrogen atom or a halogen atom.

In another embodiment, the compound represented by Chemical Formula 2 may be represented by the following Chemical Formula 5.

[Chemical Formula 5]

In Formula 5, R ²⁷ to R ²⁹ are each independently a substituted or unsubstituted C1 to C20 alkyl group or a substituted or unsubstituted C1 to C20 allyl group.

The compound represented by Chemical Formula 1 may be tris (pentafluorophenyl) boron (TPFPB) represented by Chemical Formula 6, below.

[Formula 6]

The compound represented by Chemical Formula 2 may be tris (diethylene glycol methyl ether) boron (DEGMEB), which is typically represented by Chemical Formula 7, or tris (triethylene glycol methylether) borane, TEGMEB Can be

 [Formula 7]

The compound represented by Chemical Formula 1 or Chemical Formula 2 oxidizes Li ₂ O ₂ or Li ₂ O generated at the cathode during charging and discharging, thereby promoting oxygen evolution reaction (OER). The mechanism in which the compound represented by Chemical Formula 1 or Chemical Formula 2 acts in the electrolyte is specifically as follows.

During discharge of the lithium air battery, oxygen reacts with lithium in the air electrode to generate Li ₂ O ₂ or Li ₂ O, and this reaction may be represented by the following Equations 1 and 2 below.

(Formula 1): 2 Li + + O 2 + 2e - → Li 2 O 2

(Equation 2): 4 Li + + O 2 + 4e - → 2Li 2 O

If Li ₂ O ₂ or Li ₂ O is continuously generated in the cathode, the area in which the void and oxygen react is reduced, and thus the charge / discharge reversible capacity is reduced, resulting in a decrease in charge and discharge characteristics of the lithium air battery. However, the above formula (I) or an electrolyte containing a compound represented by the following formula (2) is Li ₂ O _2, or by promoting an oxidation reaction of Li ₂ O, Li ₂ O ₂ or the reversible capacity decreased to very easily decompose Li ₂ O Prevent it.

In one embodiment, in a lithium air battery using an electrolyte containing TPFPB, Li ₂ O ₂ or Li ₂ O generated on the surface of the cathode is oxidized and decomposed as shown in Equation 3 below to generate oxygen and electrons.

(Equation _{3): Li 2 O 2 →} 2Li - + 2e - + O 2 (oxygen evolution reation)

These electrons and oxygen can be stabilized in the electrolyte through coordination bonds with TPFPB as follows.

Therefore, in the redox decomposition reaction of Equation 3, the equilibrium reaction is promoted to the right, and the reversible capacity and charge / discharge characteristics of the lithium air battery can be improved.

The compound represented by Chemical Formula 1, the compound represented by Chemical Formula 2, or a combination thereof may be included in an amount of 1 to 50 wt% based on the total amount of the electrolyte. For example, it may be included in 3 to 30% by weight or 5 to 10% by weight. When the numerical range is satisfied, the reversible capacity of the lithium air battery is increased, and the charge and discharge characteristics are remarkably improved.

The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.

As the non-aqueous organic solvent, a carbonate-based, ester-based, ether-based, ketone-based, alcohol-based or aprotic solvent may be used. Examples of the carbonate solvent include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC) EC), propylene carbonate (PC), and butylene carbonate (BC) may be used. As the ester solvent, methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate ,? -butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, and the like can be used. Examples of the ether solvent include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, and tetrahydrofuran. As the ketone solvent, cyclohexanone may be used have. In addition, ethyl alcohol, isopropyl alcohol, and the like may be used as the alcohol solvent, and as the aprotic solvent, R-CN such as glutaronitrile (GN) and adiponitrile (AN) (R is C2 to C20). A linear, branched, or cyclic hydrocarbon group, which may include a double bond aromatic ring or ether bond), amides such as dimethylformamide, and dioxolane such as 1,3-dioxolane And sulfolane may be used.

In one embodiment, the non-aqueous organic solvent may be glutaronitrile (GN) or adiponitrile (AN), and the non-aqueous organic solvent may be used alone or in admixture of one or more.

In addition, the mixing ratio in the case of mixing one or more of the non-aqueous organic solvents can be appropriately adjusted according to the desired battery performance, which can be widely understood by those skilled in the art.

In the case of the carbonate-based solvent, it is preferable to use a mixture of a cyclic carbonate and a chain carbonate. In this case, when the cyclic carbonate and the chain carbonate are mixed in a volume ratio of about 1: 1 to about 1: 9, the performance of the electrolytic solution may be excellent.

