KR20190143821A - Current collector, electrode and lithium secondary battery comprising the same - Google Patents

Abstract

The present invention relates to a current collector, a lithium electrode comprising the same and a lithium secondary battery. More specifically, by preparing a current collector having a three-dimensional structure, in which pores are formed, by using metal powder and a binder, porosity and pore size of the current collector can be easily adjusted and a current collector of a thin film can be manufactured.

Description

Current collector, electrode and lithium secondary battery comprising same {CURRENT COLLECTOR, ELECTRODE AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME}

The present invention relates to a current collector, an electrode including the same, and a lithium secondary battery.

Recently, interest in energy storage technology is increasing. As the field of application extends to the energy of mobile phones, camcorders, notebook PCs, and even electric vehicles, efforts for research and development of electrochemical devices are becoming more concrete. The electrochemical device is the area that is receiving the most attention in this respect, and the development of a secondary battery capable of charging and discharging has been the focus of attention, and in recent years in the development of such a battery in order to improve the capacity density and specific energy R & D on the design of electrodes and batteries is underway.

Among the secondary batteries currently applied, lithium secondary batteries developed in the early 1990s have a higher operating voltage and greater energy density than conventional batteries such as Ni-MII, Ni-Cd, and sulfuric acid-lead batteries that use an aqueous electrolyte solution. I am in the spotlight.

In general, a lithium secondary battery is embedded in a battery case in a structure in which an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode is stacked or wound, and the nonaqueous electrolyte is injected therein.

At this time, when using a lithium electrode as said negative electrode, the lithium electrode formed by attaching a lithium foil on the planar collector generally has been used. However, as the high capacity and long life of the lithium secondary battery are required, a current collector having a three-dimensional structure has been developed to improve the capacity of the lithium secondary battery and to suppress a decrease in capacity during repeated charge and discharge cycles. .

Japanese Patent Laid-Open No. 2014-032798 relates to a nonaqueous electrolyte secondary battery, and discloses a secondary battery using a porous aluminum current collector having a three-dimensional structure as a positive electrode current collector and a negative electrode current collector. By using a porous aluminum current collector as the current collector, it is described that the nonaqueous electrolyte secondary battery has high capacity and excellent charge / discharge cycle characteristics and safety is improved.

However, the current collector of the three-dimensional structure is manufactured by synthesis, reduction, electrospinning, etc. using the metal itself as a raw material of the current collector, so that the characteristics of the three-dimensional structure current collector such as thickness, pore size, and porosity It was not easy to adjust.

Therefore, it is necessary to develop a technology capable of further improving the performance of a lithium secondary battery by manufacturing a current collector having various shapes of three-dimensional structures.

Japanese Laid-Open Patent No. 2014-032798 (2014.02.20)

Accordingly, the present inventors have conducted various studies to solve the above problems, and as a result, by preparing a current collector having a three-dimensional structure in which pores are formed by using metal powder and a binder, the porosity and the pore size of the current collector are easy. It was confirmed that it can be adjusted, and to prepare a current collector of a thin thickness.

An object of the present invention is to provide a three-dimensional structure current collector and a method of manufacturing the same.

Another object of the present invention is to provide an electrode including a three-dimensional structure current collector.

Still another object of the present invention is to provide a lithium secondary battery including an electrode including a three-dimensional structure current collector.

In order to achieve the above object, the present invention provides a current collector, including a metal and a binder, having a three-dimensional structure.

The metal may be at least one electrically conductive metal selected from the group consisting of Al, Cu, Zn, Au, Ag, and alloys thereof.

The binder is polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-hexafluoro propylene (PVDF-HFP), polyvinylidene fluoride-trichloro Polyvinylidene fluoride-co-trichloroethylene, polybutyl acrylate, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate (polyvinylacetate), ethylene vinyl co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose Cellulose acetate propionate, cyanoethylpullu (cyanoethylpullulan), cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, styrenebutadiene rubber Styrene-butadiene rubber), acrylonitrile-styrene-butadiene copolymer (acrylonitrile-styrene-butadiene copolymer) and polyimide may be one or more selected from the group consisting of.

The current collector may include 50 to 95 wt% of the metal and 5 to 50 wt% of the binder.

The pore size of the current collector may be 50 nm to 10 μm.

