Patent Application
20240186528
The present disclosure relates to a current collector and a method of manufacturing the same, and more particularly, to a current collector including a polymer film and a method of manufacturing the same.
Recently, secondary batteries capable of charging and discharging have been widely used as energy sources of wireless mobile devices. In addition, the secondary battery has attracted attention as an energy source of an electric vehicle, a hybrid electric vehicle, etc., which are proposed as a solution for air pollution of existing gasoline vehicles and diesel vehicles using fossil fuel. Therefore, the types of applications using the secondary battery are currently much diversified due to the advantages of the secondary battery, and it is expected that the secondary battery will be applied to many fields and products in the future.
Such secondary batteries may be classified into lithium ion batteries, lithium ion polymer batteries, lithium polymer batteries, etc., depending on the composition of the electrode and the electrolyte, and among them, the amount of use of lithium-ion polymer batteries that are less likely to leak electrolyte and are easy to manufacture is on the increase. In general, secondary batteries are classified depending on the shape of a battery case, into cylindrical batteries and prismatic batteries in which an electrode assembly is embedded in a cylindrical or rectangular metal can, and pouch-type batteries in which the electrode assembly is embedded in a pouch-type case of an aluminum laminate sheet. The electrode assembly built into the battery case is composed of a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and is a power generating element capable of charging and discharging. The electrode assembly is classified into a jelly-roll type wound with a separator interposed between the positive electrode and the negative electrode which are long sheet-shaped and are coated with active materials, and a stack type in which a plurality of positive electrodes and negative electrodes of a predetermined size are sequentially stacked while a separator is interposed therebetween.
These electrodes may be manufactured by forming an electrode mixture layer by coating an electrode slurry containing an electrode active material on a current collector and drying the electrode slurry. At this time, a general current collector may be made of metal having excellent electrical conductivity such as copper or aluminum, a current collector, which is obtained by complexing a polymer film with metal, is being developed for weight-lightening of the current collector.
However, in the case of a current collector, which is obtained by complexing such a polymer with metal, the elastic modulus of a general polymer film is in a range of 0.1 to 5 GPa, which is much lower than that of copper (117 GPa) or aluminum (69 GPa). As such, the thickness of the polymer-metal complex current collector should be set to be 10 times or more greater than that of a general current collector in order to impart physical properties similar to those of a metal current collector. This causes a problem that the volume and mass of the electrode increases.
The present disclosure is believed to solve at least some of the above problems. For example, an aspect of the present disclosure provides a polymer-metal complex current collector having improved mechanical properties, and a method of manufacturing the same.
A current collector according to the present disclosure is a current collector including a complex polymer film layer. The complex polymer film layer includes: a polymer matrix; and fiber-shaped or plate-shaped metal materials which are dispersed in the polymer matrix, and the metal materials are oriented in one direction.
In a specific example, the metal material may be at least one selected from the group consisting of aluminum, copper, indium, titanium, tin, nickel, iron, tungsten, chrome, cobalt, gold and silver, and the polymer film may be made of at least one selected from the group consisting of a polyolefin resin, a polyamide resin, a polyester resin, and a polyalkyl(meth)acrylate resin.
In a specific example, a diameter of a cross-section of the fiber-shaped metal material may be in a range of 10 to 500 nm, and a length of the cross-section of the fiber-shaped metal material may be in a range of 0.5 to 200 μm.
In a specific example, a thickness of the plate-shaped metal material may be in a range of 10 to 500 nm, and a width and a length of the plate-shaped metal material may be in a range of 0.5 to 200 μm, respectively.
In one example, the metal material may contain two or more different kinds of metal.
In a specific example, the angle between the metal material and the longitudinal direction axis of the polymer film layer is equal to or less than 20°, and the angle between the metal material and the thickness direction axis of the polymer film layer is in the range of 70 to 90°.
In a specific example, a thickness of the polymer film layer may be in a range of 10 to 200 μm.
In another example, the current collector may further include a metal layer which is formed on at least one surface of the polymer film and has a thickness of 1 μm or less.
Further, the present disclosure provides a method of manufacturing the above-described current collector.
The method of manufacturing a current collector according to the present disclosure includes: forming a deposition layer by depositing a metal on at least one surface of a base film made of a polymer material; manufacturing a polymer-metal complex material by pulverizing and mixing the base film having the deposition layer formed thereon and then first-extruding the base film; and forming a polymer film layer in which fiber-shaped or plate-shaped metal materials are oriented in one direction in a polymer matrix, by extruding the polymer-metal complex material.
