KR102506439B1 - Positive electrode for metal air battery, metal air battery including the same, and method of preparing the positive electrode for metal air battery - Google Patents

Abstract

Disclosed are a positive electrode for a metal-air battery, a metal-air battery including the same, and a method for manufacturing the positive electrode for a metal-air battery. The positive electrode for the metal-air battery may include a lithium salt; and a carbon-based material including a polymer electrolyte layer composed of a polymer electrolyte comprising at least one hydrophilic material and a hydrophobic material coated on a surface thereof, wherein a portion of the polymer electrolyte is non-covalently bonded to the surface of the carbon-based material. It can be anchored by a covalent bond.

Description

Positive electrode for metal air battery, metal air battery including the same, and method of preparing the positive electrode for metal air battery}

A positive electrode for a metal-air battery, a metal-air battery including the same, and a method for manufacturing the positive electrode for a metal-air battery.

A metal-air battery, for example, a lithium-air battery, generally has a negative electrode capable of intercalating/extracting lithium ions, a positive electrode (air electrode) in which oxygen is used as an active material and oxygen reduction and oxidation reactions occur, and between the negative electrode and the positive electrode. It is known to have a separator.

The theoretical energy density per unit weight of a lithium-air battery is more than 3500 Wh/kg, which is approximately 10 times that of a lithium-ion battery.

A lithium-air battery may generally include an electrolyte in order to secure a delivery path for lithium ions. However, when a lithium-air battery contains an excess amount of electrolyte compared to the carbon-based material of the cathode (air electrode), the energy density per unit weight may be lowered.

In order to solve these problems, there is still a need for a novel anode for a metal-air battery, a metal-air battery including the same, and a method for manufacturing the anode for a metal-air battery.

One aspect is to provide a cathode for a metal-air battery including a carbon-based material including a polymer electrolyte layer composed of a polymer electrolyte including at least one hydrophilic material and a hydrophobic material coated on a surface thereof.

Another aspect is to provide a metal-air battery including the positive electrode.

Another aspect is to provide a manufacturing method of the anode for the metal-air battery.

According to one aspect,

lithium salt; and

A carbon-based material including a polymer electrolyte layer composed of a polymer electrolyte including at least one hydrophilic material and a hydrophobic material coated on a surface thereof,

A positive electrode for a metal-air battery in which a portion of the polymer electrolyte is anchored to a surface of the carbon-based material by a non-covalent bond or a covalent bond is provided:

According to other aspects,

a negative electrode containing lithium or a lithium alloy;

the aforementioned anode; and

A metal-air battery including a separator disposed between the negative electrode and the positive electrode is provided.

According to another aspect,

A method comprising a polymer electrolyte layer composed of a polymer electrolyte containing at least one hydrophilic material and a hydrophobic material coated on the surface of the carbon-based material by adding a carbon-based material, a polymer electrolyte, and a lithium salt to a solvent, dispersing and drying the mixture. There is provided a method for manufacturing a positive electrode for a metal-air battery, including the step of preparing a positive electrode.

A cathode for a metal-air battery according to one aspect includes a carbon-based material including a polymer electrolyte layer composed of a lithium salt and a polymer electrolyte including at least one hydrophilic material and a hydrophobic material coated on a surface of the carbon-based material. Since a part of the polymer electrolyte is fixed to the surface of the polymer electrolyte through a non-covalent bond or a covalent bond, the content of the electrolyte can be minimized. The metal-air battery including the positive electrode for the metal-air battery may improve energy density per unit weight.

1 is a schematic diagram showing an anode structure in which a carbon-based material coated with a polymer electrolyte layer is arranged according to an embodiment.
2 is a schematic diagram showing a manufacturing method of a cathode for a metal-air battery according to an embodiment.
3 is a schematic diagram showing the structure of a lithium-air battery according to an embodiment.
FIG. 4a is a TEM image of a carbon-based material coated with a polymer electrolyte layer prepared in Example 1. FIG.
4b and 4c are TEM images of the carbon-based material coated with the polymer electrolyte layer prepared in Example 2, respectively.
5 is a TGA graph of a polymer electrolyte layer of a carbon-based material coated with a polymer electrolyte layer prepared in Example 1;
6A and 6B are C1s and O1s spectra of XPS analysis of the carbon-based material coated with the polymer electrolyte layer prepared in Example 2, respectively.
7a and 7b are first discharge cycle graphs of the lithium-air battery manufactured in Example 4;

Hereinafter, a cathode for a metal-air battery according to an embodiment of the present invention, a metal-air battery including the same, and a manufacturing method of the anode for a metal-air battery will be described in detail with reference to the accompanying drawings. The following is presented as an example, and the present invention is not limited thereby, and the present invention is only defined by the scope of the claims to be described later.

In this specification, the term "include" is used to indicate that other components may be added or/or intervened, not excluded, unless otherwise stated.

A metal-air battery, for example, a lithium-air battery, may include a negative electrode capable of intercalating/extracting lithium ions, a positive electrode using oxygen as an active material, and an electrolyte capable of delivering lithium ions. A lithium-air battery has attracted attention as a battery with a high theoretical energy density per unit weight because there is no need to store oxygen in the lithium-air battery.

A lithium-air battery may use an aqueous electrolyte and a non-aqueous electrolyte as an electrolyte. However, when an aqueous electrolyte is used as the electrolyte, a lithium-air battery including this may cause severe corrosion due to contact between the lithium anode and the aqueous electrolyte. As a result, many studies have been conducted to use non-aqueous electrolyte as the electrolyte. It is becoming.

As the non-aqueous electrolyte, for example, an ionic liquid or an organic liquid electrolyte may be used. As the organic liquid electrolyte, for example, carbonate, ether, sulfone, DMSO (N, N-dimethlysulfoxide), or DMAC (N, N-dimethlysulfonamide) may be used.

In the case of using a non-aqueous electrolyte as an electrolyte, a reaction mechanism shown in Scheme 1 below may be shown.

<Scheme 1>

4Li + O ₂ ↔ 2Li ₂ O E ^o =2.91V

2Li + O ₂ ↔ Li ₂ O ₂ E ^o =3.10V

During discharge, lithium from the negative electrode meets oxygen introduced from the positive electrode (air electrode) to produce lithium oxide, and oxygen is reduced (oxygen reduction reaction: ORR). In addition, on the contrary, during charging, lithium oxide is reduced and oxygen is oxidized (oxygen evolution reaction: OER). According to Reaction Equation 1, during discharge, Li ₂ O ₂ is deposited in the pores of the positive electrode (air electrode), and the capacity of the lithium-air battery increases as the area of the electrolyte in contact with the positive electrode (air electrode) increases.

The anode (air cathode) may include a carbon-based material having a high specific surface area and a high pore volume. However, due to the high pore volume, a large amount of electrolyte is used. When the amount of the electrolyte is large compared to the carbon-based material, the excess electrolyte occupies the space where the discharge product is to be generated. As a result, the generation of discharge products is prevented, and thus the weight of the metal-air battery may be increased and the energy density per unit weight may be lowered.

A positive electrode for a metal-air battery according to an embodiment includes a lithium salt; and a carbon-based material including a polymer electrolyte layer composed of a polymer electrolyte comprising at least one hydrophilic material and a hydrophobic material coated on a surface thereof, wherein a portion of the polymer electrolyte is non-covalently bonded to the surface of the carbon-based material. It can be anchored by a covalent bond.