The thickness of the current collector may be 200 nm to 10 μm.

This invention also provides the manufacturing method of an electrical power collector using metal powder and a binder.

Method for producing a current collector, (A1) dissolving a metal powder and a binder in an organic solvent to obtain a slurry; (A2) applying the slurry on a substrate to form a coating layer for forming a current collector; (A3) drying the coating layer for forming the current collector; And (A4) rolling the substrate and the coating layer for forming a current collector after the drying.

In addition, the method of manufacturing the current collector may include forming a binder layer by applying the binder on a release film (B1); (B2) depositing the metal powder on the binder layer to form a metal layer; And (B3) separating the release film.

50 to 95% by weight of the metal powder and 5 to 50% by weight of the binder may be dissolved in an organic solvent.

The particle diameter of the metal powder may be 50 nm to 45 μm.

The organic solvent is acetonitrile, acetone, acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrroli It may be at least one selected from the group consisting of pig (N-methyl-2-pyrrolidone, NMP) and cyclohexane.

The present invention also provides an electrode comprising the current collector.

The present invention also provides a lithium secondary battery including the current collector.

According to the present invention, it is possible to easily adjust the characteristics of the current collector itself, such as porosity, pore size and specific surface area in the manufacturing process of the three-dimensional structure current collector, to prevent lithium dendrite growth when applied to a lithium secondary battery, The performance of the battery can be improved.

In addition, according to the present invention, a current collector of a thin film can be manufactured, which can be advantageous for commercialization of a lithium secondary battery.

Hereinafter, the present invention will be described in more detail.

House

The present invention relates to a current collector comprising a metal and a binder, and having a three dimension structure. The three-dimensional structure may be formed by pores.

In the present invention, the metal may be an electrically conductive metal, for example, the electrically conductive metal may be one or more selected from the group consisting of Al, Cu, Au, Ag, and alloys thereof. Depending on the redox potential of the metal can be used as a positive electrode current collector or a negative electrode current collector. Preferably, the positive electrode current collector may include Al metal, and the negative electrode current collector may use a Cu current collector.

Specifically, the current collector may be a three-dimensional structure including a mixture of the metal and the binder.

In the present invention, the content of the metal contained in the current collector may be 50 to 95% by weight, preferably 55 to 90% by weight, more preferably 60 to 85% by weight. If it is less than the above range, the electrical conductivity of the current collector may be lowered. If it is more than the above range, the content of the binder may be relatively lowered, thereby lowering the mechanical properties of the current collector.

In the present invention, the content of the binder contained in the current collector may be 5 to 50% by weight, preferably 10 to 45% by weight, more preferably 15 to 40% by weight. If the range is less than the above range, the mechanical properties of the current collector may be lowered. If the range is more than the range, the metal content may be relatively lowered, thereby decreasing the electrical conductivity of the current collector.

In the present invention, the binder is polyvinylidene fluoride (polyvinylidene fluoride (PVDF)), polyvinylidene fluoride-hexafluorofluoropropylene (polyvinylidene fluoride-co-hexafluoro propylene, PVDF-HFP), polyvinylidene Polyvinylidene fluoride-co-trichloroethylene, polybutyl acrylate, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone ), Polyvinylacetate, ethylene vinyl co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butylate acetate butyrate), cellulose acetate propionate , Cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose ), Styrene-butadiene rubber, acrylonitrile-styrene-butadiene copolymer (acrylonitrile-styrene-butadiene copolymer) and polyimide may include one or more selected from the group consisting of. In consideration of the adhesion and the mixing with the metal powder, the binder may preferably be polyvinylidene fluoride (PVDF).

In the present invention, the pore size of the current collector may be 50 nm to 10 μm, preferably 100 nm to 5 μm, and more preferably 150 nm to 3 μm. In this case, the pore size means the length of the longest axis measured in the pore. If the pore size is less than 50 nm, the effect of inhibiting lithium dendrite growth may be insignificant. If the pore size is greater than 10 μ, mechanical properties of the current collector may be reduced.

In the present invention, the thickness of the current collector may be 200 nm to 10 μm, preferably 250 nm to 5 μm, and more preferably 300 nm to 3 μm. When the thickness of the current collector is less than 200 nm, the durability of the current collector may be reduced, and when the thickness of the current collector is greater than 10 μm, the battery may be thickened.

