JP7139002B2 - Air diffusion layer for metal-air battery, manufacturing method thereof, and metal-air battery including the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an air diffusion layer for a metal-air battery, a method for manufacturing the same, and a metal-air battery including the same.

A metal-air battery includes a negative electrode that can store and release ions, and a positive electrode that uses oxygen in the air as an active material. At the positive electrode, reduction and oxidation reactions of oxygen introduced from the outside occur, and at the negative electrode, oxidation and reduction reactions of metal occur, and the chemical energy generated at this time is converted into electrical energy. to extract. For example, the metal-air battery absorbs oxygen during discharge and releases oxygen during charge. In this way, the metal-air battery utilizes oxygen present in the air, so that the energy density of the battery can be greatly improved. For example, the metal-air battery can have an energy density several times higher than existing lithium-ion batteries.

At the same time, when the weight of the gas diffusion layer is reduced, the energy density of the metal-air battery can be additionally improved. In relation to this, porous films made of carbon nanomaterials have been used as gas diffusion layers, but they have the problem of degraded mechanical properties.

The problem to be solved by the present invention is to meet the demand for an air diffusion layer with a novel structure and a metal-air battery including the same.

According to one aspect, a porous layer comprising a plurality of non-transmitting fiber structures and a conductive carbon layer comprising a carbon material, said carbon material disposed along the surface of said fiber structure. A gas diffusion layer for a metal-air battery is provided, comprising:

The fiber structures may have a wavy shape or a linear shape, and air gaps may be formed between the fiber structures without intermediate substances.

The fiber structure includes one or more selected from polymeric resin fibers, cellulose and glass fibers, and the porous layer is a woven fabric, a nonwoven fabric, a mesh, or a fabric in which the plurality of fiber structures are bonded together. Combination shapes can be provided.

The carbon material may include one or more selected from carbon fibers, carbon nanotubes (CNT), and graphene nanoplates (GNP).

The thickness of the conductive carbon layer relative to the average thickness of the fiber structure may be 1% or more and 10% or less.

The carbon material included in the conductive carbon layer may be uniformly distributed along the surface of the fiber structure.

The conductive carbon layer may further include a dispersant for dispersing the carbon material.

The dispersant may be a polymeric surfactant. The polymer dispersant includes polystyrene sulfonate (PSS), poly(4-styrenesulfonic acid), polyvinylpyrrolidone (PVP), polyethylene glycol oleyl ether (Brij), and polyoxyethylene stearyl ether. (polyoxyethylene stearyl ether, Brij), polyoxyethylene nonylphenyl ether (IGEPAL), poly (ethylene glycol) - block - poly (propylene glycol) - block - poly (ethylene glycol) - block-poly (propylene glycol)-block-poly (ethylene glycol, Pluronic), poly (propylene glycol)-block-poly (ethylene glycol)-block-poly (propylene glycol), polyethylene-block-poly (ethylene glycol), polyoxyethylene isooctylcyclohexyl ether (Triton) One of them.

The dispersant may be an organic monomolecular dispersant, and may be one of cetylpyridinium chloride (CPC), cetyltrimethylammonium bromide (CTAB), or cetyltrimethylammonium chloride (CTAC).

An adhesive layer disposed between the fiber structure and the conductive carbon layer may further include an adhesion layer for adhering the conductive carbon layer to the surface of the fiber structure.

The adhesive layer includes polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyaniline (PANI), poly(diallyldimethylammonium chloride) (PDDA), polyethylene oxide (PEO), polyethyleneimine (PEI), polyallylamine chlorate ( PAH), poly(acrylic acid), Nafion (registered trademark) (tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulphonic acid copolymer).

The adhesive layers and the conductive carbon layers may be provided in multiple layers, and the multiple layers of the adhesive layers and the multiple layers of the conductive carbon layers may be alternately arranged with each other.

According to another aspect, a metal air comprising depositing an adhesive layer on a surface of a plurality of non-transmitting fiber structures, and depositing a conductive carbon layer comprising a carbon material on top of the adhesive layer. A method for manufacturing a gas diffusion layer for a battery can be provided.

The method may further include uniformly dispersing the carbon material using a dispersant.

The adhesive layer includes polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyaniline (PANI), poly(diallyldimethylammonium chloride) (PDDA), polyethylene oxide (PEO), polyethyleneimine (PEI), polyallylamine chlorate ( PAH), poly(acrylic acid), Nafion (registered trademark) (tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulphonic acid copolymer).

The dispersant may be a polymeric surfactant. The polymer dispersant includes polystyrene sulfonate (PSS), poly(4-styrenesulfonic acid), polyvinylpyrrolidone (PVP), polyethylene glycol oleyl ether, polyoxyethylene stearyl ether. stearyl ether, polyoxyethylene nonylphenyl ether, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(propylene glycol) ) - block - poly (ethylene glycol), Pluronic), poly (propylene glycol) - block - poly (ethylene glycol) - block - poly (propylene glycol) (poly (propylene glycol) - block - poly (ethylene glycol) - block -poly(propylene glycol), polyethylene-block-poly(ethylene glycol), polyoxyethylene isooctylcyclohexyl ether.