The non-aqueous organic solvent may further include the aromatic hydrocarbon-based organic solvent in the carbonate-based solvent. In this case, the carbonate-based solvent and the aromatic hydrocarbon-based organic solvent may be mixed in a volume ratio of about 1: 1 to about 30: 1.

The lithium salt is a substance that is dissolved in the non-aqueous organic solvent, acts as a source of lithium ions in the battery to enable operation of the basic lithium secondary battery, and promotes the movement of lithium ions between the cathode and the cathode. to be. The lithium salt Representative examples are _{LiPF 6, LiBF 4, LiSbF 6} , LiAsF 6, LiC 4 F 9 SO 3, LiClO 4, LiAlO 2, 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, LiI, LiB ( C 2 O 4) 2 ( lithium bis oxalate reyito borate (lithium bis (oxalato) borate; LiBOB) , or in a combination thereof The concentration of the lithium salt is preferably within the range of 0.1 to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity Can exhibit excellent electrolyte performance, and lithium ions can effectively migrate.

The electrolyte may further comprise an additive.

The additive is vinylene carbonate, vinyl ethylene carbonate, monofluoroehtylene carbonate, difluoroehtylene carbonate, succinic anhydride, 1,3 -Propane sultone and combinations thereof.

The additive may be included in an amount of 0.1 to 10 wt% based on the total amount of the electrolyte, based on the total amount of the electrolyte. When the numerical range is satisfied, the lifetime characteristics of the lithium air battery are improved by stabilizing the negative electrode interface.

Another embodiment of the present invention, the above-described electrolyte; Air electrode; Provided is a lithium air battery including a negative electrode and a separator.

The cathode includes a current collector and a cathode layer.

The current collector may be aluminum (Al), nickel (Ni), iron (Fe), titanium (Ti), stainless steel, etc., but is not limited thereto. Examples of the shape of the current collector include a foil shape, a plate shape, a mesh (or grid) shape, a foam (or sponge) shape, and the like, and among these, a foam (or sponge) shape excellent in current collection efficiency may be mentioned. .

The cathode layer may further include at least one of a conductive material, a catalyst, and a binder.

The conductive material is used to impart conductivity to the electrode. Any conductive material may be used as long as it is an electron conductive material without causing chemical change in the battery. Specific examples of the conductive material may include a carbon-based material, a metal powder, a metal fiber, or a combination thereof. The carbonaceous material may have a porous structure and a large specific surface area. Examples of the carbon-based material may include natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, carbon nanotube, or a combination thereof. As the metal powder and the metal fiber, a metal such as copper, nickel, aluminum, or silver may be used. Moreover, you may use together 1 type, or 1 or more types of conductive materials, such as a polyphenylene derivative.

The conductive material may be included in the amount of 5 to 70% by weight, for example, 30 to 50% by weight based on the total amount of the cathode layer. When the conductive material is included in the content range, it is possible to implement a stable lithium air battery during charging and discharging.

The catalyst is supported on the conductive material to help the decomposition of lithium peroxide (Li ₂ O ₂ ) formed on the surface of the cathode, such as tricobalt tetraoxide (Co3O4), manganese dioxide (MnO2), cerium dioxide (CeO2) , Platinum (Pt), gold (Au), silver (Ag), ferric trioxide (Fe2O3), triiron tetraoxide (Fe3O4), nickel monoxide (NiO), copper oxide (CuO), perovskite-based catalyst or A combination of these.

The catalyst may be included in 1 to 40% by weight based on the total amount of the cathode layer. When the catalyst is included in the content range, it is possible to implement a stable lithium air battery at the time of charging and discharging according to the smooth decomposition of the cathode active material.

The binder adheres well to the cathode active material particles and also adheres the cathode active material to the current collector, and specific examples thereof include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, Carboxylated polyvinylchloride, polyvinylfluoride, polymers including ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride and hexafluoropropylene Copolymer polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, and the like, but is not limited thereto.

The binder may be included in an amount of 5 to 30 wt% based on the total amount of the cathode layer. When the binder is included in the content range, it is possible to implement a stable lithium air battery during charging and discharging.

The air electrode is designed by exposing to air when manufacturing a lithium air battery. By exposing the cathode to the air, oxygen generated by the decomposition of the cathode active material may escape to the outside of the battery, thereby preventing oxidation of the electrolyte due to the oxygen generated by the decomposition. In addition, when a small spark occurs, it can be exploded due to oxygen, which can be prevented, and can also prevent the volume expansion of the battery due to oxygen.

The negative electrode includes a current collector and a negative active material layer formed on the current collector, and the negative active material layer includes a negative active material.

The negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, a lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

As a material capable of reversibly intercalating / deintercalating lithium ions, any carbonaceous anode active material commonly used in lithium ion secondary batteries can be used as the carbonaceous material. Typical examples thereof include crystalline carbon , Amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in the form of amorphous, plate-like, flake, spherical or fibrous type. Examples of the amorphous carbon include soft carbon (soft carbon) Or hard carbon, mesophase pitch carbide, fired coke, and the like.

Examples of the lithium metal alloy include lithium and a metal such as Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Alloys may be used.

Examples of a material capable of doping and undoping lithium include Si, SiOx (0 <x <2), and Si-Q alloys (wherein Q is an alkali metal, an alkaline earth metal, a group 13 to 16 element, a transition metal, and a rare earth element). Or a combination thereof, not Si), Sn, SnO 2, Sn-R (wherein R is an alkali metal, an alkaline earth metal, a group 13 to 16 element, a transition metal, a rare earth element, or a combination thereof, and not Sn) These etc. can also be mentioned, Moreover, at least 1 and SiO2 can also be mixed and used. Specific elements of Q and R include Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof is mentioned.

Examples of the transition metal oxide include vanadium oxide, lithium vanadium oxide, and the like.

The negative electrode active material layer also includes a binder, and may optionally further include a conductive material.

The binder serves to adhere the anode active material particles to each other and to adhere the anode active material to the current collector. Typical examples thereof include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, Such as polyvinyl chloride, polyvinyl fluoride, polymers comprising ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, Styrene-butadiene rubber, epoxy resin, nylon, and the like may be used, but the present invention is not limited thereto.

The conductive material is used for imparting conductivity to the electrode. Any material can be used as long as it does not cause any chemical change in the battery. Examples of the conductive material include natural graphite, artificial graphite, carbon black, acetylene black, , Carbon-based materials such as carbon fibers; Metal powders such as copper, nickel, aluminum, and silver, or metal-based materials such as metal fibers; Conductive polymers such as polyphenylene derivatives; Or a mixture thereof may be used.

The current collector may be a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foil, a copper foil, a polymer substrate coated with a conductive metal, or a combination thereof.

The cathode and the cathode are each prepared by mixing an active material, a conductive material and a binder in a solvent to prepare an active material composition, and applying the composition to a current collector. The method of manufacturing the electrode is well known in the art, and therefore, a detailed description thereof will be omitted herein. N-methylpyrrolidone may be used as the solvent, but is not limited thereto.

Depending on the type of lithium secondary battery, a separator may exist between the cathode and the anode. The separator may be polyethylene, polypropylene, polyvinylidene fluoride or a multilayer film of two or more thereof. The separator may be a polyethylene / polypropylene double layer separator, a polyethylene / polypropylene / polyethylene triple layer separator, a polypropylene / It is needless to say that a mixed multilayer film such as a propylene three-layer separator and the like can be used. Glass fibers may also be used.

Hereinafter, examples and comparative examples of the present invention will be described. The following embodiments are only examples of the present invention, and the present invention is not limited to the following embodiments.

Lithium air battery manufacturers

Example

( Air pole  Produce)

Lithium peroxide (Li ₂ O ₂ ) is included in the preparation of the cathode to show the decomposition effect of the produced lithium peroxide, the lithium peroxide (Li ₂ O ₂ ), polyvinylidene fluoride (PVDF) and carbon black (super P) The mixture was mixed at a weight ratio of 40:50:10, and it was dispersed in N-methyl-2-pyrrolidone (NMP) to prepare a cathode slurry. The cathode slurry uniformly mixed was coated on an aluminum current collector and dried at 110 ° C. for 1 hour to prepare an cathode.

(Preparation of negative electrode)

A negative electrode was prepared by laminating a 600 micron-thick foil-type lithium metal onto a copper current collector.

(Manufacture of electrolyte)

Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were dissolved in 1 M LiPF ₆ in a mixed organic solvent in a volume of 3: 7, and fluoro ethylene carbonate (FEC) was added 3% by weight relative to the total amount of electrolyte. Thereafter, tris (pentafluorophenyl) boron (TPFPB) was added to the total amount of the electrolyte by 5% by weight to prepare an electrolyte.

 (Manufacture of lithium air battery)

A 2032 coin full cell type lithium air battery was fabricated by using the above-described pore, negative electrode, and electrolyte and separator of porous polyethylene membrane.

( Comparative Example  )

A lithium air battery was manufactured in the same manner as in Example 1, except that an electrolyte without using tris (triethylene glycol methyl ether (TEGMEB) was used.