Since the current collector of the three-dimensional structure including pores and the metal and the binder according to the present invention exhibits stable characteristics within a 0 to 3 V or 2 to 4.5 V potential with respect to the redox potential of the lithium metal, the lithium secondary It is suitable as a positive electrode or negative electrode current collector of a battery.

In addition, the current collector according to the present invention is suitable as a current collector for a lithium secondary battery using an electrolyte because it has electrolyte wetting characteristics and porosity and pore size suitable for movement of lithium ions.

Manufacturing method of current collector

The present invention also relates to a method for producing a current collector using a metal powder and a binder.

The method of manufacturing the current collector may include a method (1) of manufacturing a current collector and a method (2) of manufacturing a current collector, as described below.

Manufacturing method of current collector (1)

The present invention also comprises the steps of (A1) dissolving a metal powder and a binder in an organic solvent to obtain a slurry; (A2) applying the slurry on a substrate to form a coating layer for forming a current collector; (A3) drying the coating layer for forming the current collector; And (A4) rolling the substrate and the coating layer for forming a current collector after the drying.

Hereinafter, the manufacturing method of the current collector in each step will be described in more detail.

(A1) step

In step (A1), the metal powder and the binder may be dissolved in an organic solvent to obtain a slurry.

The weight of the metal powder dissolved in the organic solvent may be 50 to 95% by weight, preferably 55 to 90% by weight, and more preferably 60 to 85% by weight, based on the total weight of the metal powder and the binder. If the metal powder is less than 50% by weight, the electrical conductivity of the current collector may be lowered. If the metal powder is more than 95% by weight, the binder content may be relatively lowered, thereby lowering the mechanical properties of the current collector.

In addition, the weight of the binder dissolved in the organic solvent may be 5 to 50% by weight, preferably 10 to 45% by weight, and more preferably 15 to 40% by weight, based on the total weight of the metal powder and the binder. If the weight of the binder is less than 5% by weight, the mechanical properties of the current collector may be lowered. If the weight of the binder is greater than 50% by weight, the metal content may be relatively lowered, thereby lowering the electrical conductivity of the current collector.

In addition, the weight ratio of the organic solvent to the solid content of the metal powder and the binder may be 5:95 to 90:10, preferably 20:80 to 80:20, and more preferably 30:70 to 70:30. If the weight ratio of the solvent to the solid content is less than the above range, the physical properties of the current collector to be produced are not good, and if it exceeds the above range, the coating process may not be performed smoothly.

In the present invention, the organic solvent may be a solvent capable of sufficiently dissolving the metal powder and the binder, the volatilization upon drying to form pores in the current collector.

For example, the organic solvent may be acetonitrile, acetone, acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2- It may be at least one selected from the group consisting of pyrrolidone (N-methyl-2-pyrrolidone, NMP) and cyclohexane (cyclohexane). Preferably, the organic solvent may be acetone.

In the present invention, the metal powder may use a powder of metals as described above.

The particle diameter of the metal powder may be 200 nm to 45 μm, preferably 250 nm to 40 μm, and most preferably 300 nm to 35 μm. If the particle diameter of the metal powder is less than 200 nm, the mechanical properties of the current collector may be lowered. If the particle size of the metal powder is greater than 45 μm, the mixing properties with the binder may not be good, and thus the progress of the current collector manufacturing process may be difficult. The smaller the particle diameter of the metal powder is, the greater the risk of ignition in the air, so the processability is lower. However, as the particle diameter of the metal powder is smaller, the size of the pores can be adjusted, so that the particle size of the metal powder has fairness, and it is preferable to appropriately adjust it within a range in which the pores are not excessively large.

In the present invention, the type of the binder is as described above.

(A2) step

In step (A2), the slurry may be applied onto a substrate to form a coating layer for forming a current collector.

The substrate is not particularly limited as long as it is a substrate capable of forming a coating process. The substrate is polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate (PC), polypropylene (PP), polyvinyl chloride (PVC), polyethylene (PE), polymethyl It may be selected from the group consisting of methacrylate (PMMA), polyamide and polyimide. Preferably the substrate may be polyethylene terephthalate (PET).