In this specification, the concepts of "hydrophilicity" and "hydrophobicity" may be understood as relative concepts.

In this specification, the terms "hydrophilic" and "hydrophobicity" are defined as "hydrophilicity of a material surface" and "hydrophobicity of a material surface". In this specification, "hydrophilic material" and "hydrophobic material" are distinguished based on the wettability of the surface of the material to water. The wettability of a material surface to water can be quantitatively analyzed using the contact angle with water.

The "contact angle with water" means an angle formed when water is in thermodynamic equilibrium on a material surface. For example, the water contact angle can be obtained by dropping a predetermined volume of water on a substrate coated with the material and measuring the tangent angle of a line connecting the contact point of the material surface at the end point where the water droplet and the substrate meet on the substrate. . The water contact angle can be theoretically defined by Young's Equation:

γ _lν cos θ _Y = γ _sν - γ _sl (One)

In (1) above, γ _{lν ,} γ _{sν ,} and γ _sl denotes the liquid-gas phase, solid-gas phase, and solid-liquid interfacial tensions, respectively, and θ _Y is represents the contact angle.

This water contact angle can be measured using a telescope-goniometer, captive bubble method in water, tilting plate method, Wilhelmy balance method, capillary method tube method), static sessile droplet method, or ACCU DYNE TEST ^TM kit, etc., can be directly measured by any measurement method available in the art.

The polymer electrolyte may include a hydrophilic material and a hydrophobic material having a difference in contact angle with water of 5° or more. The water contact angle of the hydrophilic material may be 0° to less than 70°. A water contact angle of the hydrophobic material may be 70° or more.

The water contact angle is very closely related to solubility in water. That is, the higher the solubility in water, the lower the water contact angle, and the lower the solubility in water, the higher the water contact angle. Therefore, the solubility of hydrophilic substances in water is higher than that of hydrophobic substances.

For example, when the hydrophilic material is polyethylene glycol and the molecular weight is 4000 daltons, the solubility in water is excellent at 66% (w/w) at 20°C. In comparison, for example, when the hydrophobic material is polypropylene glycol and the molecular weight is 4000 daltons, it is hardly soluble in water, less than 0.01% (w/w) at 20°C. Because of this, for example, in a polymer composed of polyethylene glycol-polypropylene glycol-polyethylene glycol, the polypropylene glycol block of a hydrophobic material with low solubility is internally and the polyethylene glycol block of a hydrophilic material with high solubility depends on the concentration of the polymer in the aqueous solution. It exists towards the outside.

The non-covalent bond refers to a bond between the surface of the carbon-based material and the polymer electrolyte mainly based on a weak bond. For example, the non-covalent bond is a hydrogen bond, a Van der Waals bond, a charge transfer, a dipole-dipole interaction, or a π electron interaction (π -π stacking interaction). The non-covalent bond may be formed by bonding a polymer electrolyte without inducing defects on the surface of the carbon-based material.

The covalent bond refers to a bond formed by a reaction between a reactive functional group directly attached to the surface of the carbon-based material and a functional group of the polymer electrolyte. For example, the reactive functional group directly attached to the surface of the carbon-based material may be "-COOH", "-COH", or "-OH". For example, the covalent bond may be formed using an oxidation reaction, a halogenation reaction, a cycloaddition reaction, a radical addition reaction, or a thiolation reaction. For example, the covalent bond introduces a reactive functional group such as a carboxy group (-COOH) by an oxidation reaction by acid treatment on the surface of the carbon-based material, and an ethylene oxide block having a side chain such as an amino group (-NH ₂ ) The surface of the carbon-based material is shared between the surface of the carbon-based material and the polymer electrolyte by using a functional group of the polymer electrolyte having (e.g., polyethylene oxide (PEO) -b -polypropylene oxide (PPO) -b -polyethylene oxide (PEO) triblock copolymer). A bond may be formed.

The term “anchored” means that the attached part is attached to the surface of the support and the attached part is fixed. The part that is not attached to the support surface may be movable or fixed.

1 is a schematic diagram showing an anode structure in which a carbon-based material coated with a polymer electrolyte layer is arranged according to an embodiment.

In FIG. 1, the anode has a polymer electrolyte coating layer 2 disposed on the surface of the carbon-based material 1 and a plurality of voids between the plurality of carbon-based materials 1 on which the polymer electrolyte coating layer 2 is disposed. ) represents an arranged structure.

A positive electrode for a metal-air battery according to an embodiment may include a polymer electrolyte coating layer composed of a polymer electrolyte including at least one hydrophilic material and a hydrophobic material on the surface of a carbon-based material, thereby minimizing the electrolyte content. In addition, since a portion of the polymer electrolyte may be fixed to the surface of the carbon-based material through a non-covalent bond or a covalent bond, the polymer electrolyte coating layer may be maintained during repeated charging and discharging of the metal-air battery. As a result, the weight of the metal-air battery can be reduced and the energy density per unit weight can be improved.

A part or all of the hydrophobic material of the polymer electrolyte may be non-covalently fixed to the surface of the carbon-based material. Since the surface of the carbon-based material is hydrophobic, affinity with the hydrophobic material of the polymer electrolyte is high, so that part or all of the hydrophobic material of the polymer electrolyte can be easily fixed on the surface of the carbon-based material.

Some or all of the hydrophobic material of the polymer electrolyte may include a hydrophobic repeating unit or/and a hydrophobic functional group.

The hydrophobic repeating unit is, for example, butyl acrylate, 2-ethylhexyl acrylate, methacrylate, benzyl methacrylate, butyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, 2-ethyl Hexyl Methacrylate, Hexadecyl Methacrylate, Hexyl Methacrylate, Isobutyl Methacrylate, Isopropyl Methacrylate, Methyl Methacrylate, Octadecyl Methacrylate, Tetrahydrofurfuryl Methacrylate, Acrylonitrile , maleic anhydride, styrene, propylene glycol, propylene oxide, butene, 1-decene, dicyclopentadiene, isobutylene, 4-methyl-1-pentene, ethylene, propylene, ethylene adipate, ethylene succinate, ethylene terephthalate , 2-ethyl-1,3-hexanediol sebacate, vinyl acetate, vinyl cinnamate, vinyl stearate, tetrahydrofuran, or copolymers thereof.

The hydrophobic functional group may include, for example, a hydroxy group, a methyl group, a carbonyl group, a carboxy group, an amino group, a phosphate group, or a mercapto group.

The hydrophobic repeating unit or/and hydrophobic functional group may be located on the main chain or/and side chain of the polyelectrolyte.

A part or all of the hydrophobic material of the polymer electrolyte of the polymer electrolyte layer may be adsorbed to the surface of the carbon-based material, for example, through a van der Waals bond. Such adsorption does not require inducing defects on the surface of the carbon-based material, and the surface of the carbon-based material can be functionalized while maintaining the inherent properties of the carbon-based material. Due to this, the lithium ion conductivity of the metal-air battery may be maintained without deterioration.

The polymer electrolyte may include a cross-linked polymer electrolyte. The cross-linked polymer electrolyte may more firmly fix the polymer electrolyte coating layer to the surface of the carbon-based material. Due to this, the content of the electrolyte can be extremely minimized. As a result, the weight of the metal-air battery can be further reduced and the energy density per unit weight can be greatly improved.

The polymer electrolyte of the polymer electrolyte layer may include, for example, a block copolymer composed of a hydrophobic block and a hydrophilic block.

The hydrophobic block is the same as the hydrophobic repeating unit described above.