The dispersant may be an organic monomolecular dispersant, and may be one of cetylpyridinium chloride (CPC), cetyltrimethylammonium bromide (CTAB), or cetyltrimethylammonium chloride (CTAC).

The step of applying the adhesive layer and the step of arranging the conductive carbon layer may be repeatedly performed so that the plurality of adhesive layers and the plurality of conductive carbon layers are alternately arranged.

According to another aspect, it comprises a negative electrode comprising a metal, a positive electrode comprising a positive electrode catalyst layer and a metal-air battery gas diffusion layer in contact therewith, and an electrolyte provided between the negative electrode and the positive electrode. A metal-air battery, wherein the gas diffusion layer for the metal-air battery includes a porous layer having a plurality of non-transmitting fiber structures, and a carbon material, the carbon material extending along the surfaces of the fiber structures. A metal-air battery can be provided comprising: a conductive carbon layer disposed thereon.

The gas diffusion layer for a metal-air battery may have a porosity of 70 vol % or more.

1 is a cross-sectional view schematically illustrating a two-dimensional planar cell type metal-air battery according to an embodiment of the present invention; FIG. 1 is a schematic perspective view of a three-dimensional metal-air battery according to an embodiment of the present invention; FIG. 1 is a schematic perspective view of a gas diffusion layer according to one embodiment; FIG. 2B is a schematic enlarged view of the gas diffusion layer illustrated in FIG. 2A; FIG. 1 is a scanning electron microscope (SEM) photograph showing a cross section of a fiber structure to which a conductive carbon layer formed by a layer-by-layer method is attached; FIG. 4 is a schematic perspective view of a gas diffusion layer according to another embodiment; 2D is a schematic enlarged view of the gas diffusion layer illustrated in FIG. 2D; FIG. FIG. 11 is a schematic perspective view of a gas diffusion layer according to yet another embodiment; 2F is a schematic enlarged view of the gas diffusion layer illustrated in FIG. 2F; FIG. FIG. 4 is a diagram for explaining a method of forming a gas diffusion layer using a layered self-assembly method according to one embodiment; FIG. FIG. 4 is a diagram for explaining a method of forming a gas diffusion layer using a layered self-assembly method according to one embodiment; FIG. 1 is a schematic perspective view of a gas diffusion layer manufactured using a layered self-assembly method; FIG. 4B is a schematic enlarged view of the gas diffusion layer illustrated in FIG. 4A; FIG. 4 is a SEM photograph showing the microstructure of a gas diffusion layer formed by a layered self-assembly method. 5B is an enlarged photograph of the gas diffusion layer illustrated in FIG. 5A; 5 is a graph showing the relationship between the surface resistance of a gas diffusion layer manufactured by repeatedly performing a layered self-assembly method and the number of repetitions; 4 is a graph showing the results of measuring the energy density and average voltage obtained during the discharge process;

Hereinafter, a gas diffusion layer for a metal-air battery, a method for manufacturing the same, and a metal-air battery including the same according to an embodiment will be described in detail with reference to the accompanying drawings. The widths and thicknesses of layers and regions illustrated in the accompanying drawings may be exaggerated for clarity of the specification and convenience of explanation. Like reference numbers refer to like components throughout the detailed description. In addition, in this specification, the expression "upper" or "above" may include not only the object directly above in contact, but also the object above in a non-contact state. In this specification, "one side" and "other side" refer to two sides opposite to each other, and "one direction" and "other direction" refer to two directions opposite to each other. Also, as used herein, the term "air" means atmospheric air, a combination of gases containing oxygen, or pure oxygen gas.

FIG. 1A is a cross-sectional view schematically illustrating a metal-air battery 1 in the form of a two-dimensional planar cell according to one embodiment of the present invention. FIG. 1B is a perspective view schematically illustrating a three-dimensional metal-air battery 1 according to one embodiment of the present invention.

Referring to FIG. 1A, a metal-air battery 1 in the form of a two-dimensional planar cell according to an embodiment of the present invention includes, for example, a negative electrode metal layer 11, a negative electrode electrolyte film 12, a positive electrode layer 13, and a gas diffusion layer 100 for a metal-air battery ( hereinafter referred to as a “gas diffusion layer”), and an exterior material 16 surrounding the remaining portion of the metal-air battery 1 except for only the upper surface of the gas diffusion layer 100 .