Experimental Example  : Of lithium air battery Charging and discharging  Property evaluation

Injecting the coin-full cell prepared in the above Examples and Comparative Examples, the lithium air battery was charged up to 4.0V with respect to the lithium electrode at a constant current condition of 0.03C at room temperature and discharged to 2.0V at 0.03C at constant current. After initial charging and discharging, charging and discharging were performed under the same conditions.

The experimental results are shown in FIGS. 1 and 2.

1 shows an initial charge and discharge graph of a lithium air battery according to Examples and Comparative Examples. As can be seen in Figure 1, in the case of the embodiment, it can be seen that the reduction voltage at which lithium peroxide (Li ₂ O ₂ ) is decomposed as low as 0.6V, compared to the comparative example. This is because overvoltage due to polarization does not occur in the air electrode containing lithium peroxide. This suggests that in a lithium air battery using an electrolyte containing a compound represented by the formula (1) or (2), lithium peroxide formed during charging and discharging can be decomposed at a low charging voltage.

2 is a graph showing charge and discharge characteristics after three cycles of the lithium air battery according to the embodiment. As shown in FIG. 2, the lithium air battery according to the embodiment was found to have excellent charge and discharge characteristics without deterioration in capacity. However, in the lithium air battery according to the comparative example, the lithium peroxide formed on the surface of the cathode was not decomposed, and thus the charge / discharge experiment could not be continued after precycle. This shows that the charge and discharge characteristics of a lithium-air battery using an electrolyte containing tris (pentafluorophenyl) boron (TPFPB) are excellent.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, And falls within the scope of the invention.

Claims (12)

An electrolyte for a lithium air battery comprising a compound represented by Chemical Formula 1, a compound represented by Chemical Formula 2 or a combination thereof, a non-aqueous organic solvent, and a lithium salt;
Air electrode;
cathode; And
A lithium air battery comprising a separator.
[Formula 1]

(2)

(In the above formulas (1) and (2)
X is B, Al, Ga or In,
R ¹ to R ³ are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 cycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C6 to C30 heteroaryl group,
R ⁴ to R ⁶ are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 cycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, a substituted or unsubstituted C6 to C30 heteroaryl group or the following formula (3),
(3)

In Formula 3,
R ⁷ to R ¹⁰ are each independently a hydrogen atom or a halogen atom,
R ¹¹ is a substituted or unsubstituted C1 to C20 alkyl group,
n is an integer from 1 to 10.) The method of claim 1,
Lithium air battery is a compound represented by Formula 1 is represented by the following formula (4).
[Chemical Formula 4]

(In the formula 4,
X is B, Al, Ga or In,
R ¹² to R ²⁶ are each independently a hydrogen atom or a halogen atom.) The method of claim 1,
The lithium air battery of the formula 2 is a compound represented by the following formula (5).
[Chemical Formula 5]

(In the above formula (5)
X is B, Al, Ga or In,
R ²⁷ to R ²⁹ are each independently a substituted or unsubstituted C1 to C20 alkyl group or a substituted or unsubstituted C1 to C20 allyl group.) The method of claim 1,
A lithium air battery, wherein the compound represented by Formula 1 is tris (pentafluorophenyl) boron (TPFPB). The method of claim 1,
The compound represented by the formula (2) is tris (diethylene glycol methyl ether) boron (DEGMEB) or tris (triethylene glycol methyl ether (TEGMEB) lithium battery. The method of claim 1,
The compound represented by the formula (1), the compound represented by the formula (2) or a combination thereof will be included in 1 to 50% by weight based on the total amount of the electrolyte. The method of claim 1,
The non-aqueous organic solvent is ethylene carbonate (EC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), γ-butyrolactone (GBL) A lithium air battery that is at least one selected from glutaronitrile (GN), adiponitrile (AN), and combinations thereof. The method of claim 7, wherein
The non-aqueous organic solvent is glutaronitrile (GN) or adiponitrile (AN). The method of claim 1,
The electrolyte comprises a tris (diethylene glycol methyl ether) boron (DEGMEB) and dimethyl carbonate (DMC) in a volume ratio of 4: 1. The method of claim 1,
The electrolyte is vinylene carbonate, vinyl ethylene carbonate, monofluoroehtylene carbonate, difluoroehtylene carbonate, succinic anhydride, 1,3 A lithium air battery further comprising an additive selected from propane sultone and combinations thereof. The method of claim 10,
The additive is a lithium air battery of 1 to 10% by weight based on the total amount of the electrolyte. delete

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