Current collector comprising a polymer film and method for manufacturing the same

Abstract

The present technology relates to a current collector and a method for manufacturing the same. The current collector of the present technology is a current collector including a composite polymer film layer, and the composite polymer film layer includes: a polymer matrix; and a fibrous or platy metal material dispersed in the polymer matrix, and the metal material is oriented in one direction.

Description

Technical Field

[0001] This application claims priority based on Korean Patent Application No. 10-2021-0059193, filed on May 7, 2021, the entire contents of which are incorporated herein by reference.

[0002] This invention relates to current collectors and methods for manufacturing the same, and more specifically, to current collectors comprising polymer membranes and methods for manufacturing the same. Background Technology

[0003] In recent years, rechargeable and discharging secondary batteries have been widely used as energy sources for wireless mobile devices. Furthermore, secondary batteries have attracted attention as an energy source for electric vehicles, hybrid electric vehicles, and other vehicles designed as a solution to air pollution from existing gasoline and diesel vehicles that use fossil fuels. Therefore, due to the advantages of secondary batteries, their applications are currently very diverse, and it is expected that they will be used in many fields and products in the future.

[0004] These secondary batteries can be classified according to the composition of their electrodes and electrolytes, such as lithium-ion batteries, lithium-ion polymer batteries, and lithium polymer batteries. Among them, the use of lithium-ion polymer batteries, which are less likely to leak electrolytes and are easy to manufacture, is increasing. Generally, secondary batteries are classified according to the shape of their casings, such as cylindrical batteries and prismatic batteries (where the electrode assembly is housed in a cylindrical or square metal can) and pouch batteries (where the electrode assembly is housed in a pouch-shaped casing of aluminum laminates). The electrode assembly built into the battery casing consists of a positive electrode, a negative electrode, and a separator placed between the positive and negative electrodes, and is a power generation element capable of charging and discharging. Electrode assemblies are classified into wound-core type with a wound separator, where the separator is placed between the positive and negative electrodes, which are elongated sheets coated with active material, and stacked type, where multiple positive and negative electrodes of predetermined sizes are stacked sequentially, with the separator placed between them.

[0005] These electrodes can be manufactured by coating a current collector with an electrode slurry containing an electrode active material and then drying the electrode slurry to form an electrode mixture layer. In this case, the current collector can generally be made of a metal with excellent conductivity (such as copper or aluminum). In order to reduce the weight of the current collector, current collectors obtained by compositing polymer films with metals are being developed.

[0006] However, for current collectors obtained by combining such polymers with metals, the elastic modulus of the polymer film is typically 0.1 to 5 GPa, which is much lower than that of copper (117 GPa) or aluminum (69 GPa). Therefore, in order to impart physical properties similar to those of metal current collectors, the thickness of the polymer-metal composite current collector should be set to more than 10 times that of a typical current collector. This leads to an increase in the volume and mass of the electrode. Summary of the Invention

[0007] [Technical Issues]

[0008] It is believed that the present invention solves at least some of the aforementioned problems. For example, one aspect of the present invention provides a polymer-metal composite current collector with improved mechanical properties and a method for manufacturing the same.

[0009] [Technical Solution]

[0010] The current collector of the present invention is a current collector comprising a composite polymer film layer. The composite polymer film layer comprises: a polymer matrix; and a fibrous or plate-like metal material dispersed in the polymer matrix, wherein the metal material is oriented in one direction.

[0011] In one specific example, the metallic material may be at least one selected from the group consisting of aluminum, copper, indium, titanium, tin, nickel, iron, tungsten, chromium, cobalt, gold, and silver, and the polymer film may be made of at least one selected from polyolefin resin, polyamide resin, polyester resin, and poly(meth)acrylate resin.

[0012] In a specific example, the cross-sectional diameter of the fibrous metal material can be from 10 to 500 nm, and the length of the fibrous metal material can be from 0.5 to 200 μm.

[0013] In a specific example, the thickness of the plate-shaped metal material can be from 10 to 500 nm, and the width and length of the plate-shaped metal material can be from 0.5 to 200 μm, respectively.

[0014] In one example, the metallic material may contain more than two different kinds of metals.

[0015] In one specific example, the angle between the metal material and the length axis of the polymer film is equal to or less than 20°, and the angle between the metal material and the thickness axis of the polymer film is 70 to 90°.

[0016] In one specific example, the thickness of the polymer film can be from 10 to 200 μm.

[0017] In another example, the current collector may further include a metal layer formed on at least one surface of the polymer film and having a thickness of less than 1 μm.

[0018] Furthermore, the present invention provides a method for manufacturing the above-mentioned current collector.