As an example, the negative electrode metal layer 11 may include lithium (Li) metal and a binder capable of intercalating and deintercalating lithium ions. For example, the anode metal layer 11 may be made of a lithium metal-based alloy or a lithium intercalating compound, in addition to lithium metal. The negative electrode electrolyte layer 12 is disposed between the negative electrode metal layer 11 and the positive electrode layer 13 and may include an electrolyte capable of transferring lithium ions generated in the negative electrode metal layer 11 to the positive electrode layer 13 . The positive electrode layer 13 may include an electrolyte for lithium ion conduction, a catalyst for oxidation and reduction of oxygen, a conductive material and a binder. The gas diffusion layer 100 serves to absorb oxygen in the atmosphere and provide it to the positive electrode layer 13 . Therefore, the gas diffusion layer 100 may have a porous structure so that external oxygen can be smoothly diffused.

In the case of the metal-air battery 1 having the two-dimensional planar cell type, if a large number of cells are vertically stacked, it is difficult to supply oxygen to the underlying cells. In addition, the negative electrode metal layer 11 and the negative electrode electrolyte film 12 contribute to the energy density because the weight specific gravity of the current collector (not shown) for extracting current is considerably large in the total weight of the metal-air battery 1 . and the specific gravity of the combined weight of the positive electrode layer 13 becomes smaller. 1B, a three-dimensional metal-air battery 1 according to an embodiment of the present invention may include a cathode layer 13, an anode electrolyte layer 12, an anode metal layer 11, and a gas diffusion layer 100. As shown in FIG.

The gas diffusion layer 100 according to one example may include a first surface Sa, a second surface Sb facing the first surface Sa, and one side surface Sc exposed to the outside.

The positive electrode layer 13, the negative electrode electrolyte film 12 and the negative electrode metal layer 11 are folded at least once so that the positive electrode layer 13 is in contact with the first surface Sa and the second surface Sb of the gas diffusion layer 100, forming the gas diffusion layer. 100 is inserted between the folded positive electrode layers 13 . For example, when the positive electrode layer 13, the negative electrode electrolyte film 12, and the negative electrode metal layer 11 are folded more than once, they are folded in one direction and then folded in the other direction, as shown in FIG. 1B. are folded on each other in such a way that

The positive electrode layer 13, the negative electrode electrolyte film 12, and the negative electrode metal layer 11 are each folded to have a constant width in the thickness direction. As used herein, the "width" and "length" of a component are distinguished by size, with the "width" being shorter than the "length."

As described above, in the structure in which the positive electrode layer 13 is arranged on the first surface Sa and the second surface Sb of the gas diffusion layer 100, the first surface Sa and the second surface Sb of the gas diffusion layer 100 are not exposed to the outside. The air supply to the gas diffusion layer 100 is thereby effected by the sides of the gas diffusion layer 100 or part of said sides. That is, air is supplied to the gas diffusion layer 100 by at least one side surface Sc.

The metal-air battery 1 may have a structure in which the gas diffusion layer 100 has an exposed side surface to smoothly supply air. In addition, even though not shown in the drawings, an exterior material (not shown) is formed on the negative electrode metal layer 11, the negative electrode electrolyte film 12, the positive electrode layer 13, and the gas, except for the exposed side surface Sc of the gas diffusion layer 100. The remaining outer surface of the diffusion layer 100 can be wrapped.

The gas diffusion layer 100 as described above should have electrical conductivity, gas diffusion, and mechanical strength. In the prior art, a porous film made of carbon nanomaterials with excellent electrical conductivity is used as the gas diffusion layer 100. However, in order to improve porosity, a porous three-dimensional structure is used. In the case of forming the , there arises a problem that the resistance of the structure is increased and the mechanical strength is lowered.

In the present disclosure, a porous layer 110 (FIG. 2A) comprising a plurality of non-transmitting fiber structures 111 (FIG. 2A) and a surface of the fiber structures 111 provided in the porous layer 110, e.g. A gas diffusion layer 100 is introduced that includes a conductive carbon layer 120 that is a conformal layer that conforms to the contour, providing electrical conductivity and gas diffusion while providing a certain level of mechanical strength and It is possible to provide the metal-air battery 1 that can achieve weight reduction. Hereinafter, the gas diffusion layer according to one embodiment will be described in more detail.

FIG. 2A is a schematic perspective view of a gas diffusion layer according to one embodiment. FIG. 2B is a schematic enlarged view of the gas diffusion layer illustrated in FIG. 2A. FIG. 2C is a scanning electron microscope (SEM) photograph showing a cross section of a fiber structure to which a conductive carbon layer formed by a layer-by-layer method is attached. FIG. 2D is a schematic perspective view of a gas diffusion layer according to another embodiment; FIG. 2E is a schematic enlarged view of the gas diffusion layer illustrated in FIG. 2D. FIG. 2F is a schematic perspective view of a gas diffusion layer according to yet another embodiment; FIG. 2G is a schematic enlarged view of the gas diffusion layer illustrated in FIG. 2F.

Referring to FIGS. 2A to 2C, the gas diffusion layer 100 according to one embodiment is attached to the surface of a porous layer 110 having pores through which air is diffused and a fiber structure 111 provided in the porous layer 110 . and a conductive carbon layer 120 .