The hydrophilic block is, for example, ethylene glycol, ethylene oxide, N-isopropylacrylamide, 2-oxazoline, 2-ethyl-2-oxazoline, ethylenimine, sulfopropyl acrylate, 2-hydroxypropyl methacrylic acid rate, vinyl alcohol, vinyl pyrrolidone, or copolymers thereof, and the like.

The hydrophobic block of the block copolymer may be fixed to the surface of the carbon-based material and the hydrophilic block may be disposed facing out of the surface of the carbon-based material. For example, the hydrophobic block of the block copolymer is adsorbed to the surface of the carbon-based material through van der Waals bonds, and the hydrophilic block is disposed toward the outside of the surface of the carbon-based material, thereby enabling easy conduction of lithium ions. This form can be confirmed in Figures 2 and 4b.

For example, the block copolymer includes propylene oxide (or propylene glycol) as an example of the hydrophobic block and ethylene oxide (or ethylene glycol) as an example of the hydrophilic block. This distinction is based on a relative concept as described above.

In the block copolymer, propylene oxide (or propylene glycol), a hydrophobic block, is adsorbed to the surface of the carbon-based material by van der Waals bonds, and ethylene oxide (or ethylene glycol), a hydrophilic block, is directed out of the surface of the carbon-based material, are placed Then, for example, as shown in Scheme 2 below, CH ₂ of ethylene oxide (or ethylene glycol), which is a hydrophilic block, is :CH by UV crosslinking (or thermal crosslinking) using a radical agent such as a UV initiator. Radicals are formed, so that a polymer electrolyte including polyethylene oxide (or polyethylene glycol) crosslinked with neighboring :CH radicals and mostly non-crosslinked polypropylene oxide (or polypropylene glycol) may be formed.

<Scheme 2>

The block copolymer may have two or more polymerized monomer blocks different from each other. For example, the block copolymer may have 2 or 3 polymerized monomer blocks different from each other.

The number average molecular weight (Mn) of the hydrophilic block of the block copolymer may be 500 Daltons to 20,000 Daltons. For example, the number average molecular weight (Mn) of the hydrophilic block of the block copolymer may be 500 Daltons to 18,000 Daltons, for example 500 Daltons to 16,000 Daltons, eg 500 Daltons to 14,000 Daltons, eg 500 Daltons to 12,000 Daltons, eg 500 Daltons to 10,000 Daltons, eg , 500 Daltons to 9,000 Daltons, such as 500 Daltons to 8,000 Daltons, such as 500 Daltons to 7,000 Daltons, such as 500 Daltons to 6,000 Daltons, such as 500 Daltons to 5,000 Daltons, such as 600 Daltons to 5,000 Daltons, such as 700 Daltons ( Daltons) to 5,000 Daltons (Daltons), for example, 800 Daltons (Daltons) to 5,000 Daltons (Daltons). When the number average molecular weight (Mn) of the hydrophilic block of the block copolymer is within the above range, the hydrophilic blocks are dispersed without aggregation, so that the lithium ion conductivity of the metal-air battery including the block copolymer may be improved.

The hydrophilic block may be a polymer block having a lithium ion conductive group on a side chain. The lithium ion conductive group exhibits hydrophilicity. Examples of the lithium ion conductive group in the side chain include -SO ₃ ^- , -COO ^- , -(CF ₃ SO ₂ ) ₂ N ^- (hereinafter referred to as 'TFSI ^-' ), -(FSO ₂ ) ₂ N ^- (hereinafter, referred to as 'FSI ^-' ), -SO ₂ N ^- SO ₂ CF ₃ , -SO ₂ N ^- SO ₂ CF ₂ CF ₃ , -SO ₂ C ₆ H ₄ COO-, -C ₆ H ₃ (SO ₂ NH ₂ )COO ^- , -CH(COO ^- )CH ₂ COO ^- , -C ₆ H ₃ (OH)COO ^- , -C ₆ H ₂ (NO ₂ ) ₂ COO ^- , or -CH ₂ C(CH ₃ ) ₂ COO ^- Can be heard on the back.

The polymer block having a lithium ion conductive group in the side chain may be, for example, a polyacrylate block functionalized with TFSI ^- anion or FSI ^- anion, or a polymethacrylate block functionalized with TFSI ^- anion or FSI ^- anion. In the case of having such a lithium ion conductive group as a side chain, mobility of lithium ions can be easily secured and ion conductivity can be improved.

The block copolymer may be a non-crosslinked or crosslinked block copolymer.

For example, the block copolymer is polyethylene glycol- b -polypropylene glycol diblock copolymer, polyethylene oxide- b -polypropylene oxide diblock copolymer, polystyrene- b -polyethylene glycol diblock copolymer, polystyrene- b- Polyethylene oxide diblock copolymer, polystyrene- b -poly(4-vinylpyridine) diblock copolymer, polystyrene- b -poly(meth)acrylate diblock copolymer, polystyrene- b -TFSI ^- anionic functionalized poly( meth)acrylate diblock copolymer, polystyrene- b -FSI ^- anionic functionalized poly(meth)acrylate diblock copolymer, polyethylene glycol- b -polypropylene glycol- b -polyethylene glycol triblock copolymer, polyethylene oxide - selected from b -polypropylene oxide- b -polyethylene oxide triblock copolymer, polyethylene glycol- b -polystyrene- b -polyethylene glycol triblock copolymer, and polyethylene oxide- b -polystyrene- b -polyethylene oxide triblock copolymer One or more may be included.

For example, the block copolymer is crosslinked polyethylene glycol- b -polypropylene glycol diblock copolymer, crosslinked polyethylene oxide- b -polypropylene oxide diblock copolymer, crosslinked polystyrene- b -polyethylene glycol diblock copolymer Copolymer, Crosslinked Polystyrene- b -Polyethyleneoxide Diblock Copolymer, Crosslinked Polystyrene- b -TFSI ^- Anionically Functionalized Poly(meth)acrylate Diblock Copolymer, Crosslinked Polystyrene- b -FSI ^- Anionically Functionalized Poly(meth)acrylate diblock copolymer, crosslinked polyethylene glycol- b -polypropylene glycol- b -polyethylene glycol triblock copolymer, crosslinked polyethylene oxide- b -polypropylene oxide- b -polyethylene oxide triblock copolymer , crosslinked polyethylene glycol- b -polystyrene- b -polyethylene glycol triblock copolymer, and crosslinked polyethylene oxide- b -polystyrene- b -polyethylene oxide triblock copolymer.

For example, the block copolymer is crosslinked polyethylene glycol- b -polypropylene glycol diblock copolymer, crosslinked polyethylene oxide- b -polypropylene oxide diblock copolymer, crosslinked polystyrene- b -polyethylene glycol diblock copolymer Copolymer , cross-linked polystyrene- b -polyethylene oxide diblock copolymer, cross-linked polyethylene glycol- b -polypropylene glycol- b -polyethylene glycol triblock copolymer, cross-linked polyethylene oxide- b -polypropylene oxide- b -polyethylene oxide triblock copolymer, crosslinked polyethylene glycol- b -polystyrene- b -polyethylene glycol triblock copolymer, and crosslinked polyethylene oxide- b -polystyrene- b -polyethylene oxide triblock copolymer. there is.