[0019] The method for manufacturing a current collector according to the present invention includes: depositing metal on at least one surface of a base membrane made of a polymer material to form a deposited layer; pulverizing and mixing the base membrane on which the deposited layer is formed, and then extruding the base membrane for the first time to manufacture a polymer-metal composite material; and extruding the polymer-metal composite material to form a polymer film layer in which fibrous or plate-like metal material is oriented in one direction in a polymer matrix.

[0020] In one specific example, the metal may be at least one selected from the group consisting of aluminum, copper, indium, titanium, tin, nickel, iron, tungsten, chromium, cobalt, gold, and silver, and the base membrane may be made of at least one selected from polyolefin resin, polyamide resin, polyester resin, and poly(meth)acrylate resin.

[0021] In a specific example, the thickness of the deposited layer can be 50 to 400 nm, and the thickness of the base film can be 20 to 400 μm.

[0022] At this point, the volume ratio of the deposited layer to the base film can be from 0.5:99.5 to 10:90.

[0023] In one example, the deposited layer can have a structure in which two or more different metal layers are stacked together.

[0024] In a specific example, a base film with a deposited layer formed on it can be extruded using a twin-screw extruder.

[0025] Furthermore, the extrusion of polymer-metal composites can be carried out using a single-screw extruder.

[0026] In another example, the method for manufacturing the current collector of the present invention may further include forming a metal layer on at least one surface of the polymer film layer.

[0027] [Beneficial Effects]

[0028] According to the present invention, by dispersing fibrous or plate-shaped metal materials in a polymer film layer and oriented in one direction, the mechanical properties of a current collector comprising a polymer film layer can be improved. Attached Figure Description

[0029] Figure 1 This is a schematic diagram showing a cross-section of the current collector along its length according to one embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram showing a cross-section of the current collector in the width direction according to one embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram showing a cross-section of the current collector along its length, according to another embodiment of the present invention.

[0032] Figure 4 This is a flowchart illustrating the sequence of the method for manufacturing the current collector according to the present invention.

[0033] Figure 5 This is a schematic diagram illustrating the sequence and variations of the manufacturing method of the current collector of the present invention.

[0034] Figures 6 to 8 This is a schematic diagram illustrating each process in the manufacturing method of the current collector of the present invention.

[0035] Figures 9 to 11 These are SEM images showing cross-sections of the polymer films of the embodiments and comparative examples, and images showing elemental distributions. Detailed Implementation

[0036] The invention will be described in detail below with reference to the accompanying drawings. The terms and words used in this specification and claims should not be construed as limited to common or dictionary terms, and the inventors may appropriately define the concepts of the terms in order to best describe their invention. Terms and words should be interpreted as having meanings and concepts consistent with the technical spirit of the invention.

[0037] In this application, it should be understood that terms such as "comprising" or "having" are intended to indicate the presence of the features, figures, steps, operations, components, parts, or combinations thereof described in the specification, and they do not preclude the possibility of the presence or addition of one or more other features or figures, steps, operations, components, parts, or combinations thereof. Furthermore, when a portion such as a layer, membrane, region, or plate is referred to as being "on" another portion, this includes not only the case where that portion is "directly on" the other portion, but also the case where another portion is inserted therein. On the other hand, when a portion such as a layer, membrane, region, or plate is referred to as being "below" another portion, this includes not only the case where that portion is "directly below" the other portion, but also the case where another portion is inserted therein. Additionally, the arrangement "on" in this application can include arrangements at the bottom and top.

[0038] Furthermore, in this invention, the length direction of the polymer film or current collector refers to the direction in which the polymer is extruded during the formation of the polymer film layer, or the direction in which the film moves during the manufacture and processing of the current collector (MD direction, x-axis direction). The width direction refers to the direction perpendicular to the length direction on the surface formed by the film layer (y-axis direction).

[0039] The invention will now be described in detail with reference to the accompanying drawings.

[0040] The current collector of the present invention is a current collector comprising a composite polymer film layer. The composite polymer film layer comprises: a polymer matrix; and a fibrous or plate-like metal material dispersed in the polymer matrix, wherein the metal material is oriented in one direction.

[0041] As mentioned above, for current collectors obtained by combining polymers and metals, the physical properties of the polymer film are generally much lower than those of the metal current collector. Therefore, in order to impart physical properties similar to those of metal current collectors, the thickness of the polymer-metal composite current collector should be set to more than 10 times the thickness of a typical current collector. This leads to an increase in the volume and mass of the electrode.

[0042] According to the present invention, by dispersing fibrous or plate-like metal materials in a polymer film layer, the mechanical properties of the current collector comprising the polymer film layer can be improved.

[0043] Figure 1 This is a schematic diagram showing a cross-section of the current collector along its length according to one embodiment of the present invention. Figure 2 This is a schematic diagram showing a cross-section of the current collector in the width direction according to one embodiment of the present invention.