A porous layer 110 according to one example may include a plurality of fiber structures 111 . As an example, the plurality of fiber structures 111 can have a wavy shape or a straight shape. Thereby, air gaps are formed between the fiber structures 111 without an intermediate material, and pores through which the air diffuses are formed in said air gaps. Porous layer 110 may also be embodied by a woven fabric, non-woven fabric, mesh, or a combination thereof in which a plurality of fiber structures 111 are bonded together. The fiber structure 111 can also be non-transmitting so that the porous layer 110 can also be electrically non-transmitting.

As an example, the fiber structure 111 may include one or more selected from polymeric resin fibers, cellulose and glass fibers. For example, the fiber structures 111 may each independently include one or more polymers selected from homopolymers, block copolymers, and random copolymers. For example, fiber structures 111 may each independently be polyethylene, polypropylene, polyethylene terephthalate, polyphenylene sulfide, poly(2-vinylpyridine), polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, polychlorotriethylene. Fluoroethylene, perfluoroalkoxy copolymers, fluorinated cyclic ethers, polyethylene oxide diacrylate, polyethylene oxide dimethacrylate, polypropylene oxide diacrylate, polypropylene oxide dimethacrylate, polymethylene oxide diacrylate, polymethylene oxide dimethacrylate, poly Alkyldiol diacrylate, polyalkyldiol dimethacrylate, polydivinylbenzene, polyether, polycarbonate, polyamide, polyester, polyvinyl chloride, polyimide, polycarboxylic acid, polysulfonic acid, polyvinyl alcohol, polysulfone, polystyrene, polyethylene, polypropylene, poly( p-phenylene), polyacetylene, poly(p-phenylenevinylene), polyaniline, polypyrrole, polythiophene, poly(2,5-ethylenevinylene), polyacene, poly(naphthalene-2,6-diyl), polyethylene oxide, polypropylene oxide, polyvinylidene fluoride, copolymers of vinylidene fluoride and hexafluoropropylene, poly(vinyl acetate), poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate), poly(methyl methacrylate-co-ethyl acrylate), polyacrylonitrile, polyvinyl chloride-co-vinyl acetate, poly(1-vinylpyrrolidone-co-vinyl acetate), polyvinylpyrrolidone, polyacrylate, polymethacrylate, polyurethane, polyvinyl ether, acrylonitrile-butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene- of the group consisting of styrene rubbers, sulfonated styrene/ethylene-butylene triblock copolymers, ethoxylated neopentyl glycol diacrylates, ethoxylated bisphenol A diacrylates, ethoxylated aliphatic urethane acrylates, ethoxylated alkylphenol acrylates and alkyl acrylates Polymers obtained from one or more acrylate monomers selected from, polyvinyl alcohol, polyimide, epoxy resin , acrylics, or combinations thereof.

As an example, the non-woven fabric provided in the porous layer 110 is filtered, for example, by using a paper machine to filter the main material fibers and binder fibers dispersed in water into a form such as a circular mesh or a fourdrinier mesh. Manufactured by drying the resulting product in a dryer. Also, in order to remove fluff from the nonwoven fabric and improve the mechanical properties of the nonwoven fabric, the nonwoven fabric is sandwiched between two rolls and subjected to high pressure heat treatment.

Conductive carbon layer 120 according to one example may include any carbon material having conductivity. As an example, the conductive carbon layer 120 may include one or more carbon materials selected from carbon fibers, carbon nanotubes (CNT), graphene nanoplates (GNP), and carbon-polymer composites. For example, the carbon/polymer composite is also a composite in which a binder is included in the aforementioned carbon fiber, carbon nanotube (CNT), or graphene nanoplate (GNP). By way of example, the binders include vinylidene fluoride/hexafluoropropylene (VDF/HFP) copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polymethylmethacrylate (PMMA) and polytetrafluoroethylene (PTFE), poly Also one or more of acrylonitrile-acrylic acid (PAN/PAA) copolymer, polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), hydroxypropyl cellulose. However, the present disclosure is not limited thereto, and the conductive carbon layer 120 may include any carbon material having conductivity.

Also, the carbon material included in the conductive carbon layer 120 according to one example is disposed along the surface of the fiber structure 111 provided in the porous layer 110 . Thereby, the conductive carbon layer 120 is arranged to cover the surface of the fiber structure 111 . For example, the carbon material contained in the conductive carbon layer 120 is uniformly dispersed by adding a dispersing agent or performing a sonication process, thereby making the conductive carbon layer 120 The included carbon material is evenly distributed along the surface of the fiber structure 111 .