As a method for forming the current collector-forming coating layer, dip coating, gravure coating, slit die coating, spin coating, comma coating, The coating method may be selected from the group consisting of bar coating, reverse roll coating, screen coating, and cap coating. Preferably, a bar coating or casting method which is easy to control the thickness of the coating layer may be used.

(A3) step

In step (A3), the coating layer for forming the current collector may be dried. When drying, the organic solvent included in the slurry is removed by volatilization, thereby preparing a current collector having a three-dimensional structure in which pores are formed.

The drying temperature may be 25 ℃ to 150 ℃, preferably 40 ℃ to 130 ℃, more preferably 80 ℃ to 120 ℃. When the drying temperature is less than the above range, the drying is not sufficiently performed to obtain a finished product current collector, and when the drying temperature exceeds the above range, pores may be excessively formed, thereby reducing durability of the current collector.

The drying method may be a method selected from the group consisting of vacuum drying, hot air drying, NIR (Near Infra-Red) drying and superheated steam drying. Preferably, in consideration of the sufficient degree of volatilization and pore formation of the organic solvent, it can be dried using vacuum drying.

(A4) step

In step (A4), the porosity of the coating layer may be adjusted by rolling the substrate and the coating layer formed on the substrate.

Specifically, the pressure applied during the rolling is dependent on the thickness and porosity of the current collector, the porosity of the current collector is 20% to 90%, preferably 30% to 80%, more preferably 40% to 70 Can be%. If the range is less than the above range, the lithium dendrite growth inhibiting effect of the lithium secondary battery to which the current collector is applied is insignificant. If the range exceeds the range, mechanical properties of the current collector may be reduced.

Manufacturing method of current collector (2)

The present invention also (B1) by applying the binder on the release film to form a binder layer; (B2) depositing the metal powder on the binder layer to form a metal layer; And (B3) separating the release film.

(B1) step

In the step (B1), the release film may be those known in the art, for example, polyethylene terephthalate (PET) film may be used.

The method of applying the binder may be a coating method commonly used in the art, for example, dip coating, gravure coating, slit die coating as described above. Selected from the group consisting of spin coating, comma coating, bar coating, reverse roll coating, screen coating and cap coating Coating method.

(B2) step

In step (B2), the metal powder may be deposited on the binder layer to form a metal layer.

As the deposition method, physical vapor deposition (PVD) may be thermal evaporation, e-beam evaporation, or sputtering.

By depositing using the metal powder, a metal layer having a three-dimensional structure in which pores are formed may be formed.

(B3) step

In the step (B3), by separating the release film, it is possible to produce a three-dimensional current collector comprising a mixture of the metal and the binder.

The binder layer formed in the step (B1) is formed in a thin film form, and because the physical energy is large when laminating the metal powder of the (B2) step, the binder layer and the metal layer separately in the current collector to be manufactured Without distinguishing, a current collector in which a binder and a metal powder are mixed is formed.

electrode

The invention also relates to an electrode comprising the current collector as described above.

The current collector may be used as a positive electrode current collector or a negative electrode current collector according to the redox potential of the metal included with the binder. For example, if the current collector includes an Al metal, it may be used as a positive electrode current collector, and if the current collector includes Cu metal, it may be used as a negative electrode current collector. The Al is unstable by forming an alloy with Li at a potential difference in the range of 0 V with respect to Li, and the Cu is oxidized at 3.4 V or more compared with Li, so that Al is difficult to use as a negative electrode current collector and the Cu is a positive electrode current collector. Can be difficult to use

When the current collector according to the present invention is used for a negative electrode of a lithium secondary battery, the negative electrode may be a lithium electrode including lithium metal formed on at least one surface of the negative electrode current collector.

In addition, when the current collector according to the present invention is used for the positive electrode of the lithium secondary battery, the positive electrode may include a positive electrode active material layer formed on at least one surface of the positive electrode current collector. In this case, the positive electrode may include a positive electrode current collector and a positive electrode active material layer coated on one or both surfaces thereof. The cathode active material included in the cathode active material layer is LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiCoPO ₄ , LiFePO ₄ , LiNiMnCoO ₂ and LiNi _{1- xy- z} Co _x M1 _y M2 _z O ₂ (M1 and M2 is Independently from each other Al, Ni, Co, Fe, Mn, V, Cr, Ti, W, Ta, Mg and Mo is any one selected from the group, x, y and z are the atomic fraction of the elements of the oxide composition independently of each other And 0 ≦ x <0.5, 0 ≦ y <0.5, 0 ≦ z <0.5, and x + y + z ≦ 1) or two or more of these slurries.