[0044] refer to Figure 1 and 2 The current collector 1 of the present invention includes a polymer film layer 10. The polymer film layer 10 is the body of the current collector, making the current collector lightweight and providing flexibility compared to the use of metal.

[0045] like Figure 1 and 2 As shown, the polymer film 10 includes: a polymer matrix 11; and a metal material 12 dispersed in the polymer matrix 11.

[0046] As the polymer material used for the polymer matrix 11, a matrix that serves as a dispersion medium for the metal material described later, a material that provides flexibility to the current collector, and a material that has sufficient rigidity to be used as a current collector can be used. For example, the polymer membrane can be made of at least one selected from polyolefin resins, polyamide resins, polyester resins, and poly(meth)acrylate resins.

[0047] At this point, the polyolefin resin can be high-density, medium-density, low-density or linear low-density polyethylene, crystalline polypropylene, non-crystalline polypropylene or polybutene.

[0048] The polyamide resin can be nylon 6, nylon 6,6, nylon 610 or nylon 12.

[0049] The polyester resin can be polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or polyethylene naphthalate.

[0050] The poly(meth)acrylate alkyl resin can be polymethyl methacrylate, polymethyl acrylate, polyethyl acrylate or polybutyl acrylate.

[0051] The metallic material 12 has the smallest nanoscale size and is uniformly dispersed in the polymer matrix 11.

[0052] More specifically, the metal material 12 can be fibrous or plate-like. Here, fibrous means that the metal material 12 in the polymer matrix 11 has a fine fibrous shape, such as... Figure 2 As shown in (a). On the other hand, the plate-like shape of the metal material 12 means that the metal material 12 has a flat shape like a strip or sheet, such as Figure 2 As shown in (b).

[0053] That is, the metal material 12 has a shape that is longer along one direction. The metal material 12 improves the mechanical properties of the polymer film 10 by being oriented along one direction within the polymer matrix 11. Specifically, the metal material 12 can be oriented along the length direction (x-axis direction) of the polymer film 10, such as... Figure 1 and 2 As shown.

[0054] The metallic material can be at least one selected from the group consisting of aluminum, copper, indium, titanium, tin, nickel, iron, tungsten, chromium, cobalt, gold, and silver, but its type is not limited, as long as it can be easily processed with the film and can improve the mechanical properties of the polymer film layer. More specifically, as a metallic material, metals with melting points higher than the temperature set when extruding the materials constituting the polymer matrix as described below can be used, such as aluminum, copper, titanium, nickel, tungsten, and iron. This is because if the melting point is lower than the temperature set when molten extruding the polymer material, the metal may not form a plate-like or fibrous shape, but rather a spherical shape. For example, the melting point of the metallic material can be equal to or greater than 200°C, specifically 600°C, and more specifically 800°C.

[0055] If the metal material 12 is fibrous, the cross-sectional diameter of the metal material 12 can be 10 to 500 nm, 100 to 400 nm, or 150 to 350 nm, and the length of the metal material 12 can be 0.5 to 200 μm, 0.5 to 150 μm, or 0.5 to 100 μm.

[0056] Furthermore, if the metal material 12 is plate-shaped, the thickness of the metal material 12 can be 10 to 500 nm, 100 to 400 nm, or 150 to 350 nm, and the width and length of the metal material 12 can be 0.5 to 200 μm, 0.5 to 150 μm, or 0.5 to 100 μm.

[0057] When the size (diameter, thickness, or length) of the metallic material is too small, the effect of increasing physical properties is not significant. However, when the size of the metallic material is too large, as described below, the thickness of the deposited layer formed on the base film is too large. In this case, cracks may occur in the deposited layer, and costs may increase.

[0058] Similarly, by dispersing nanoscale fibrous or plate-like metal materials 12 in the polymer matrix 11, the metal materials 12 can be easily bonded to the polymer matrix 11 and can prevent the metal materials 12 from being discharged to the outside of the polymer matrix 11.

[0059] Furthermore, as described above, the mechanical properties of the polymer film 10 in the longitudinal direction can be improved by aligning the metal material 12 along the longitudinal direction (x-axis) of the polymer film 10. Specifically, the angle between the metal material 12 and the longitudinal axis (x-axis) of the polymer film 10 can be less than 20°, less than 15°, or less than 10°, and the angle between the metal material 12 and the thickness axis (z-axis) can be between 70° and 90°, or between 80° and 90°. Moreover, more than 80%, more than 90%, or more than 95% of the entire metal material can have the aforementioned orientation angles. When the degree of orientation of the metal material 12 is within the above ranges, the mechanical properties of the polymer film 10 can be effectively improved.