The block copolymer may have a number average molecular weight (Mn) of 3,000 Daltons to 60,000 Daltons. For example, the number average molecular weight (Mn) of the block copolymer may be 3,000 Daltons to 55,000 Daltons, for example 3,000 Daltons to 50,000 Daltons, for example 3,000 Daltons to 45,000 Daltons, such as 3,000 Daltons to 40,000 Daltons, such as 3,000 Daltons to 35,000 Daltons, such as 3,000 Daltons to 30,000 Daltons, eg 3,000 Daltons to 25,000 Daltons, eg 3,000 Daltons to 20,000 Daltons, eg 3,000 Daltons to 20,000 Daltons , such as 3,500 Daltons to 20,000 Daltons, such as 4,000 Daltons to 20,000 Daltons, such as 4,500 Daltons to 20,000 Daltons, such as 5,000 Daltons to 20,000 Daltons. When the number average molecular weight (Mn) of the block copolymer is within the above range, the lithium ion conductivity may be improved by maintaining elasticity without increasing crystallinity.

The amount of the polymer electrolyte may be 10 parts by weight to 300 parts by weight based on 100 parts by weight of the carbon-based material. With the content of the polymer electrolyte, the metal-air battery can secure sufficient lithium ion conductivity and improve energy density per unit weight.

The polymer electrolyte layer may have a thickness of 1 nanometer (nm) to 30 nanometers (nm). For example, the polymer electrolyte layer may have a thickness of 1 nanometer (nm) to 28 nanometers (nm), for example, 1 nanometer (nm) to 26 nanometers (nm), for example, 1 nanometer (nm). meter (nm) to 24 nanometers (nm), such as 1 nanometer (nm) to 22 nanometers (nm), such as 1 nanometer (nm) to 20 nanometers (nm), such as 1 nanometers (nm) to 18 nanometers (nm), such as 1 nanometer (nm) to 16 nanometers (nm), such as 1 nanometer (nm) to 14 nanometers (nm), for example 1 nanometer (nm) to 12 nanometers (nm), for example, 1 nanometer (nm) to 10 nanometers (nm). The thickness of the polymer electrolyte layer may improve energy density per unit weight while securing lithium ion conductivity within the above range.

The polymer electrolyte layer may be electrochemically stable in the range of 1.4V to 4.5V charge and discharge voltage with respect to lithium. For example, the polymer electrolyte layer may be electrochemically stable in the range of a charging/discharging voltage of 1.5V to 4.5V with respect to lithium.

The carbon-based material may be a porous carbon structure. A part or all of the carbon-based material may be a porous carbon structure. For example, the porous carbon structure may be mesoporous. The carbon-based material secures a sufficient specific surface area so that electrons can be easily transferred through its surface.

For example, the carbon-based material includes carbon nanotubes, carbon nanoparticles, carbon nanofibers, carbon nanosheets, carbon nanorods, carbon nanobelts, graphene, graphene oxide, carbon aerogels, and inverse opal carbon. ), these mixtures, and these complexes. For example, the carbon-based material may include carbon nanotubes, carbon nanoparticles, and composites thereof. These composites may be, for example, composites in which particles containing carbon nanoparticles are disposed on the surface of carbon nanotubes.

For example, the carbon-based material may be a carbon nanotube. The carbon nanotubes may be single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), rope carbon nanotubes, or combinations thereof.

The carbon-based material may be a single-walled carbon nanotube (SWCNT), a double-walled carbon nanotube (DWCNT), a multi-walled carbon nanotube (MWCNT), or a combination thereof.

The average aspect ratio (average length/average diameter) of the carbon nanotubes may be 1 to 20,000. The average aspect ratio may be measured by a method well known to those skilled in the art, for example, transmission electron microscopy (TEM), high-resolution transmission electron microscope (HR-TEM), SEM, or field-emission scanning (FE-SEM). It can be measured from a microscope photograph or/and measured using a measuring device using dynamic light-scattering. If the average aspect ratio of the carbon nanotube is within the above range, charge is allowed to be rapidly transferred from the surface to the inside.

The content of the carbon-based material may be, for example, 50 parts by weight to 80 parts by weight based on 100 parts by weight of the total positive electrode.

The lithium salt is LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiN(SO ₂ C ₂ F ₅ ) ₂ , Li(CF ₃ SO ₂ ) ₂ N, 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, LiF, LiBr, LiCl, LiOH, LiI and LiB (C ₂ O ₄ ) ₂ (lithium bis(oxalato) borate; LiBOB) may be one or more selected from the group consisting of. However, it is not limited thereto, and it is possible if it can be used as a lithium salt in the art.

The amount of the lithium salt may be 3 parts by weight to 60 parts by weight based on 100 parts by weight of the total positive electrode. Sufficient lithium ion conductivity may be secured within the range of the lithium salt content.

The molar ratio between the polymer electrolyte monomer and lithium ions in the polymer electrolyte layer may be 40:1 to 3:1. For example, the molar ratio between the polymer electrolyte monomer and lithium ions in the polymer electrolyte layer may be 20:1 to 10:1. However, the molar ratio between the polymer electrolyte monomer and lithium ions is not limited within the above range, and any range is possible as long as it can effectively transfer lithium ions and/or electrons during the charging and discharging process of the metal-air battery.

The anode may be an air cathode.

A metal-air battery according to another embodiment may be a lithium-air battery. The lithium-air battery includes a negative electrode including lithium or a lithium alloy; the aforementioned anode; and a separator disposed between the negative electrode and the positive electrode.

3 is a schematic diagram showing the structure of a lithium-air battery 10 according to an embodiment.

As shown in FIG. 3, the lithium-air battery 10 has a positive electrode (air electrode) 15 using oxygen as an active material adjacent to the first current collector 14, and lithium or lithium adjacent to the second current collector 12. A separator 16 is interposed between the negative electrode 13 and the alloy. A lithium ion conductive solid electrolyte film (not shown) may be additionally disposed on one surface of the positive electrode (air electrode) 15 facing the separator 16 .

The first current collector 14 is porous and may also serve as a gas diffusion layer capable of diffusing air. A pressing member 19 through which air can be delivered to the anode (air electrode) is disposed on the first current collector 14 . An insulating resin case 11 is interposed between the anode (air electrode) 15 and the cathode 13 to electrically separate the air electrode and the cathode. Air is supplied through the air inlet 17a and discharged through the air outlet 17b. The lithium-air battery 10 may be housed in a stainless steel reactor.

The positive electrode (air electrode) 15 includes a carbon-based material including a polymer electrolyte layer composed of a lithium salt and a polymer electrolyte composed of at least one hydrophilic material and a hydrophobic material coated on the surface, and is formed on the surface of the carbon-based material. A portion of the polyelectrolyte may be anchored by a non-covalent bond or a covalent bond.

Details of the lithium salt, the polymer electrolyte, the polymer electrolyte layer, the carbon-based material, and the form fixed by non-covalent or covalent bonds are the same as those described above, so the description below is omitted.

The anode (air cathode) 15 may further include an oxygen oxidation/reduction catalyst. The oxygen oxidation/reduction catalyst is, for example, a noble metal-based catalyst such as platinum, gold, silver, palladium, ruthenium, rhodium, and osmium, an oxide-based catalyst such as manganese oxide, iron oxide, cobalt oxide, nickel oxide, or cobalt Organometallic catalysts such as phthalocyanine may be used, but are not necessarily limited thereto, and any catalyst that can be used as an oxidation/reduction catalyst of oxygen in the art is possible.