Lithium secondary battery

The present invention also includes an electrode assembly including a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode; A battery case accommodating the electrode assembly; And a nonaqueous electrolyte solution embedded in the battery case and impregnating the electrode assembly, wherein the positive electrode or the negative electrode may include a current collector having a three-dimensional structure as described above.

The positive electrode and the negative electrode are as described above.

The separator may be made of a porous substrate, and the porous substrate may be used as long as it is a porous substrate commonly used in an electrochemical device. For example, a polyolefin-based porous membrane or a nonwoven fabric may be used. It is not specifically limited.

Examples of the polyolefin-based porous membrane, polyolefin-based polymers, such as polyethylene, polypropylene, polybutylene, polypentene, such as high density polyethylene, linear low density polyethylene, low density polyethylene, ultra high molecular weight polyethylene, respectively, or a mixture thereof One membrane may be mentioned.

The nonwoven fabric may include, for example, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, or polycarbonate. ), Polyimide, polyetheretherketone, polyethersulfone, polyphenyleneoxide, polyphenylenesulfide and polyethylenenaphthalene, alone or in combination The nonwoven fabric formed from the polymer which mixed these is mentioned. The structure of the nonwoven can be a spunbond nonwoven or melt blown nonwoven composed of long fibers.

The thickness of the porous substrate is not particularly limited, but may be 1 μm to 100 μm, preferably 3 μm to 50 μm, and more preferably 5 μm to 30 μm. The pore size and pore present in the porous substrate are also not particularly limited, but may be 0.001 μm to 50 μm and 10% to 95%, respectively.

In addition, the electrolyte salt contained in the nonaqueous electrolyte solution which can be used in the present invention is a lithium salt. The lithium salt may be used without limitation as those conventionally used in the lithium secondary battery electrolyte. For example, the lithium salt is LiFSI, LiPF ₆ , LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiPF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, may be one or more selected from the group consisting of lithium chloroborane and lithium 4-phenyl borate.

As the organic solvent included in the aforementioned non-aqueous electrolyte, those conventionally used in the lithium secondary battery electrolyte may be used without limitation, and for example, ethers, esters, amides, linear carbonates, and cyclic carbonates may be used alone or in combination of two or more. It can be mixed and used. Among them, a carbonate compound which is typically a cyclic carbonate, a linear carbonate, or a slurry thereof may be included.

Specific examples of the cyclic carbonate compound include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, vinylethylene carbonate, and any one selected from the group consisting of halides thereof, or two or more of these slurries. These halides include, for example, fluoroethylene carbonate (FEC), but are not limited thereto.

In addition, specific examples of the linear carbonate compound may be any one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate and ethylpropyl carbonate. Two or more of these slurries and the like may be representatively used, but are not limited thereto. In particular, ethylene carbonate and propylene carbonate, which are cyclic carbonates among the carbonate-based organic solvents, have high dielectric constants and can dissociate lithium salts in the electrolyte more efficiently. By using a low viscosity, low dielectric constant linear carbonate mixed in an appropriate ratio it can be made an electrolyte having a higher electrical conductivity.

In addition, as the ether in the organic solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methylethyl ether, methylpropyl ether, and ethylpropyl ether or two or more of these slurries may be used. It is not limited to this.

In addition, the ester in the organic solvent is methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, γ-valerolactone, γ-caprolactone, Any one selected from the group consisting of α-valerolactone and ε-caprolactone or two or more of these slurries may be used, but is not limited thereto.

The injection of the nonaqueous electrolyte may be performed at an appropriate step in the manufacturing process of the electrochemical device, depending on the manufacturing process and the required physical properties of the final product. That is, it may be applied before the electrochemical device assembly or the final step of the electrochemical device assembly.

The lithium secondary battery according to the present invention may be a lamination (stack) and folding process of the separator and the electrode in addition to the winding (winding) which is a general process.

In addition, the shape of the battery case is not particularly limited, and may be in various shapes such as cylindrical, stacked, square, pouch or coin type.

The present invention also provides a battery module including the lithium secondary battery as a unit cell.