[0060] In one example, the metal material 12 may contain two or more different types of metals. This includes cases where different metal materials are made of different metals, as well as cases where one metal material contains two or more types of metals. Therefore, the strength, flexibility, and processability of the polymer film can be set to the desired level. In this case, the types and proportions (e.g., volume ratios) of the metal materials can be selected considering the desired strength, flexibility, and processability of the polymer film. For example, to enhance the strength of the polymer film, a relatively strong metal material can be used, while to enhance flexibility and processability, a relatively ductile metal material or a metal material with a relatively low melting point can be used.

[0061] Furthermore, the thickness of the polymer film layer can be from 10 to 200 μm, specifically from 50 to 150 μm. That is, the thickness of the current collector 1 of the present invention is similar to that of a general metal current collector, and it can exhibit mechanical properties similar to those of a metal current collector. When the thickness of the polymer film layer 10 is less than 10 μm, it is difficult to exhibit mechanical properties due to the excessively small thickness of the current collector, and when the thickness of the polymer film layer 10 exceeds 200 μm, the volume and weight of the electrode and battery cell increase due to the excessive increase in the thickness of the current collector.

[0062] Figure 3 This is a schematic diagram showing a cross-section of the current collector along its length, according to another embodiment of the present invention.

[0063] refer to Figure 3The current collector 2 of the present invention may further include a metal layer 20 formed on at least one surface of the polymer film layer 10. The metal layer 20 additionally supplements the mechanical rigidity of the polymer film layer 10 and increases the conductivity of the current collector 2.

[0064] For example, the metal layer 20 can be formed by deposition and has a thickness of less than 1 μm or less than 0.5 μm. Therefore, the increase in the volume and weight of the electrode can be minimized while supplementing the mechanical rigidity of the current collector 2 and improving the conductivity of the current collector 2. In addition, the thickness of the metal layer can be greater than 50 nm, greater than 100 nm, or greater than 200 nm.

[0065] Furthermore, the present invention provides an electrode comprising the current collector as described above.

[0066] The electrode includes an electrode mixture layer formed on at least one surface of the current collector. This electrode mixture layer is formed by coating the current collector with an electrode slurry comprising an electrode active material, a conductive material, and a binder. The electrode active material can be a positive electrode active material or a negative electrode active material.

[0067] In this invention, the positive electrode active material is a material capable of inducing an electrochemical reaction, and is a lithium transition metal oxide containing two or more transition metals. Examples include: layered compounds, such as lithium cobalt oxide (LiCoO2) and lithium nickel oxide (LiNiO2) substituted with one or more transition metals; lithium manganese oxide substituted with one or more transition metals; and compounds of the formula LiNi... 1-y M y Lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, Cr, Zn or Ga, and contains at least one of the above elements, 0.01≤y≤0.7); Li 1+z Ni b Mn c Co 1-(b+c+d) M d O (2-e) A e (where -0.5≤z≤0.5, 0.1≤b≤0.8, 0.1≤c≤0.8, 0≤d≤0.2, 0≤e≤0.2, b+c+d<1, M=Al, Mg, Cr, Ti, Si or Y, and A=F, P or Cl) represents lithium nickel cobalt manganese composite oxides, such as Li 1+z Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2, Li 1+ z Ni 0.4 Mn 0.4 Co 0.2O2, etc.; a lithium metal phosphate of olivine type represented by the formula Li 1+x M 1-y M' y PO 4-z X z (where M = transition metal, preferably Fe, Mn, Co or Ni, M' = Al, Mg or Ti, X = F, S or N, and -0.5 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.5, 0 ≤ z ≤ 0.1).

[0068] Examples of the negative electrode active material include: carbon, such as non-graphitized carbon and graphitic carbon; metal composite oxides, such as Li x Fe2O3 (0 ≤ x ≤ 1), Li x WO2 (0 ≤ x ≤ 1), Sn x Me 1-x Me’ y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, Groups 1, 2 and 3 of the periodic table, halogens; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8); lithium metal; lithium alloy; silicon alloy; tin alloy; metal oxides, such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4 and Bi2O5; conductive polymers, such as polyacetylene; and Li-Co-Ni type materials).

[0069] Based on the total weight of the mixture containing the positive electrode active material, the addition amount of the conductive material is usually 1 to 30% by weight. Such conductive materials are not particularly limited as long as they have conductivity and do not cause chemical changes in the battery, and examples thereof include: graphite, such as natural graphite and artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black and summer black; conductive fibers, such as carbon fiber and metal fiber; metal powders, such as carbon fluoride, aluminum and nickel powders; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; and conductive materials such as polyphenylene derivatives, etc.

[0070] Based on the total weight of the mixture containing the positive electrode active material, the addition amount of the binder as a component that helps the adhesion between the active material and the conductive material and the adhesion to the current collector is 1 to 30% by weight. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber and various copolymers thereof, etc.