The positive electrode (air electrode) 15 may additionally include a binder. The binder may include a thermoplastic resin or a thermosetting resin. For example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene-butadiene rubber, tetrafluoroethylene-perfluoroalkylvinyl ether copolymer, vinylidene fluoride-hexa Fluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, vinylidene fluoride-pentafluoro propylene copolymer, propylene-tetrafluoro Ethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethylvinyl ether-tetrafluoroethylene copolymer, or ethylene -Acrylic acid copolymers may be used alone or in combination, but are not necessarily limited thereto, and any that can be used as a binder in the art is possible.

The second current collector 12 is not particularly limited as long as it has conductivity. For example, stainless, nickel, copper, aluminum, iron, titanium, or carbon etc. are mentioned. The shape of the second current collector 12 includes, for example, a foil shape, a plate shape, a mesh or a grid, and the like, and may be, for example, copper foil. The second current collector 12 may be fixed on a case of Teflon 11b.

The negative electrode 13 may include lithium or a lithium alloy. In some cases, the anode 13 may include a lithium intercalation compound. However, it is not necessarily limited to these, and any material that can be used as the negative electrode 13 in the art, including lithium or capable of intercalating and releasing lithium, can be used. Examples of the lithium alloy include an alloy of aluminum, tin, magnesium, indium, calcium, titanium, or vanadium with lithium. Since the negative electrode 13 determines the capacity of the lithium-air battery, it may be, for example, a lithium thin film.

In some cases, the negative electrode 13 may also include a binder. Examples of the binder include polyvinylidene fluoride (PVdF) and polytetrafluoroethylene (PTFE). The content of the binder is not particularly limited, and may be, for example, 30 parts by weight or less based on 100 parts by weight of the total negative electrode, and more specifically, 1 to 10 parts by weight based on 100 parts by weight of the total negative electrode.

The separator 16 is not limited as long as it has a composition that can withstand the range of use of the lithium-air battery 10, and for example, a polymer non-woven fabric such as polypropylene non-woven fabric or polyphenylene sulfide non-woven fabric, polyethylene or polypropylene, etc. Porous films of olefinic resins can be exemplified, and it is also possible to use 2 or more types of these together.

A lithium ion conductive solid electrolyte film may be additionally disposed on the surface of the positive electrode (air electrode) 15 or the negative electrode 13 . For example, the lithium ion conductive solid electrolyte membrane may serve as a protective layer to prevent direct reaction of impurities such as water and oxygen contained in the electrolyte with lithium contained in the negative electrode 13 . Examples of such a lithium ion conductive solid electrolyte membrane include lithium ion conductive glass, lithium ion conductive crystal (ceramic or glass-ceramic), or an inorganic material containing a mixture thereof, but are not necessarily limited thereto. Any solid electrolyte film capable of protecting the positive electrode (air electrode) 15 or the negative electrode 13 can be used as long as it can be used in the art. Meanwhile, when considering chemical stability, the lithium ion conductive solid electrolyte membrane may be an oxide.

For example, as the lithium ion conductive crystal, Li _{1 +x+ y} (Al, Ga) _x (Ti, Ge) _{2 -x} Si _y P _3-y O ₁₂ (provided that 0≤x≤1, 0≤y≤ 1, for example, 0≤x≤0.4, 0<y≤0.6, or 0.1≤x≤0.3, 0.1<y≤0.4). Examples of the lithium ion conductive glass-ceramic include lithium-aluminum-germanium-phosphate (LAGP), lithium-aluminum-titanium-phosphate (LATP), and lithium-aluminum-titanium-silicon-phosphate (LATSP). there is. In addition, the lithium ion conductive solid electrolyte membrane may further include an inorganic solid electrolyte component as needed. Such an inorganic solid electrolyte may include, for example, Cu ₃ N, Li ₃ N, LiPON, and the like. The lithium ion conductive solid electrolyte membrane may be used as a single layer or multilayer membrane.

The lithium air battery 10 may be manufactured as follows, for example.

First, the anode (air cathode) 15 described above; a negative electrode 13 containing lithium or a lithium alloy; and separator 16 are prepared.

Next, a negative electrode 13 is installed on one side of the case, a separator 16 is installed on the negative electrode 13, and a positive electrode (air electrode) having a lithium ion conductive solid electrolyte membrane installed on the side opposite to the negative electrode 13 (air electrode) 15 ) is installed to face the cathode (13). Subsequently, a porous current collector is placed on the positive electrode (air electrode) 15, and the cell is fixed by pressing with a pressing member 19 through which air can be delivered to the positive electrode (air electrode) 15, and the lithium air battery 10 ) is completed.

In some cases, a small amount of liquid electrolyte containing a lithium salt may be injected into a separator installed on an anode during manufacture of the battery. For example, a 1.0 M LiTFSI propylene carbonate electrolyte may be used by impregnating the separator. However, it is not limited thereto and may include a small amount of an aprotic solvent and a lithium salt or an ionic liquid and a lithium salt usable in the art.

For example, the aprotic solvent is propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, di Propyl carbonate, dibutyl carbonate, fluoroethylene carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N- Dimethylformamide, N,N-dimethylacetamide, N,N-dimethylsulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether or mixtures thereof, and the like.

For example, the ionic liquid is diethyldimethyl (2-methoxyethyl) ammonium bis (trifluoromethane sulfonyl) imide (DEME-TFSi, (diethylmethyl (2-methoxyethyl) ammonium bis (trifluoromethane sulfonyl) imide )) can be.

For example, the ionic liquid may be a polymeric ionic liquid. Specific examples of the polymeric ionic liquid include i) ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, and phosphonium-based , sulfonium-based, triazole-based, and at least one cation selected from mixtures thereof, and ii) BF ₄ ^- , PF ₆ ^- , AsF ₆ - , SbF ₆ ^- , AlCl ₄ ^- , HSO ₄ ^- , ClO ₄ ^{- ,} CH ₃ SO ₃ ^- , CF ₃ CO ₂ ^- , (CF ₃ SO ₂ ) ₂ N ^- , Cl ^- , Br ^- , I ^- , BF ₄ ^- , SO ₄ ^- , PF ₆ ^- , ClO ₄ ^- , CF ₃ SO ₃ ^- , CF ₃ CO ₂ ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ )(CF ₃ SO ₂ )N ^- , NO ₃ ^- , Al ₂ Cl ₇ ^- , AsF ₆ ^- , SbF ₆ ^- _, CF ₃ COO ^- , CH ₃ COO ^- , CF ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₃ C ^- , (CF ₃ CF ₂ SO ₂ ) ₂ N ^- _, (CF ₃ ) ₂ PF ₄ ^- , ( CF ₃ ) ₃ PF ₃ ^- , (CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , (CF ₃ ) ₆ P ^- , SF ₅ CF ₂ SO ₃ ^- , SF ₅ CHFCF ₂ SO ₃ ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , (SF ₅ ) ₃ C ^- , (O(CF ₃ ) ₂ C ₂ (CF ₃ ) ₂ O) ₂ PO ^- and ( CF ₃ SO ₂ ) ₂ N ^- may contain a repeating unit containing one or more anions selected from.

The case may be divided into an upper portion contacting the cathode and a lower portion contacting the air electrode, and an insulating resin is interposed between the upper portion and the lower portion to electrically insulate the cathode and the cathode.

An ion conductive polymer electrolyte may not be further included between the negative electrode 13 and the positive electrode (air electrode) 15 . As a result, the total weight of the lithium-air battery may be reduced, and energy density per unit weight may be improved.