In a specific example, the metal may be at least one selected from the group consisting of aluminum, copper, indium, titanium, tin, nickel, iron, tungsten, chrome, cobalt, gold and silver, and the base film may be made of at least one selected from the group consisting of a polyolefin resin, a polyamide resin, a polyester resin, and a polyalkyl(meth)acrylate resin.
In a specific example, a thickness of the deposition layer may be in a range of 50 to 400 nm, and a thickness of the base film may be in a range of 20 to 400 μm.
At this time, a volume ratio of the deposition layer to the base film may be in a range of 0.5: 99.5 to 10: 90.
In one example, the deposition layer may have a structure where two or more different metal layers are laminated.
In a specific example, the base film having the deposition layer formed thereon may be extruded by a twin-screw extruder.
Further, extrusion of a polymer-metal complex material may be performed by a single-screw extruder.
In another example, the method of manufacturing a current collector according to the present disclosure may further include forming a metal layer on at least one surface of the polymer film layer.
According to the present disclosure, it is possible to improve mechanical properties of the current collector including a polymer film layer by dispersing fiber-shaped or plate-shaped metal materials oriented in one direction in the polymer film layer.
Hereinafter, the present disclosure will be described in detail with reference to the drawings. The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may properly define the concept of the terms in order to best describe the disclosure. The terms and words should be construed as meaning and concept consistent with the technical idea of the present disclosure.
In this application, it should be understood that terms such as “include” or “have” are intended to indicate that there is a feature, number, step, operation, component, part, or a combination thereof described on the specification, and they do not exclude in advance the possibility of the presence or addition of one or more other features or numbers, steps, operations, components, parts or combinations thereof. Also, when a portion such as a layer, a film, an area, a plate, etc. is referred to as being “on” another portion, this includes not only the case where the portion is “directly on” the another portion but also the case where further another portion is interposed therebetween. On the other hand, when a portion such as a layer, a film, an area, a plate, etc. is referred to as being “under” another portion, this includes not only the case where the portion is “directly under” the another portion but also the case where further another portion is interposed therebetween. In addition, to be disposed “on” in the present application may include the case disposed at the bottom as well as the top.
Further, in the present disclosure, a longitudinal direction of a polymer film or a current collector means a direction in which a polymer is extruded at the time of forming a polymer film layer, or a direction (MD direction, x-axis direction) in which a film is moved at the time of manufacturing and processing a current collector. The width direction means a direction perpendicular to (y-axis direction) the longitudinal direction on the surface formed by a film layer.
Hereinafter, the present disclosure will be described in detail with reference to the drawings.
A current collector according to the present disclosure is a current collector including a complex polymer film layer. The complex polymer film layer includes: a polymer matrix; and fiber-shaped or plate-shaped metal materials which are dispersed in the polymer matrix, and the metal materials are oriented in one direction.
As described above, in the case of a current collector, which is obtained by complexing a polymer with metal, the physical properties of a general polymer film are much lower than those of a metal current collector. As such, the thickness of the polymer-metal complex current collector should be set to be 10 times or more greater than that of a general current collector in order to impart physical properties similar to those of a metal current collector. This causes a problem that the volume and mass of the electrode increases.
According to the present disclosure, it is possible to improve mechanical properties of the current collector including a polymer film layer by dispersing fiber-shaped or plate-shaped metal materials in the polymer film layer.
Referring to
As illustrated in
A material, which functions as a matrix in which metal materials to be described later are dispersed, provides flexibility to the current collector, and has a rigidity sufficient to be used as the current collector, may be used as the polymer material which is used for the polymer matrix 11. For example, the polymer film may be made of at least one selected from the group consisting of a polyolefin resin, a polyamide resin, a polyester resin, and a polyalkyl(meth)acrylate resin.
At this time, the polyolefin resin may be high-density, intermediate-density, low-density, or linear low-density polyethylene, crystalline polypropylene, non-crystalline polypropylene, or polybutylene.
The polyamide resin may be nylon 6, nylon 6,6, nylon 610, or nylon 12.
The polyester resin may be polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or polyethylene naphthalate.