[0071] The present invention also provides a method for manufacturing the current collector as described above.

[0072] Figure 4 This is a flowchart illustrating the sequence of methods for manufacturing the current collector according to the present invention. Figure 5 This is a schematic diagram illustrating the sequence and variations of the manufacturing method of the current collector of the present invention.

[0073] refer to Figure 4 and 5 The method for manufacturing the current collector of the present invention includes: depositing metal on at least one surface of a base film made of polymer material to form a deposited layer (S1); pulverizing and mixing the base film on which the deposited layer is formed, and then extruding the base film for the first time to manufacture a polymer-metal composite material (S2); and extruding the polymer-metal composite material to form a polymer film layer, wherein the fibrous or plate-like metal material is oriented in one direction in the polymer matrix (S3).

[0074] According to the current collector manufacturing method of the present invention, a polymer-metal composite material is manufactured by extruding a base film made of polymer material on which a metal deposition layer is formed, and the polymer-metal composite material is extruded again, thereby manufacturing a polymer-metal composite current collector with improved mechanical properties.

[0075] Figures 6 to 8 This is a schematic diagram illustrating each process in the manufacturing method of the current collector of the present invention.

[0076] and Figure 5 Let's refer to each other. Figures 6 to 8 First, a base membrane 30 made of polymer material is prepared. The base membrane 30 is the material constituting the polymer matrix of the current collector of the present invention, and can be made of at least one selected from polyolefin resins, polyamide resins, polyester resins, and poly(meth)acrylate resins. Details regarding the resin are the same as described above.

[0077] Prepare a base membrane 30, and deposit metal on the base membrane 30 to form a deposition layer 40, such as... Figure 5As shown. The deposited layer can be formed on at least one surface of the base film. The deposited layer 40 can be made of at least one metal material selected from the group consisting of aluminum, copper, indium, titanium, tin, nickel, iron, tungsten, chromium, cobalt, gold, and silver, which is the current collector of the present invention. More specifically, as the metal material, a metal with a melting point higher than the temperature set when extruding the base film (the base film on which the deposited layer is formed) described later can be used, such as aluminum, copper, titanium, nickel, tungsten, and iron. This is because, if the melting point is lower than the set temperature, the metal may not form a plate-like or fibrous shape as it melts and moves, but may form a spherical shape instead. For example, the melting point of the metal material can be equal to or greater than 200°C, specifically 600°C, more specifically 800°C.

[0078] In this invention, metal can be coated onto the base membrane 30 to achieve a nanometer-scale thickness by depositing metal on the base membrane 30. Similarly, compared to simply dispersing metal particles within the membrane, forming a deposition layer 40 on the base membrane 30 allows for better adhesion of the metal particles to the base membrane 30. The deposition layer can be formed over the entire base membrane or on a portion thereof.

[0079] At this point, the thickness of the deposited layer 40 can be 50 to 400 nm, 100 to 350 nm, or 150 to 300 nm, and the thickness of the base film 30 can be 20 to 400 μm, 50 to 350 μm, or 100 to 300 μm. When the thickness of the deposited layer is less than the above range or the thickness of the base film exceeds the above range, the volume of the deposited layer is too small compared to the base film, making it difficult to meet the intended physical properties of the current collector. Conversely, if the thickness of the deposited layer exceeds the above range or the thickness of the base film is less than the above range, cracks may occur on the deposited layer, increasing manufacturing costs and making it difficult to achieve lightweight current collectors.

[0080] Furthermore, the volume ratio of the deposited layer 40 to the base membrane 30 can be 0.5:99.5 to 10:90, 0.5:99.5 to 5:95, 0.5:99.5 to 3:97, or 0.5:99.5 to 1.5:98.5. When the above numerical ranges are met, a sufficient amount of metal material can be included in the polymer membrane layer described later, while simultaneously making the current collector lightweight. The volume ratio can be calculated using the thickness and area of ​​the base membrane and the deposited layer. When the volume of the deposited layer is excessively smaller than the volume of the base membrane, it is difficult to improve the mechanical properties; when the volume of the deposited layer is too large, the manufacturing cost increases, and cracks may occur on the deposited layer.

[0081] Furthermore, the deposited layer 40 can have a structure in which two or more different metal layers are stacked together. Similarly, by forming the deposited layer 40 into a structure with two or more layers composed of different metals, the metal material in the polymer film layer can include two or more different types of metals during the manufacture of the current collector. Therefore, the strength, flexibility, and processability of the polymer film layer can be set to the desired level. At this time, the thickness and metal type of each layer constituting the deposited layer can be selected with consideration of the strength, flexibility, and processability of the polymer film layer. For example, to enhance the strength of the polymer film layer, a metal material with relatively high strength can be used, while to enhance flexibility and processability, a metal material with relatively high ductility or a metal material with a low melting point can be used.