The lithium air battery can be used for both a lithium primary battery and a lithium secondary battery. In addition, the shape is not particularly limited, and examples thereof include a coin shape, a button shape, a sheet shape, a laminated shape, a cylindrical shape, a flat shape, and a horn shape. It can also be applied to large batteries used in electric vehicles and the like.

The term "air" used herein is not limited to atmospheric air, and may include a combination of gases containing oxygen or pure oxygen gas. This broad definition of the term “air” can be applied to all applications, such as air cells, air anodes, and the like.

A method of manufacturing a positive electrode for a metal-air battery according to another embodiment includes adding a carbon-based material, a polymer electrolyte, and a lithium salt to a solvent, dispersing and drying the carbon-based material, and at least one hydrophilic material and a hydrophobic coating on the surface of the carbon-based material. Manufacturing the above-described positive electrode including a polymer electrolyte layer composed of a polymer electrolyte made of a material; may include.

Details of the carbon-based material, the polymer electrolyte, and the lithium salt are the same as those described above, and thus the description thereof is omitted.

The solvent is, for example, 1 selected from the group consisting of water, alcohol, acetone, tetrahydrofuran, cyclohexane, carbon tetrachloride, chloroform, methylene chloride, dimethylformamide, dimethylacetamide, dimethylsulfoxide and N-methylpyrrolidone. There may be more than one species.

2 is a schematic diagram showing a manufacturing method of a cathode for a metal-air battery according to an embodiment.

After adding the carbon-based material and the polymer electrolyte to a solvent in an appropriate weight ratio to obtain a mixed solution, a lithium salt is added and dispersed in an appropriate molar ratio of the polymer electrolyte monomer and lithium ions. Thereafter, a filtration process may be performed before drying the dispersion. The filtration process may be a filter filtration process having pores of 1 micrometer (㎛) or less. For the filtration step, for example, a PVdF membrane or the like can be used. Through this process, it is possible to obtain a carbon-based material including a lithium salt and a polymer electrolyte coating layer on the surface.

A crosslinking process may be further included after adding the carbon-based material, the polymer electrolyte, and the lithium salt to a solvent to disperse and dry them.

The crosslinking process may be a thermal crosslinking or UV crosslinking process. If necessary, the thermal crosslinking process may use a crosslinking agent and the UV crosslinking process may use a UV initiator.

As the crosslinking agent, for example, polyhydric alcohols or polyhydric epoxy compounds may be used. Examples of polyhydric alcohols include aliphatic polyhydric alcohols such as ethylene glycol, glycerin, and polyvinyl alcohol, aromatic polyhydric alcohols such as pyrogatechol, resorcinol, and hydroquinone, and examples of polyhydric epoxy compounds include , aliphatic polyvalent epoxy compounds such as glyceryl polyglycidyl ether and trimethylolpropane polyglycidyl ether, or aromatic polyvalent epoxy compounds such as bisphenol A type epoxy compounds can be used. However, the use of any crosslinking agent that can be used in the art is possible without being particularly limited to the examples of the crosslinking agent. The crosslinking density can be easily controlled using a crosslinking agent, and the polymer electrolyte layer can be appropriately anchored on the surface of the carbon-based material.

The content of the crosslinking agent may be, for example, in the range of 1 to 40% by weight based on the total weight of polymer electrolyte polymerization monomers.

As the thermal crosslinking condition, it may be performed for 2 hours to 6 hours at a temperature of about 80 ° C to 120 ° C under the air atmosphere or an oxidizing atmosphere.

The UV initiator is not particularly limited, but may be any material that generates free radicals by receiving ultraviolet rays. The UV initiator may be, for example, a UV initiator having a double bond. UV crosslinking may be performed for 20 to 60 minutes using UV irradiation equipment on the lithium salt and the carbon-based material including the polymer electrolyte coating layer on the surface.

Thereafter, an unreacted crosslinking agent or UV initiator is removed in a vacuum oven to prepare a positive electrode for a metal-air battery.

Examples and comparative examples of the present invention are described below. However, the following examples are merely examples of the present invention and the present invention is not limited to the following examples.

[Example]

Example 1: polymer electrolyte layer Preparation of coated carbon-based materials

50 mg of multi-walled carbon nanotubes (manufactured by Hanwha Chemical, CM250, 92-96%) and polyethylene glycol- b -polypropylene glycol- b -polyethylene glycol triblock copolymer (manufactured by Sigma Aldrich, Pluronic P-123, average Mn: 5800 Daltons, EO: PO: EO = 20:70:20 feed ratio, PEG: 30% by weight) 200 mg of the polymer electrolyte was added to 100 mL of water to obtain a mixed solution.

Lithium trifluoromethanesulfonimide (LiTFSI) powder was added to the mixture so that the molar ratio of EO/Li was 20, and then dispersed for 2 hours using a tip-type ultrasonic disperser. A certain amount of the dispersion was filtered through a Whatman ^® PVdF membrane (pore size: 0.2 μm) to obtain multi-walled carbon nanotubes coated with a polymer electrolyte layer composed of PEG- b -PPG- b- PEG triblock copolymer polymer electrolyte on the surface did

The obtained product was dried at room temperature for 12 hours and in a vacuum oven for 12 hours. Thereafter, the dried product was impregnated with an excess of UV initiator Luperox ^® 104 to perform a UV cross-linking process, and unreacted UV initiator Luperox ^® 104 was removed in a vacuum oven to obtain a PEG- b -PPG- b -PEG tree cross-linked on the surface. A multi-walled carbon nanotube coated with a polymer electrolyte layer composed of a block copolymer polymer electrolyte was prepared.

Example 2: polymer electrolyte layer Preparation of coated carbon-based materials

Polyethylene glycol- b -polypropylene glycol- b -polyethylene glycol triblock copolymer (manufactured by Sigma Aldrich, Pluronic P-123, average Mn: 5800 Daltons, EO: PO: EO=20:70:20 feed ratio, PEG: 30% by weight) Polyethylene glycol- b -polypropylene glycol- b -polyethylene glycol triblock copolymer (manufactured by Sigma Aldrich, Pluronic F-127, average Mn: 12100 Daltons, EO: PO: EO= 101: 56 instead of polymer electrolyte) : 101 feed ratio, PEG: 73.5% by weight) A multi-walled carbon nanotube coated with a polymer electrolyte layer was prepared in the same manner as in Example 1, except that the polymer electrolyte was used.

Example 3: of lithium air battery produce

A separator was placed on the lithium metal thin film negative electrode.

0.1 mL of an electrolyte solution in which 1M LiTFSI (Lithium bis(trifluoromethanesulfonyl)imide) was dissolved in Poly(Ethylene glycol)-dimethylether (manufactured by Sigma Aldrich, polyethylene glycol dimethyl ether, molecular weight: 500 Daltons) was injected into the separator (Celgard 3501).

On the separator, a lithium-aluminum titanium phosphate (LATP) solid electrolyte (thickness of 250 μm, Ohara Corp., Japan) was disposed.

Then, as an anode (air electrode) on top of the LATP solid electrolyte, a multi-walled carbon coated with a polymer electrolyte layer composed of PEG- b- PPG- b -PEG triblock copolymer polymer electrolyte cross-linked on the surface prepared in Example 1 Nanotubes were placed. At this time, based on 100 parts by weight of the total air electrode, the content of the multi-walled carbon nanotubes coated with the polymer electrolyte layer was 90.5 parts by weight and the content of the lithium salt was 9.54 parts by weight.