For example, the dispersant may be a polymeric surfactant. For example, the polymeric dispersant is polystyrene sulfonate (PSS), poly(4-styrenesulfonic acid), polyvinylpyrrolidone (PVP), polyethylene glycol oleyl ether (Brij®). , polyoxyethylene stearyl ether, Brij (registered trademark), polyoxyethylene nonylphenyl ether, IGEPAL (registered trademark), poly (ethylene glycol)-block-poly (propylene glycol)- block-poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), Pluronic), poly(propylene glycol)-block-poly(ethylene glycol)-block-poly (propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol), polyethylene-block-poly(ethylene glycol), poly It is also one of polyoxyethylene isooctylcyclohexyl ether (Triton®). The dispersant may also be an organic monomolecular dispersant. For example, the dispersant is also one of cetylpyridinium chloride (CPC), cetyltrimethylammonium bromide (CTAB) or cetyltrimethylammonium chloride (CTAC).

Also, the ultrasonic dispersion process can be performed for several minutes to several hours using, for example, a bar-type sonicator. Also, an ultrasonic dispersing process can be performed while using the dispersing agent. Through this, a solution in which the graphene-based carbon material is dispersed can be produced, and the carbon material is evenly distributed along the surface of the fiber structure 111 by gas diffusion using the dispersion solution. A layer 100 can be formed.

As described above, when the conductive carbon layer 120 is arranged to cover the surface of the fiber structure 111, the thickness of the conductive carbon layer 120 relative to the thickness of the fiber structure 111 is 1% or more and 10% or less. There may be. For example, if the cross-section of the fiber structure 111 is circular, the cross-sectional diameter of the fiber structure 111 may be between 7 μm and 10 μm. The thickness T2 of the carbon layer 120 may range from 100 nm to 1 μm.

In addition, the gas diffusion layer 100 according to one embodiment has a thickness of 50 μm or less, such as 10 to 50 μm, and a weight per unit area of 2 mg/cm ² or less, such as 0.1 to 1.5 mg/cm ² . may be The gas diffusion layer 100 also has a porosity of about 70 vol % or more or about 80 vol % or more, and an electric conductivity of 200 S/m or more.

Also, as described above, the gas diffusion layer 100 according to one embodiment may include, as a support, a porous layer 110 having a porous structure formed by bonding fiber structures 111, thereby reducing weight. And excellent mechanical strength can be secured. In addition, the gas diffusion layer 100 according to one embodiment may include a conductive carbon layer 120 having electrical conductivity on the surface of the fiber structure 111 included in the porous layer 110, thereby increasing the cathode specific capacity. and can meet the requirements of excellent electrical conductivity.

An exemplary metal layer 140 is also disposed along the surface of the conductive carbon layer 120, as illustrated in FIGS. 2D and 2E. For example, the metal material included in the metal layer 140 may be disposed on the conductive carbon layer 120 to improve electrical conductivity of the gas diffusion layer 100 . For example, metal layer 140 may be gold (Au), platinum (Pt), silver (Ag), nickel (Ni), aluminum (Al), iron (Fe), titanium (Ti), copper (Cu), or any of these. It may also include combinations.

An exemplary conductive polymer layer 150 is also disposed along the surface of the conductive carbon layer 120, as illustrated in FIGS. 2F and 2G. For example, a conductive polymer material included in the conductive polymer layer 150 may be disposed on the conductive carbon layer 120 to improve electrical conductivity of the gas diffusion layer 100 . Moreover, since the weight is relatively light as compared with the metal layer 140 described above, the weight of the gas diffusion layer 100 can be reduced. For example, the conductive polymer layer 150 may include polypyrrole (PPy), polythiophene (PT), polyaniline (PAN), or combinations thereof.

3A and 3B are diagrams illustrating a method of forming a gas diffusion layer according to one embodiment using a layered self-assembly method.

Referring to FIG. 3A, an adhesive layer 130 can be placed on the surface of the fiber structure 111 within a given container C1. As an example, an adhesive solution C2 produced by dissolving an adhesive substance in a solvent is placed in a predetermined container C1. can be attached to the surface of For example, the adhesive material can be polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyaniline (PANI), poly(diallyldimethylammonium chloride) (PDDA), polyethylene oxide (PEO), polyethyleneimine (PEI), polyallylamine chloride At least one of acid (PAH), poly(acrylic acid), Nafion® (tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer) As an example, when the fiber structure 111 is put into the adhesive solution C2 in which polyvinyl alcohol (PVA) is dissolved, the non-covalent bond between the fiber structure 111 and polyvinyl alcohol (PVA), which is an adhesive substance, Thus, an adhesive layer 130 is formed on the surface of the fiber structure 111 .

Referring to FIG. 3B, a conductive carbon layer 120 can be placed on the surface of the adhesive layer 130 attached to the surface of the fiber structure 111 in a given container C3. As an example, a dispersion solution C4 in which a carbon material is dispersed in a predetermined solvent can be prepared in a predetermined container C3. For example, the dispersing solution C4 in which the carbon material is dispersed in the solvent may be prepared using the above-described dispersing agent or an ultrasonic dispersing process. As an example, when poly(4-styrenesulfonic acid) is used as the dispersant, the sulfone group (—SO ₃ H) of polystyrene sulfonate (PSS) and the hydroxy group (— OH) allows the conductive carbon layer 120 to adhere to the surface of the adhesion layer 130 .