[0082] The deposited layer 40 can be formed by evaporation, sputtering, or aerosol deposition. Evaporation refers to deposition in an atmospheric pressure or high vacuum chamber (5x10⁻⁶). -5 ~1x10 -7 In Torr, a method uses an electron beam or filament to deposit target material onto an object through evaporation or sublimation. Sputtering, on the other hand, refers to a method that uses plasma generated by flowing a gas such as argon in a vacuum chamber and applying a voltage to deposit target material onto an object.

[0083] Specifically, when using the evaporation method, it can be done under a high vacuum (5x10). -5 ~1x10 -7 A voltage is applied to the target located in a crucible and evaporation boat containing tungsten (W) or molybdenum (Mo) at a pressure of Torr or atmospheric pressure, or the power of the electron beam is increased, and then evaporation is carried out at a rate of 0.1 nm / sec to 10 nm / sec.

[0084] Alternatively, when using sputtering, the deposition process can be carried out at eutectic pressures of 1 to 100 mTorr, 1 to 75 mTorr, or 1 to 50 mTorr. Furthermore, sputtering can be performed in a chamber containing a sputtering gas (e.g., argon (Ar) or helium (He)) or a reactive gas (e.g., oxygen, nitrogen, or mixtures thereof). Further details regarding the deposition process are known to those skilled in the art and will therefore be omitted in their detailed description.

[0085] Here, the deposited layer can be formed using a roll-to-roll process, and can be produced by a material with... Figure 6 The deposition unit 100 of the structure shown is used. For example, as... Figure 6 As shown, when the base film unwound from the unwinding roller 110 moves along the surface of the drive roller 120, metal elements evaporated from the metal supply source 130 located at predetermined intervals can be deposited on the base film 30. The base film 30, on which the deposition layer 40 is formed, can then be wound onto the rewinding roller 140.

[0086] Once deposition is complete, a base film with the deposited layer formed on it is extruded to manufacture the polymer-metal composite material 50. Specifically, as... Figure 7 As shown, the base film 30 is pulverized and mixed before extrusion. At this point, the base film 30, on which the deposited layer has formed, is pulverized, mixed, and melted before extrusion. Melting can be carried out at temperatures above 180°C, specifically, even above 200°C. Alternatively, a hot press melter can be used.

[0087] Subsequently, the molten material obtained through the melting process is extruded to form a polymer-metal composite material. This process can be performed using a twin-screw extruder 200. In the case of a twin-screw extruder, the metal material can be easily dispersed within the polymer matrix. During this process, the internal metal can be formed into a plate-like or fibrous form.

[0088] like Figure 8 As shown, during the manufacture of the polymer-metal composite material 50, the polymer-metal composite material 50 is extruded again. At this time, after extruding the polymer-metal composite material 50, the extruded material can be formed into a film, and when the polymer-metal composite material 50 is extruded in the form of a film, the plate-like or fibrous metal material is again oriented along the length direction (extrusion direction) of the film. Here, orientation along the length direction means that the plate-like or fibrous metal material is arranged at an angle within a predetermined range with respect to the length direction axis and the thickness direction axis as described above.

[0089] The extrusion of the polymer-metal composite material 50 can be carried out after the polymer-metal composite material 50 has been crushed, mixed and melted, and the extrusion can be carried out by a single-screw extruder 300. By using a single-screw extruder, the polymer-metal composite material can be uniformly discharged, and the metal material inside the polymer-metal composite material can be oriented in one direction along the extrusion direction.

[0090] The extruded polymer film can then undergo a cooling process, which can be carried out by placing the polymer film at room temperature or by using a separate cooler.

[0091] In another example, the method for manufacturing the current collector of the present invention may further include forming a metal layer on at least one surface of the polymer film layer manufactured by the above method.

[0092] For example, the metal layer can be formed by deposition and has a thickness of less than 1 μm or less than 0.5 μm. Therefore, the increase in electrode volume and weight can be minimized while supplementing the mechanical rigidity of the current collector and improving its conductivity.

[0093] The present invention will be described in detail below with reference to embodiments. However, embodiments of the present invention can be modified in various other ways, and the scope of the invention should not be construed as limited to the embodiments described below. The embodiments of the present invention are provided to provide a more complete description of the invention to those skilled in the art.

[0094] Example 1-1

[0095] Aluminum was deposited on a 210 μm thick polymethyl methacrylate (PMMA) resin film to form a 100 nm thick deposited layer. The base film with the deposited layer was then pulverized, and the pulverized base film was mixed at 180 °C and 50 rpm and extruded using a twin-screw extruder to produce a polymer-metal composite material. The polymer-metal composite material was then extruded again using a single-screw extruder to form a 100 μm thick polymer film layer.