Subsequently, a gas diffusion layer (SGL Co., 25BC, gas diffusion layer (GDL)) is attached to the top of the anode, a nickel mesh is placed on the gas diffusion film, and a pressing member through which air can be delivered to the anode is formed. A lithium-air battery was manufactured by pressing and fixing the cell.

An exemplary structure of the lithium air battery is shown in FIG. 3 .

Example 4: of lithium air battery produce

Except for using the multi-walled carbon nanotubes coated with the polymer electrolyte layer prepared in Example 2 instead of using the multi-walled carbon nanotubes coated with the polymer electrolyte layer prepared in Example 1 as the anode (air electrode) , A lithium-air battery was manufactured in the same manner as in Example 3.

comparative example One: of lithium air battery produce

(1) Manufacture of anode (air cathode)

On a hot plate, an electrolyte is prepared by mixing polyethylene oxide (average Mn: 100,000 daltons, Aldrich), an ion conductive polymer, and LiTFSI, a lithium salt, so that the molar ratio of EO/Li is 20, and then the electrolyte and multi-walled carbon nanotubes (Hanwha Chemical, CM250, 92-96%) was added to the multi-walled carbon nanotubes so that the weight ratio was 3:1 and mixed again to obtain an anode (air cathode) slurry.

The cathode slurry was coated on a lithium-aluminum titanium phosphate (LATP) solid electrolyte film (thickness 250 μm, Ohara Corp., Japan) with a content of 3.248 mg/cm ² (area of about 1 cm × 1 cm), An anode (air electrode) was prepared.

(2) Fabrication of lithium air battery

Lithium air was prepared in the same manner as in Example 3, except that (1) the anode (air cathode) was used instead of the multi-walled carbon nanotube coated with the polymer electrolyte layer prepared in Example 1 as the anode (air cathode). A battery was made.

analysis example 1: TEM analysis - morphology analyze

TEM analysis was performed on each of the carbon-based materials coated with the polymer electrolyte layer prepared in Examples 1 and 2. For TEM analysis, FEI's Titan Cubed G2 60-300 was used. The results are shown in Figures 4a to 4c, respectively.

4A and 4C are images of carbon-based materials coated with a polymer electrolyte layer prepared in Examples 1 and 2, and FIG. 4B is an image of a carbon-based material coated with a polymer electrolyte layer prepared in Example 2. am.

Referring to FIGS. 4A and 4C, the carbon-based material coated with the polymer electrolyte layer prepared in Examples 1 and 2 has a polymer electrolyte layer having a thickness of about 2 nm and about 5-10 nm, respectively (double-headed arrows). mark) was formed.

Referring to FIG. 4B, in the carbon-based material coated with the polymer electrolyte layer prepared in Example 2, a part of the polymer electrolyte of the polymer electrolyte layer is anchored to the surface by a non-covalent bond or a covalent bond and is cross-linked. can confirm that there is

analysis example 2: TGA analysis - Polyelectrolyte mass loss rate analysis

The polymer electrolyte layer of the carbon-based material coated with the polymer electrolyte layer prepared in Example 1 was subjected to TGA analysis to confirm the polymer electrolyte of the polymer electrolyte layer.

TGA analysis is performed by heating 10 mg of the carbon-based material sample from 0 ° C to 800 ° C at a heating rate of 10 ° C / min under a nitrogen gas atmosphere with a TGA measuring device (Thermal Gravimetric Analysis, TA Instruments, TA Q5000). Weight loss was measured. The results are shown in FIG. 5 .

Referring to FIG. 5 , the mass of the polyelectrolyte began to decrease at about 330 and the mass decrease stopped at about 400. It can be confirmed that the mass reduction rate of the polymer electrolyte is about 45.5%.

analysis example 3: XPS analysis - polymers on the surface of carbon-based materials electrolyte layer analyze

The polymer electrolyte of the polymer electrolyte layer was confirmed by XPS analysis of the carbon-based material coated with the polymer electrolyte layer prepared in Example 2. The results are shown in Figures 6a and 6b.

XPS analysis was performed by using an XPS measuring device (X-ray Photoelectron Spectroscopy, PHI, Versaprobe) on an appropriate amount of the carbon-based material sample.

Referring to FIG. 6A , it can be confirmed that C-O bonds observed in the polymer electrolyte and C-C and C=C bonds observed in the carbon-based material and the polymer electrolyte are observed on the surface of the carbon-based material. After sputtering for 2 minutes, when the surface of the carbon-based material was pulverized and observed, it can be observed that the size of the peak corresponding to the C-O bond decreases.

Referring to Figure 6b, it can be observed that the size of the peak corresponding to the C-O bond decreases after sputtering for 2 minutes. From this, it can be confirmed that the polymer electrolyte exists on the surface of the carbon-based material.

evaluation example One: charge and discharge Characteristic evaluation - Energy density evaluation

After discharging the lithium-air battery manufactured by Example 3 and Comparative Example 1 at 60°C and 1 atm oxygen atmosphere to 2.0 V (vs. Li) with a constant current of 0.048 mA/cm ² , and then charging to 4.3V with the same current , a charge/discharge cycle was performed in which the charge current was charged up to 0.0048 mA/cm ² . Some of the results of the charge/discharge test in the first cycle are shown in Table 1 and FIG. 7A.

In addition, the lithium-air battery manufactured in Example 4 and Comparative Example 1 was discharged to 1.5 V (vs. Li) at a constant current of 0.048 mA/cm ² in an oxygen atmosphere at 60 ° C. and 1 atm, and then charged to 4.0 V at the same current. After that, a charge/discharge cycle was performed in which the charge current was charged up to 0.0048 mA/cm ² . Some of the charge/discharge test results in the first cycle are shown in Table 2 and FIG. 7B.

In the energy density per unit weight, the unit weight is the total weight of the anode (air electrode) including the electrolyte, the carbon-based material (coated with the polymer electrolyte layer), and the discharge product, and the energy is the amount of discharge divided by the average discharge voltage.

carbon weight electrolyte weight discharge amount energy density (mg) (mg) (mAh) (Wh/kg) Example 3 0.40645 0.33255 0.43 190.18 Comparative Example 1 0.406 1.218 0.43 145.81

carbon weight electrolyte weight discharge amount energy density (mg) (mg) (mAh) (Wh/kg) Example 4 1.03 0.499 0.54 237.12 Comparative Example 1 1.03 3.10 0.54 164.97

Referring to Table 1 and FIG. 6A, the energy density of the lithium-air battery manufactured in Example 3 was improved by about 44 Wh/kg compared to Comparative Example 1. Referring to Table 2 and FIG. 6B, the energy density of the lithium-air battery manufactured in Example 4 was improved by about 72 Wh./kg compared to Comparative Example 1. This is due to the decrease in the weight of the electrolyte in the anode (air electrode) of the lithium-air battery.