3A and 3B, the fiber structure 111 and the adhesive layer 130 are combined on the surface of the fiber structure 111 to sequentially bond two ultra-thin layers, namely, the adhesive layer 130 and the conductive carbon layer 120. Between and between the adhesion layer 130 and the conductive carbon layer 120, a bonding scheme such as non-covalent bonding or hydrogen bonding is used, which is called layered self-assembly. By such a method, in the gas diffusion layer 100, the bonding between the fiber structure 111 and the adhesive layer 130 and the bonding between the adhesive layer 130 and the conductive carbon layer 120 are structurally very stable, and the bonding surface area is large. A stable multi-layered ultra-thin film can be realized regardless of the thickness. Therefore, when using this method, the gas diffusion layer 100 in which the surface of the fiber structure 111 is coated with the conductive carbon layer 120 can be easily formed. However, the present disclosure is not limited to the manufacturing method described above, and uses other manufacturing methods to form the gas diffusion layer 100 with the conductive carbon layer 120 coated on the surface of the fiber structure 111. can also

FIG. 4A is a schematic perspective view of a gas diffusion layer manufactured using a layer-by-layer method. FIG. 4B is a schematic enlarged view of the gas diffusion layer illustrated in FIG. 4A. FIG. 5A is a SEM (scanning electron microscope) photograph showing the microstructure of the gas diffusion layer formed by the layered self-assembly method. FIG. 5B is an enlarged photograph of the gas diffusion layer illustrated in FIG. 5A. FIG. 6 is a graph showing the relationship between the surface resistance of the gas diffusion layer manufactured by repeatedly performing the layered self-assembly method and the number of repetitions. FIG. 7 is a graph showing the relationship between the discharge capacity (mAh) value obtained during the discharge process and the cell voltage (V).

4A to 5B, a gas diffusion layer 100 formed using a layered self-assembly method according to one embodiment includes a porous layer 110 having pores through which air is diffused, and a porous layer 110 having pores. A conductive carbon layer 120 including a carbon material, such as carbon nanotubes (CNTs), attached to the surface of the fiber structure 111 and disposed between the porous layer 110 and the conductive carbon layer 120 to form the fiber structure 111. may include an adhesion layer 130 that adheres the surface of the substrate to the conductive carbon layer 120 . The configuration of the porous layer 110, the conductive carbon layer 120 and the adhesive layer 130, the bonding relationship between the fiber structure 111 and the adhesive layer 130, and the bonding relationship between the adhesive layer 130 and the conductive carbon layer 120 are the same as those in the previous embodiments. For convenience of explanation, the description is omitted here.

According to one embodiment, forming the adhesive layer 130 and the conductive carbon layer 120 using a layered self-assembly method is performed iteratively, whereby a plurality of adhesive layers 130 and a plurality of conductive carbon layers 120 are formed. are arranged alternately. Referring to FIG. 6, carbon materials included in the conductive carbon layer 120 include graphene nanoplates (GNP) with a content of 1 mg/ml, carbon nanotubes (CNT) with a content of 1 mg/ml, and carbon nanotubes (CNT) with a content of 3 mg/ml. of carbon nanotubes (CNT) is used and the layered self-assembly process is performed 5 to 20 times, the change in the measured surface resistance of the gas diffusion layer 100 can be confirmed. Regardless of the type and content of the carbon material, when the conductive carbon layer 120 is repeatedly formed by the layered self-assembly method, it can be confirmed that the electrical properties, that is, the surface resistance is reduced. Therefore, the manufacturing times of the conductive carbon layer 120 by layered self-assembly are determined by the mechanical and electrical properties of the gas diffusion layer 100 .

Hereinafter, the present invention will be described with reference to the following examples, but the present invention is not limited only to the following examples.

(Production of gas diffusion layer)
Examples and Comparative Examples: Fabrication of Lithium Air Battery
(Example 1)
A 3 mg/ml carbon nanotube (CM-250, Hanwha chemical) water dispersion was prepared for carbon coating. For smooth dispersion, polystyrene sulfonic acid (Aldrich, Mw=75,000) was added as a dispersant such that the weight ratio of carbon and dispersant was 1:5. A 0.25 wt % aqueous solution of polyvinyl alcohol (Aldrich, Mw=89,000) was used as the adhesive layer polymer.

A layered self-assembly method was used to fabricate carbon-coated gas diffusion layers. PET non-woven fabric (05TH-08, HIROSE) is soaked in PVA aqueous solution, washed with distilled water and dried, then soaked in carbon dispersion, washed with distilled water and dried, one layer of carbon coating formed a layer. It was repeated several times to produce a gas diffusion layer with a certain level of conductivity.