The polyalkyl(meth)acrylate resin may be polymethyl methacrylate, polymethyl acrylate, polyethyl acrylate, or polybutyl acrylate.
The metal material 12 has a minimum nanometer level size and is uniformly dispersed in the polymer matrix 11.
More specifically, the metal material 12 may be fiber-shaped and/or plate-shaped. Herein, the fiber shape indicates that the metal material 12 in the polymer matrix 11 has a thin fiber shape as shown in
Namely, the metal material 12 has a shape which is long in one direction. The metal material 12 improves mechanical properties of the polymer film layer 10 by being oriented in one direction in the polymer matrix 11. Specifically, the metal material 12 may be oriented in a longitudinal direction (x-axis direction) of the polymer film layer 10 as illustrated in
The metal material may be at least one selected from the group consisting of aluminum, copper, indium, titanium, tin, nickel, iron, tungsten, chrome, cobalt, gold and silver, but there is no limitation to the type as long as it can be easily processed together with a film and can improve mechanical properties of the polymer film layer. More specifically, a metal having a melting point, which is higher than a temperature which is set at the time of extruding materials constituting a polymer matrix to be described later, may be used as the metal material, such as aluminum, copper, titanium, nickel, tungsten, and iron. This is because, in the case that the melting point is lower than the temperature which is set at the time of melting and extruding a polymer material, metal may not be able to form a plate shape or a fiber shape and may form a spherical shape. For example, the melting point of the metal material may be equal to or greater than 200° C., specifically 600° C., and more specifically 800° C.
If the metal material 12 is fiber-shaped, the diameter of the cross-section of the metal material 12 may be in a range of 10 to 500 nm, in a range of 100 to 400 nm, or in a range of 150 to 350 nm, and the length of the metal material 12 may be in a range of 0.5 to 200 μm, in a range of 0.5 to 150 μm, or in a range of 0.5 to 100 μm.
Further, if the metal material 12 is plate-shaped, the thickness of the metal material 12 may be in a range of 10 to 500 nm, in a range of 100 to 400 nm, or in a range of 150 to 350 nm, and the width and the length of the metal material 12 may be in a range of 0.5 to 200 μm, in a range of 0.5 to 150 μm, or in a range of 0.5 to 100 μm.
When the size (diameter, thickness or length) of the metal material is excessively small, the effects of increasing physical properties are not significant, and when the size the metal materials is excessively large, the thickness of the deposition layer formed on the base film should become thick as will be described later. In this case, a crack may be generated on the deposition layer, and the costs may increase.
Likewise, the metal material 12 may be easily bonded on the polymer matrix 11 in the polymer matrix 11 by dispersing fiber-shaped or plate-shaped metal materials 12 having a nanometer level size in the polymer matrix 11, and it is possible to prevent the metal material 12 from being discharged to the outside of the polymer matrix 11.
Further, the metal material 12 may improve longitudinal direction mechanical properties of the polymer film layer 10 by being oriented in the longitudinal direction (x-axis direction) of the polymer film layer 10 as described above. Specifically, the angle between the metal material 12 and the longitudinal direction axis (x-axis) of the polymer film layer 10 may be 20° or less, 15° or less, or 10° or less, and the angle between the metal material 12 and the thickness direction axis (z-axis) may be in the range of 70 to 90°, or 80 to 90°. Further, 80% or more, 90% or more, or 95% or more of the entire metal material may have the above orientation angle. When the orientation degree of the metal material 12 is in the above range, the mechanical properties of the polymer film layer 10 may be effectively improved.
In one example, the metal material 12 may contain two or more different kinds of metal. This includes both a case that different metal materials each is made of a different metal and a case that one metal material contains two or more kinds of metals. As such, it is possible to set the strength, flexibility and processability of the polymer film layer at a desired level. At this time, the type and content ratio (e.g., volume ratio) of the metal material may be selected in consideration of strength, flexibility and processability of the polymer film layer intended to be achieved. For example, in order to enhance the strength of the polymer film layer, a metal material having a relatively large strength may be used, and in order to enhance flexibility and processability, a metal material having a relatively large ductility, or a metal material having a relatively low melting point may be used.