1: carbon-based material 2: polymer electrolyte coating layer
3: void 10: lithium air battery
Reference Numerals 11: insulating case 12: second current collector 13: negative electrode 14: first current collector
15: anode (air cathode) 16: separator
17a: air inlet 17b: air outlet
19: pressing member

Claims (31)

lithium salt; and
A carbon-based material including a polymer electrolyte layer composed of a polymer electrolyte including at least one hydrophilic material and a hydrophobic material coated on a surface thereof,
A part of the polymer electrolyte is anchored to the surface of the carbon-based material by a non-covalent bond or a covalent bond,
The polymer electrolyte comprises a cross-linked polymer electrolyte, a positive electrode for a metal-air battery. According to claim 1,
The polymer electrolyte includes a hydrophilic material and a hydrophobic material having a difference in contact angle with water of 5 ° or more, a cathode for a metal-air battery. According to claim 2,
A cathode for a metal-air battery, wherein the hydrophilic material has a water contact angle of 0° to less than 70°. According to claim 2,
A cathode for a metal-air battery, wherein the hydrophobic material has a water contact angle of 70 ° or more. According to claim 1,
A positive electrode for a metal-air battery, wherein part or all of the hydrophobic material of the polymer electrolyte is fixed to the surface of the carbon-based material by non-covalent bonds. According to claim 1,
A positive electrode for a metal-air battery, wherein part or all of the hydrophobic material of the polymer electrolyte is adsorbed on the surface of the carbon-based material through van der Waals bonds. delete According to claim 1,
A cathode for a metal-air battery, wherein the polymer electrolyte comprises a block copolymer composed of a hydrophobic block and a hydrophilic block. According to claim 8,
A cathode for a metal-air battery, wherein the hydrophobic block of the block copolymer is fixed to the surface of the carbon-based material and the hydrophilic block is disposed toward the outside of the surface of the carbon-based material. According to claim 8,
The block copolymer has two or more polymerized monomer blocks different from each other, a positive electrode for a metal-air battery. According to claim 8,
The number average molecular weight (Mn) of the hydrophilic block of the block copolymer is 500 Daltons to 20,000 Daltons (Daltons), a cathode for a metal-air battery. According to claim 8,
The hydrophilic block is a polymer block having a lithium ion conductive group in a side chain, a positive electrode for a metal-air battery. According to claim 12,
The polymer block having a lithium ion conductive group in the side chain is a polyacrylate block functionalized with TFSI ^- anion or FSI ^- anion, or a polymethacrylate block functionalized with TFSI ^- anion or FSI ^- anion. According to claim 8,
The block copolymer is polyethylene glycol- b -polypropylene glycol diblock copolymer, polyethylene oxide- b -polypropylene oxide diblock copolymer, polystyrene- b -polyethylene glycol diblock copolymer, polystyrene- b -polyethylene oxide diblock Copolymer, Polystyrene- b -Poly(4-vinylpyridine) Diblock Copolymer, Polystyrene- b -Poly(meth)acrylate Diblock Copolymer, Polystyrene- b -TFSI ^- Anionic Functionalized Poly(meth)acrylate Diblock Copolymer, Polystyrene- b -FSI ^- Anionic Functionalized Poly(meth)acrylate Diblock Copolymer, Polyethylene Glycol- b -Polypropylene Glycol- b -Polyethylene Glycol Triblock Copolymer, Polyethylene Oxide- b -Poly At least one selected from propylene oxide- b -polyethylene oxide triblock copolymer, polyethylene glycol- b -polystyrene- b -polyethylene glycol triblock copolymer, and polyethylene oxide- b -polystyrene- b -polyethylene oxide triblock copolymer A positive electrode for a metal-air battery comprising: According to claim 8,
The block copolymer is crosslinked polyethylene glycol- b -polypropylene glycol diblock copolymer, crosslinked polyethylene oxide- b -polypropylene oxide diblock copolymer, crosslinked polystyrene- b -polyethylene glycol diblock copolymer, crosslinked Polystyrene- b -Polyethyleneoxide Diblock Copolymer, Crosslinked Polystyrene- b -TFSI ^- Anionic Functionalized Poly(meth)acrylate Diblock Copolymer, Crosslinked Polystyrene- b -FSI ^- Anionically Functionalized Poly(meth) Acrylate diblock copolymer, crosslinked polyethylene glycol- b -polypropylene glycol- b -polyethylene glycol triblock copolymer, crosslinked polyethylene oxide- b -polypropylene oxide- b -polyethylene oxide triblock copolymer, crosslinked polyethylene A positive electrode for a metal-air battery comprising at least one selected from glycol -b -polystyrene- b -polyethylene glycol triblock copolymers and crosslinked polyethylene oxide- b -polystyrene- b -polyethylene oxide triblock copolymers. According to claim 8,
The number average molecular weight (Mn) of the block copolymer is 3,000 Daltons (Daltons) to 60,000 Daltons (Daltons), a cathode for a metal-air battery. According to claim 1,
A positive electrode for a metal-air battery, wherein the content of the polymer electrolyte is 10 parts by weight to 300 parts by weight based on 100 parts by weight of the carbon-based material. According to claim 1,
A cathode for a metal-air battery, wherein the polymer electrolyte layer has a thickness of 1 nanometer (nm) to 30 nanometers (nm). According to claim 1,
The positive electrode for a metal-air battery, wherein the polymer electrolyte layer is electrochemically stable in the range of 1.4V to 4.5V charge/discharge voltage for lithium. According to claim 1,
The positive electrode for a metal-air battery, wherein the carbon-based material is a porous carbon structure. According to claim 1,
The carbon-based material includes carbon nanotubes, carbon nanoparticles, carbon nanofibers, carbon nanosheets, carbon nanorods, carbon nanobelts, graphene, graphene oxide, carbon aerogels, inverse opal carbon, and mixtures thereof. , and a positive electrode for a metal-air battery selected from these composites According to claim 1,
A positive electrode for a metal-air battery, wherein the content of the carbon-based material is 50 parts by weight to 80 parts by weight based on 100 parts by weight of the total positive electrode. According to claim 1,
The lithium salt is LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiN(SO ₂ C ₂ F ₅ ) ₂ , Li(CF ₃ SO ₂ ) ₂ N, 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, LiF, LiBr, LiCl, LiOH, LiI and LiB (C ₂ O ₄ ) At least one anode selected from the group consisting of ₂ (lithium bis(oxalato) borate; LiBOB) for a metal-air battery. According to claim 1,
A positive electrode for a metal-air battery, wherein the content of the lithium salt is 30 parts by weight to 60 parts by weight based on 100 parts by weight of the total positive electrode. According to claim 1,
The anode is an anode for a metal-air battery, which is an air cathode. a negative electrode containing lithium or a lithium alloy;
a positive electrode according to any one of claims 1 to 6 and 8 to 25; and
A metal-air battery comprising a; separator disposed between the negative electrode and the positive electrode. A polymer electrolyte layer composed of a polymer electrolyte containing at least one hydrophilic material and a hydrophobic material coated on the surface of the carbon-based material by adding a carbon-based material, a polymer electrolyte, and a lithium salt to a solvent, dispersing and drying the agent. A method for manufacturing a positive electrode for a metal-air battery, comprising: preparing the positive electrode according to any one of claims 1 to 6 and 8 to 25. The method of claim 27,
A method of manufacturing a positive electrode for a metal-air battery, further comprising a filtering step before drying after adding and dispersing the carbon-based material, the polymer electrolyte, and the lithium salt in a solvent. According to claim 28,
The filtration process is a method of manufacturing a positive electrode for a metal-air battery, a filter filtration process having pores of 1 micrometer (㎛) or less. The method of claim 27,
A method of manufacturing a positive electrode for a metal-air battery, further comprising a crosslinking step after adding the carbon-based material, the polymer electrolyte, and the lithium salt to a solvent, dispersing and drying them. 31. The method of claim 30,
The crosslinking process is a thermal crosslinking or UV crosslinking process, a method for manufacturing a positive electrode for a metal-air battery.

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