(Comparative example)
Commercial carbon paper (Sigracet 25BA, SGL Group) was used as gas diffusion layer.

(Production of positive electrode)
Carbon nanotubes (NC2100, Nanocyl) as cathode catalyst, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide doped with 0.5 M lithium bis(trifluoromethylsulfonyl)imide as cathode electrolyte (Aldrich ), using polytetrafluoroethylene (PTFE, DAIKIN) as a binder, and mixing them in a weight ratio of 1:2:0.2 to fabricate a positive electrode.

(Fabrication of electrolyte membrane)
N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (KANTO), poly(diallyldimethylammonium bis(trifluoromethanesulfonyl)imide), lithium bis(trifluoromethylsulfonyl)imide, 75:17. A polyethylene (PE) separation membrane (Entek EPX) was impregnated with the solution, which was mixed at a weight ratio of 6:7.4 and diluted with acetonitrile, and dried to prepare an electrolyte membrane.

(Production of lithium-air batteries)
A lithium-air battery was manufactured by sequentially stacking the electrolyte membrane, the positive electrode, and the gas diffusion layer prepared above on the lithium foil negative electrode.

Evaluation Example: Evaluation of Discharge Characteristics and Energy Density Discharge (full discharge) and charge were performed at 80° C. in an oxygen atmosphere at a current density of 0.24 mA/cm ² . The discharge capacity (mAh) value and average voltage (V) obtained during the discharge process were measured, and the results are shown in FIG. The energy densities of the examples and the comparative examples can be evaluated based on the discharge characteristic evaluation results.

Referring to Table 1, it can be seen that the lithium-air batteries manufactured in Examples have higher energy densities than the lithium-air batteries manufactured in Comparative Examples.

(Example 2)
A gas diffusion layer was fabricated by additionally coating polypyrrole (PPy) on the carbon coating layer fabricated using the layered self-assembly method according to Example 1. The nonwoven fabric coated with the conductive carbon layer manufactured by the layered self-assembly method was dipped in a 5 wt% polypyrrole aqueous solution (Aldrich, 482552), dipped for 10 minutes, and dried to obtain a highly conductive material. A gas diffusion layer comprising a molecular layer was fabricated.

(Example 3)
A gas diffusion layer was fabricated by additionally coating gold on the carbon coating layer fabricated using the layered self-assembly method according to Example 1. FIG. A gas diffusion layer having a metal layer was manufactured by coating the non-woven fabric coated with the conductive carbon layer manufactured by the layered self-assembly method with gold using a sputtering method.

Referring to Table 2, it was found that the lithium-air batteries manufactured in Examples 2 and 3 had lower sheet resistance than the lithium-air battery manufactured in Example 1.

According to an embodiment of the present disclosure, a metal-air battery with high capacity and high energy density can be implemented. A metal-air battery with a composite laminate structure, such as a three-dimensional folding cell, can be implemented. A metal-air battery that maintains electrical conductivity and porosity and is advantageous in terms of mechanical strength and weight reduction can be implemented.

Although preferred embodiments of the present invention have been described with reference to the drawings and examples, they are merely exemplary, and many variations thereof will occur to those skilled in the art. , and that other equivalent implementations are possible. Therefore, the protection scope of the present invention is defined by the claims.

INDUSTRIAL APPLICABILITY The air diffusion layer for a metal-air battery, the method for manufacturing the same, and the metal-air battery including the same according to the present invention can be effectively applied to, for example, battery-related technical fields.

Reference Signs List 1 metal-air battery 11 negative electrode metal layer 12 negative electrode electrolyte membrane 13 positive electrode layer 16 exterior material 100 gas diffusion layer 110 porous layer 111 fiber structure 120 conductive carbon layer 130 adhesive layer

Claims (20)