The battery module may be used as a power source for medium and large devices requiring high temperature stability, long cycle characteristics, and high capacity characteristics.

Examples of the medium-to-large device include a power tool that is driven by an electric motor; Electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like; Electric motorcycles including electric bicycles (E-bikes) and electric scooters (E-scooters); Electric golf carts; Power storage systems and the like, but is not limited thereto.

Hereinafter, preferred examples are provided to help the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and various changes and modifications within the scope and spirit of the present invention are apparent to those skilled in the art. It goes without saying that changes and modifications belong to the appended claims.

In the following Examples, Comparative Examples, and Experimental Examples, a current collector having a three-dimensional structure with pores is called a 3D structural current collector, and a current collector having a structure without pores is called a 2D structural current collector.

Example 1 Preparation of 3D Structure Current Collector including Cu and PVDF and Half Cell Using the Same

(1) 3D structure collector

Cu powder was used as the metal, and the Cu powder particles were non-uniform particles (dendritic, CAS Number 7440-50-8) having a particle diameter of 1 to 45 μm.

Cu powder and PVDF-HFP binder were dissolved in an acetone solvent to obtain a slurry in which the weight of the Cu powder and the binder was 20% by weight based on the weight of the solvent (wherein the weight ratio of Cu and PVDF was 80:20).

The slurry was coated on a substrate by a doctor blade coating method to form a coating layer for forming a current collector.

Then, it dried and rolled and produced the 3D structural collector in which the pore was formed.

(2) electrode manufacturing

The negative electrode was manufactured by rolling a lithium metal layer having a thickness of 20 μm on one surface of the 3D structure current collector.

As the positive electrode, a 30 μm lithium metal layer without a current collector having the above-mentioned 3D structure was used for the half cell.

(3) Coin-type half battery manufacturing

After the polyolefin separator was interposed between the anode and the cathode prepared as described above, 1M LiPF ₆ and VC were dissolved in an electrolyte solution containing 2% by weight of 1M LiPF ₆ and VC in a volume ratio of 1: 2: 1. Coin type half cell was prepared (EC: ethylene carbonate, DEC: diethyl carbonate, DMC: dimethyl carbonate, VC: vinyl chloride).

Example 2

A 3D structure current collector and a battery were manufactured in the same manner as in Example 1, except that the weight ratio of Cu powder and PVDF-HFP binder was 95: 5.

Example 3

After coating the PVDF copolymer binder to 200 nm thickness on a silicon release film (SKC Haas, Inc.), Cu powder was vacuum deposited to form a Cu metal layer having a thickness of 50 nm, and then the release film was separated to separate Cu and PVDF. A battery was prepared in the same manner as in Example 1, except that the mixture of -HFP prepared a current collector having a 3D structure. The Cu powder particles are non-uniform particles having a particle diameter between 50 nm and 2 μm.

Example 4

A 3D structure current collector and a battery were manufactured in the same manner as in Example 3, except that Au powder was used instead of Cu powder.

Example 5

A 3D structure current collector and a battery were manufactured in the same manner as in Example 3, except that Ag powder was used instead of Cu powder.

Comparative Example 1: Preparation of 2D Structure Cu Current Collector and Half Battery Using the Same

A half cell was produced in the same manner as in Example 1 using a Cu foil as a 2D structure Cu current collector.

Comparative Example 2: 3D structure Cu current collector and half cell manufacturing using same

A 3D structure current collector and a battery were manufactured in the same manner as in Example 1, except that the weight ratio of Cu powder and PVDF-HFP binder was 99: 1.

Comparative Example 3: 3D structure Cu current collector and half cell manufacturing using the same

A 3D structure current collector and a battery were manufactured in the same manner as in Example 1, except that the weight ratio of Cu powder and PVDF-HFP was 45:55.

Comparative Example 4: 3D structure Cu current collector and half cell manufacturing using same

A 3D structure current collector and a battery were manufactured in the same manner as in Example 3, except that Ni powder was used instead of Cu powder.

Comparative Example 5: 3D foam-shaped Cu current collector and a half cell manufacturing using the same

A battery was prepared in the same manner as in Example 1 using a 3D foam-shaped Cu current collector (100 μm thick).