[0096] Examples 1-2

[0097] The polymer film was formed in the same manner as in Examples 1-1, except that 100 nm of indium was deposited on the base film.

[0098] Comparative Example 1

[0099] Without forming a deposited layer, a PMMA resin film is extruded in the same manner as in Examples 1-1 to form a polymer film layer.

[0100] Experimental Example 1

[0101] The elastic modulus and elongation at break of the polymer films of Examples 1-1 and 1-2 and Comparative Example 1 were measured. The elastic modulus and elongation at break were measured using a universal testing machine (UTM) according to the measurement method of ASTM D 882. The results are shown in Table 1 below.

[0102] [Table 1]

[0103] Example 1-1 12.0 24 Examples 1-2 9.5 20 Comparative Example 1 1.1 13

[0104] Referring to Table 1, it can be seen that the mechanical properties of the membrane obtained by depositing metal on a base membrane, extruding the base membrane to form a polymer-metal composite material, and then extruding the composite material again are superior to those of Comparative Example 1. This is because the fibrous or plate-like metal material inside the membrane has already been oriented along the extrusion direction.

[0105] Example 2-1

[0106] Aluminum was deposited to a thickness of 300 nm on a 210 μm thick polypropylene (PP) resin film as a base film, thus forming a deposited layer. At this point, the metal content in the total volume of the base film on which the deposited layer was formed was 1.5%. The base film with the deposited layer was then pulverized, and the pulverized base film was mixed at 180°C and 50 rpm. The mixture was then extruded using a twin-screw extruder to produce a polymer-metal composite material. This polymer-metal composite material was then extruded again using a single-screw extruder to form a polymer film layer with a thickness of 100 μm.

[0107] Copper (Cu) was deposited on both surfaces of the polymer film to a thickness of 150 nm using an electron beam evaporator, thereby creating a current collector on which a metal layer was formed.

[0108] Examples 2-2 to 2-4

[0109] As shown in Table 2 below, metal is deposited on the PP base film to have a predetermined thickness, and then the current collector is manufactured in the same manner as in Example 2-1.

[0110] Examples 2-5

[0111] As shown in Table 2, indium (In) and aluminum (Al) were deposited on a polypropylene (PP) resin film as the base film to have thicknesses of 20 nm and 300 nm, respectively, and then the current collector was manufactured in the same manner as in Example 2-1.

[0112] Comparative Example 2-1

[0113] A current collector is manufactured by extruding a PP resin film in the same manner as in Example 2-1 without forming a deposited layer.

[0114] Comparative Example 2-2

[0115] The current collector was manufactured in the same manner as in Example 2-1, except that aluminum was deposited on the base film to have a thickness of 20 nm.

[0116] Experimental Example 2

[0117] The polymer films prepared according to Examples 2-1 and 2-5 and Comparative Example 2-1 were inserted into a FESEM (JEOL JSM-7610F) to obtain longitudinal cross-sectional SEM images and energy-dispersive X-ray spectroscopy (EDS) images, which are shown in Figures 1-2. Figure 9 (Example 2-1) Figure 10 (Examples 2-5) and Figure 11 (Comparative Example 2-1). In Figures 9 to 11In the image, (a) and (b) are SEM images obtained by magnifying the samples by 3000 and 500 times, respectively. Figure 9 (c) shows a photograph illustrating the aluminum distribution using EDS. (via EDS) Figure 10 (c) shows the distribution of aluminum metal. Figure 10 (d) shows the distribution of indium metal. Furthermore, in Figures 9 to 11 In the diagram, the line formed in region A is a Cu metal layer deposited on the polymer film.

[0118] Experimental Example 3

[0119] The complex modulus was measured using a Q800 (TA Instruments) as a dynamic mechanical analysis (DMA) device at room temperature and 1 Hz while a strain of 0.1% was applied to the sample. The results are shown in Table 2 below.

[0120] [Table 2]

[0121]

[0122] refer to Figures 9 to 11 The current collector of embodiments of the present invention may include a fibrous or plate-like metal material (B) with a thickness or cross-sectional diameter of nm units and a length of μm units. Referring to Table 2, it can be seen that the current collector of the embodiments obtained by re-extruding the polymer-metal composite material formed by depositing metal on a film at a predetermined volume ratio and extruding the film has better mechanical properties than that of Comparative Examples 2-1. This is because, as Figure 9 and 10 As shown, the fibrous or plate-like metal material inside the membrane has been oriented along the extrusion direction.