a porous layer comprising a plurality of non-transmitting fiber structures;
a conductive carbon layer comprising a carbon material, said carbon material disposed along a surface of said fiber structure;
an adhesion layer disposed between the fiber structure and the conductive carbon layer to adhere the conductive carbon layer to the surface of the fiber structure ;
The metal-air battery , wherein the adhesive layers and the conductive carbon layers are provided in a plurality of layers, and the adhesive layers of the plurality of layers and the conductive carbon layers of the plurality of layers are alternately arranged. gas diffusion layer. The gas diffusion for metal-air battery according to claim 1, wherein the fiber structure has a wavy shape or a linear shape, and an air gap is formed between the fiber structures without an intermediate material. layer. The fiber structure includes one or more selected from polymeric resin fibers, cellulose and glass fibers, and the porous layer is a woven fabric, a nonwoven fabric, a mesh, or a fabric in which the plurality of fiber structures are bonded together. 3. The gas diffusion layer for a metal-air battery according to claim 1, wherein the gas diffusion layer has a combined shape. 4. The carbon material according to any one of claims 1 to 3, wherein the carbon material includes one or more selected from carbon fibers, carbon nanotubes (CNT), graphene nanoplates (GNP), and carbon/polymer composites. 2. The gas diffusion layer for a metal-air battery according to item 1. The gas for a metal-air battery according to any one of claims 1 to 4, wherein the thickness of the conductive carbon layer relative to the average thickness of the fiber structure is 1% or more and 10% or less. diffusion layer. The metal-air battery according to any one of claims 1 to 5, wherein the carbon material contained in the conductive carbon layer is uniformly distributed along the surface of the fiber structure. gas diffusion layer. The gas diffusion layer of claim 6, wherein the conductive carbon layer further comprises a dispersant for dispersing the carbon material. The dispersant includes polystyrene sulfonate (PSS), polystyrene sulfonic acid, polyvinylpyrrolidone (PVP), polyethylene glycol oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene nonylphenyl ether, poly(ethylene glycol)-block-poly(propylene). glycol)-block-poly(ethylene glycol) (Pluronic), poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol), polyethylene-block-poly(ethylene glycol), polyoxyethylene iso 8. The method according to claim 7, characterized in that it is one of octylcyclohexyl ether, cetylpyridinium chloride (CPC), cetyltrimethylammonium bromide (CTAB) or cetyltrimethylammonium chloride (CTAC), or a complex thereof. gas diffusion layer for metal-air batteries. The gas diffusion layer for a metal-air battery according to claim 1, further comprising a metal layer disposed along the surface of the conductive carbon layer. The gas diffusion layer of claim 1, further comprising a conductive polymer layer disposed along the surface of the conductive carbon layer. The adhesive layer includes polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyaniline (PANI), poly(diallyldimethylammonium chloride) (PDDA), polyethylene oxide (PEO), polyethyleneimine (PEI), polyallylamine chlorate ( PAH), polyacrylic acid, Nafion (registered trademark) (tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer). 2. The gas diffusion layer for a metal-air battery according to 1 . applying an adhesive layer to the surfaces of the plurality of non-transmitting fiber structures;
depositing a conductive carbon layer comprising a carbon material on top of the adhesion layer ;
The step of attaching the adhesive layer and the step of attaching the conductive carbon layer are repeatedly performed, and the plurality of adhesive layers and the plurality of conductive carbon layers are alternately arranged. A method for producing a gas diffusion layer for a metal-air battery. The method of claim 12 , further comprising uniformly dispersing the carbon material using a dispersant. The adhesive layer includes polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyaniline (PANI), poly(diallyldimethylammonium chloride) (PDDA), polyethylene oxide (PEO), polyethyleneimine (PEI), polyallylamine chlorate ( PAH), polyacrylic acid, Nafion (registered trademark) (tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer), or a complex thereof 13. The method for producing a gas diffusion layer for a metal-air battery according to claim 12 . The dispersant includes polystyrene sulfonate (PSS), polystyrene sulfonic acid, polyvinylpyrrolidone (PVP), polyethylene glycol oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene nonylphenyl ether, poly(ethylene glycol)-block-poly(propylene). glycol)-block-poly(ethylene glycol) (Pluronic), poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol), polyethylene-block-poly(ethylene glycol), polyoxyethylene iso 14. The method according to claim 13 , characterized in that it is one of octylcyclohexyl ether, cetylpyridinium chloride (CPC), cetyltrimethylammonium bromide (CTAB) or cetyltrimethylammonium chloride (CTAC), or a complex thereof. and a method for producing a gas diffusion layer for a metal-air battery. a negative electrode comprising a metal;
a positive electrode comprising a positive electrode catalyst layer and a metal-air battery gas diffusion layer in contact therewith;
and an electrolyte provided between the negative electrode and the positive electrode,
The gas diffusion layer for a metal-air battery is
a porous layer comprising a plurality of non-transmitting fiber structures;
a conductive carbon layer comprising a carbon material, said carbon material disposed along a surface of said fiber structure;
an adhesion layer disposed between the fiber structure and the conductive carbon layer to adhere the conductive carbon layer to the surface of the fiber structure ;
The metal-air battery , wherein the adhesive layers and the conductive carbon layers are provided in a plurality of layers, and the adhesive layers of the plurality of layers and the conductive carbon layers of the plurality of layers are alternately arranged. . 17. The metal-air battery according to claim 16 , wherein said gas diffusion layer for metal-air batteries has a porosity of 70 vol % or more. 17. The metal-air battery according to claim 16 , wherein the gas diffusion layer for a metal-air battery has a weight per unit area of 2 mg/cm< ² > or less. 17. The metal-air battery according to claim 16 , wherein the electrical conductivity of said gas diffusion layer for metal-air battery is 200 S/m or more. 17. The metal-air battery of claim 16 , wherein said conductive carbon layer is a conformal layer that conforms to the contour of said fiber structure.

Images