Further, a thickness of the polymer film layer may be in a range of 10 to 200 μm, and specifically in a range of 50 to 150 μm. Namely, the current collector 1 according to the present disclosure has a thickness similar to that of a general metal current collector, and may show mechanical properties similar to those of the metal current collector. When the thickness of the polymer film layer 10 is less than 10 μm, it is difficult to show mechanical properties because the thickness of the current collector is excessively small, and when the thickness of the polymer film layer 10 exceeds 200 μm, the volume and the weight of the electrode and the battery cell increase because the thickness of the current collector excessively increases.
Referring to
For example, the metal layer 20 may be formed by deposition and has a thin thickness of 1 μm or less or 0.5 μm or less. As such, it is possible to minimize the increase in the volume and weight of the electrode while supplementing the mechanical rigidity of the current collector 2 and improving the electrical conductivity of the current collector 2. Further, the metal layer may have a thickness of 50 nm or more, 100 nm or more, or 200 nm or more.
Further, the present disclosure provides an electrode including a current collector as described above.
The electrode includes an electrode mixture layer formed on at least one surface of the above-described current collector. The electrode mixture layer is formed by coating an electrode slurry including an electrode active material, a conductive material and a binder on a current collector. The electrode active material may be a positive electrode active material or a negative electrode active material.
In the present disclosure, the positive electrode active material is a material capable of causing an electrochemical reaction and a lithium transition metal oxide, and contains two or more transition metals. Examples thereof 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; lithium nickel oxide represented by the formula LiNi1-yMyO2 (wherein 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); lithium nickel cobalt manganese composite oxide represented by the formula Li1+zNibMncCo1-(b+c+d)MdO(2-e)Ae such as Li1+zNi1/3Co1/3Mn1/3O2, Li1+zNi0.4Mn0.4Co0.2O2 etc. (wherein −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); olivine-based lithium metal phosphate represented by the formula Li1+xM1-yM′yPO4-zXz (wherein 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).
Examples of the negative electrode active material include carbon such as non-graphitized carbon and graphite carbon; metal complex oxide such as LixFe2O3(0≤x≤1), LixWO2(0≤x≤1), SnxMe1-xMe′yOz (Me: Mn, Fe, Pb, Ge; Me′: Al, B, P, Si, groups 1, 2, and 3 of the periodic table, halogen; 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-based materials.
The conductive material is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture including the positive electrode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing a chemical change 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 powder; conductive whiskey such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives and the like.
The binder is added in an amount of 1 to 30% by weight, on the basis of the total weight of the mixture containing the positive electrode active material, as a component that assists in bonding between the active material and the conductive material and bonding to the current collector. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.
The present disclosure also provides a method for manufacturing a current collector as described above.
Referring to
According to the method of manufacturing a current collector of the present disclosure, it is possible to manufacture a polymer-metal complex current collector having improved mechanical properties by making a polymer-metal complex material by extruding a base film made of a polymer material having a metal deposition layer formed thereon, and extruding again the polymer-metal complex material.
Referring to
The base film 30 is prepared, metal is deposited on the base film 30 to thereby form a deposition layer 40 as shown in
In the present disclosure, it is possible to coat metal on the base film to have a nanometer level thickness by depositing the metal on the base film 30. Likewise, metal particles are better boned on the base film 30 by forming a deposition layer 40 on the base film 30, compared to the case of simply dispersing metal particles at the inside of the film. The deposition layer may be formed on the whole or part of the base film.
At this time, the thickness of the deposition layer 40 may be in a range of 50 to 400 nm, 100 to 350 nm, or 150 to 300 nm, and the thickness of the base film 30 may be in a range of 20 to 400 μm, 50 to 350 μm, or 100 to 300 μm. When the thickness of the deposition layer is less than the above range or the thickness of the base film exceeds the above range, it is difficult to satisfy physical properties of the current collector intended to be achieved because the volume of the deposition layer is excessively small, compared to the base film. On the contrary, if the thickness of the deposition layer exceeds the above range or the thickness of the base film is less than the above range, a crack may be generated on the deposition layer, the manufacturing costs increase, and it is difficult to achieve weight-lightening of the current collector.
Further, the volume ratio of the deposition layer 40 to the base film 30 may be in a range of 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 range is satisfied, it is possible to include a sufficient amount of metal materials in the polymer film layer to be described later while weight-lightening the current collector. The volume ratio may be calculated using the thickness and area of the base film and the deposition layer. When the volume of the deposition layer is excessively smaller than that of the base film, it is difficult to improve mechanical properties, and when the volume of the deposition layer is excessively large, the manufacturing costs increase, and a crack may be generated on the deposition layer.