Experimental Example 1: Measurement of Life Characteristics

The half cells prepared in Examples 1 to 5 and Comparative Examples 1 to 5 were maintained at room temperature (25 ° C.) for 1 day, and then charged to a capacity of 3 mAh / cm 2 at 0.2 C constant current. Thereafter, discharge was performed until the voltage reaches 2.0 V at a constant current of 0.2 C, thereby performing initial charge and discharge. The subsequent charge / discharge was similarly charged and discharged at a 0.2C constant current. After repeating this as one cycle, the cycle at the first cycle efficiency and the capacity retention rate of 50% is shown in Table 1 below.

House
Formation Weight ratio
(Metal: binder) Particle size of metal powder Half cell
First cycle
efficiency (%) Half cell
50% or more capacity retention
Cycle Example 1 ○ 80:20 1 ~ 45 ㎛ 90.7 12 Example 2 ○ 95: 5 1 ~ 45 ㎛ 90.2 9 Example 3 ○ 50:50 50 nm to 2 μm 92.1 13 Example 4 ○ 50:50 50 nm to 2 μm 95.1 15 Example 5 ○ 50:50 50 nm to 2 μm 96.3 16 Comparative Example 1 - 100: 0 - 89.1 9 Comparative Example 2 X 99: 1 1 ~ 45 ㎛ - - Comparative Example 3 ○ 45:55 50 nm to 2 μm 88.3 7 Comparative Example 4 ○ 50:50 50 nm to 2 μm 86.6 4 Comparative Example 5 - 100: 0 - 90.5 11

Referring to Table 1, in the case of Examples 1 to 5 including the metal powder and the binder in an appropriate weight ratio, it can be seen that the life characteristics are excellent.

In addition, in Comparative Example 2, since the content of the PVDF-HFP binder is excessively less than that of the Cu powder, the Cu powder cannot be sufficiently connected. The current collector was not formed and crumbled.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto. Various modifications and variations are possible without departing from the scope of the appended claims.

Claims (14)

A current collector, comprising a metal and a binder, having a three-dimensional structure. The method of claim 1,
The metal is a current collector, which is an electrically conductive metal selected from the group consisting of Al, Cu, Zn, Au, Ag and alloys thereof. The method of claim 1,
The binder is polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-hexafluoro propylene (PVDF-HFP), polyvinylidene fluoride-trichloro Polyvinylidene fluoride-co-trichloroethylene, polybutyl acrylate, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate (polyvinylacetate), ethylene vinyl co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose Cellulose acetate propionate, cyanoethylpullu (cyanoethylpullulan), cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, styrenebutadiene rubber At least one member selected from the group consisting of styrene-butadiene rubber, acrylonitrile-styrene-butadiene copolymer and polyimide. The method of claim 1,
The current collector comprises 50 to 95% by weight of the metal and 5 to 50% by weight binder. The method of claim 1,
The pore size of the current collector is included in the current collector, 50 nm to 10 μm The method of claim 1,
The current collector has a thickness of 200 nm to 10 μm. The manufacturing method of an electrical power collector using metal powder and a binder. The method of claim 7, wherein
The manufacturing method of the current collector
(A1) dissolving a metal powder and a binder in an organic solvent to obtain a slurry;
(A2) applying the slurry on a substrate to form a coating layer for forming a current collector;
(A3) drying the coating layer for forming the current collector; And
(A4) rolling the substrate and the coating layer for forming a current collector after the drying;
Method for producing a current collector comprising a. The method of claim 7, wherein
The manufacturing method of the current collector
(B1) forming a binder layer by applying the binder on a release film;
(B2) depositing the metal powder on the binder layer to form a metal layer; And
(B3) separating the release film;
Method for producing a current collector comprising a. The method of claim 7, wherein
50 to 95% by weight of the metal powder and 5 to 50% by weight of the binder, the method of producing a current collector. The method of claim 7, wherein
Particle diameter of the metal powder is 50 nm to 45 ㎛ method of manufacturing a current collector. The method of claim 8,
The organic solvent is acetonitrile, acetone, acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrroli A method for producing a current collector, which is at least one member selected from the group consisting of ton (N-methyl-2-pyrrolidone, NMP) and cyclohexane. An electrode comprising the current collector of any one of claims 1 to 6. A lithium secondary battery comprising the current collector of any one of claims 1 to 6.