[0123] Furthermore, in Comparative Example 2-2, where the thickness of the deposited layer is smaller compared to the Examples, the physical properties are reduced compared to the Examples because the metal material has not yet fully formed inside the polymer film.

[0124] Here, in Examples 2-3 and 2-4 using indium (In), processability is improved due to indium's low melting point (160°C), but the physical properties of the current collector are reduced compared to the case where aluminum or nickel, whose melting points are higher than the temperature set during extrusion, are lower because, as Figure 10 As shown, molten indium during the extrusion process may exist in both spherical and linear forms as it moves. In this case, the physical properties of the current collector can be further improved by forming the deposited layer as a two-layer structure, and further forming a deposited layer made of a different metallic material (e.g., Al).

[0125] The above description merely illustrates the technical concept of the present invention, and those skilled in the art can make various modifications and variations without departing from the basic characteristics of the invention. Therefore, the accompanying drawings disclosed herein are not intended to limit the technical concept of the invention, but rather to describe it, and the scope of the technical concept of the invention is not limited by these drawings. The scope of protection of the present invention should be interpreted by the following claims, and all technical concepts within the scope of the claims should be interpreted as included within the scope of the present invention.

[0126] On the other hand, this specification uses terms such as up, down, left, right, front, and back to indicate direction, but it is obvious that these terms are only for ease of description and may change depending on the position of the object or the observer.

[0127] [Description of reference numerals in the attached figures]

[0128] 1, 2: Current collector

[0129] 10: Polymer film layer

[0130] 11: Polymer matrix

[0131] 12: Metallic Materials

[0132] 20: Metal layer

[0133] 30: Base membrane

[0134] 40: Sedimentary layer

[0135] 50: Polymer-metal composites

[0136] 100: Sedimentary unit

[0137] 110: Unwinding roller

[0138] 120: Drive roller

[0139] 130: Metal Supply Source

[0140] 140: Rewinding roller

[0141] 200: Twin-screw extruder

[0142] 300: Single-screw extruder

Claims

1. A current collector comprising a composite polymer film layer, wherein The composite polymer film layer includes: Polymer matrix; and Fiber-like or plate-like metallic materials dispersed in the polymer matrix, and The metal material is oriented in one direction such that more than 80% of the entire metal material has the following angles: the angle between the metal material and the length axis of the polymer film is less than 20°, and the angle between the metal material and the thickness axis of the polymer film is between 70° and 90°.

2. The current collector of claim 1, wherein, The metallic material is selected from at least one of the following groups: aluminum, copper, indium, titanium, tin, nickel, iron, tungsten, chromium, cobalt, gold, and silver. The polymer matrix is ​​made of at least one selected from polyolefin resin, polyamide resin, polyester resin and poly(meth)acrylate resin.

3. The current collector of claim 1, wherein, The fibrous metal material has a cross-sectional diameter of 10 to 500 nm and a length of 0.5 to 200 μm.

4. The current collector of claim 1, wherein, The thickness of the plate-shaped metal material is 10 to 500 nm, and the width and length of the plate-shaped metal material are 0.5 to 200 μm, respectively.

5. The current collector of claim 1, wherein, The metallic material contains two or more different types of metals.

6. The current collector of claim 1, wherein, The thickness of the polymer film is 10 to 200 μm.

7. The current collector according to claim 1, further comprising a metal layer formed on at least one surface of the polymer film layer and having a thickness of less than 1 μm.

8. A method for manufacturing a current collector, the method comprising: A deposition layer is formed by depositing metal on at least one surface of a base film made of polymer material; The base film on which the deposited layer is formed is crushed and mixed, and then the base film is extruded for the first time to produce a polymer-metal composite material; as well as The polymer-metal composite material is extruded to form a polymer film in which fibrous or plate-like metal material is oriented in one direction within a polymer matrix.

9. The method of claim 8, wherein, The metal is at least one selected from the group consisting of aluminum, copper, indium, titanium, tin, nickel, iron, tungsten, chromium, cobalt, gold, and silver. The base membrane is made of at least one selected from polyolefin resin, polyamide resin, polyester resin and poly(meth)acrylate resin.

10. The method according to claim 8, wherein, The thickness of the deposited layer is 50 to 400 nm, and the thickness of the base film is 20 to 400 μm.

11. The method according to claim 8, wherein, The volume ratio of the deposited layer to the base film is from 0.5:99.5 to 10:

90.

12. The method according to claim 8, wherein, The deposited layer has a structure in which two or more different metal layers are stacked together.

13. The method according to claim 8, wherein, The base film on which the deposited layer is formed is extruded by a twin-screw extruder.

14. The method according to claim 8, wherein, The extrusion of polymer-metal composites is carried out using a single-screw extruder.

15. The method of claim 8, further comprising: A metal layer is formed on at least one surface of the polymer film.

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