Further, the deposition layer 40 may have a structure where two or more different metal layers are laminated. Likewise, it is possible to allow the metal material in the polymer film layer to include two or more different kinds of metal at the time of manufacturing a current collector by forming the deposition layer 40 to have a structure of 2 or more layers composed of different metals. As such, it is possible to set the strength, flexibility and processability of the polymer film layer at a desired level. At this time, the thickness of each layer constituting the deposition layer and type of the metal may be selected in consideration of strength, flexibility and processability of the polymer film layer. For example, in order to enhance the strength of the polymer film layer, a metal material having a relatively large strength may be used, and in order to enhance flexibility and processability, a metal material having a relatively large ductility, or a metal material having a low melting point may be used.
The deposition layer 40 may be formed by an evaporation method, a sputtering method, or an aerosol deposition method. The evaporation method refers to a method of depositing target materials on an object by evaporation or sublimation using an electron beam or an electric filament in a normal pressure or high-vacuum chamber (5×10−5˜1×10−7 Torr). Further, the sputtering method refers to a method of depositing target materials on an object by plasma which is generated by allowing gas such as argon to flow in a vacuum chamber and applying voltage.
Specifically, when the evaporation method is used, voltage may be applied to the target positioned at the crucible and the evaporation boat including tungsten (W) or molybdenum (Mo) at a high-vacuum state (5×10−5˜1×10−7 Torr) or a normal pressure, or power of the electron beam was increased, and it was then performed under the evaporation speed condition of 0.1 nm/sec. to 10 nm/sec.
Alternatively, when the sputtering method is used, it can be performed under eutectic pressure of 1 to 100 mTorr, 1 to 75 mTorr, or 1 to 50 mTorr. Further, the sputtering can be performed in a chamber including sputtering gas such as argon (Ar) or helium (He) or reactive gas such as oxygen, nitrogen, or mixed gas thereof. Other details about the deposition method are known to those of ordinary skill in the art, and thus detailed description thereof will be omitted.
Herein, the deposition layer may be formed by a roll-to-roll process and may be performed by a deposition unit 100 having a structure as shown in
When the deposition is completed, a polymer-metal complex material 50 is manufactured by extruding the base film having the deposition layer formed thereon. Specifically, as shown in
Thereafter, a polymer-metal complex material is formed by extruding molten materials obtained through the melting process. The process may be extruded by the twin-screw extruder 200. In the case of twin-screw extruder, metal materials may be easily dispersed in the polymer matrix. In this process, the metal inside may be formed in a plate or fiber shape.
When the polymer-metal complex material 50 is manufactured, the polymer-metal complex material 50 is extruded again as shown in
The extrusion of the polymer-metal complex material 50 may be performed after pulverizing, mixing and melting the polymer-metal complex material 50, and the extrusion may be performed by a single-screw extruder 300. The polymer-metal complex material may be uniformly discharged, and the metal material inside the polymer-metal complex material may be oriented in one direction along the extruding direction by performing extrusion using a single-screw extruder.
Thereafter, the extruded polymer film may go through the cooling process, which may be performed by using a method of leaving the polymer film in a room temperature or using a separate cooler.
In another example, the method of manufacturing a current collector according to the present disclosure may further include forming a metal layer on at least one surface of the polymer film layer manufactured by the above-described method.
For example, the metal layer may be formed by deposition and has a thin thickness of 1 μm or less or 0.5 μm or less. As such, it is possible to minimize the increase in the volume and weight of the electrode while supplementing the mechanical rigidity of the current collector and improving the electrical conductivity of the current collector.
Hereinafter, the present disclosure will be described in detail with reference to examples. However, the embodiments according to the present disclosure may be modified into various other forms, and the scope of the present disclosure should not be construed as being limited to the examples described below. The examples of the present disclosure are provided to more fully describe the present disclosure to those skilled in the art.
A deposition layer was formed by depositing aluminum on a polymethyl methacrylate (PMMA) resin film having a thickness of 210 μm as a base film to have a thickness of 100 nm. A polymer-metal complex material was manufactured by pulverizing the base film having the deposition layer formed thereon and then mixing the pulverized base film at conditions of 180° C. and 50 rpm and extruding the mixture using a twin-screw extruder. A polymer film layer having a thickness of 100 μm was formed by extruding the polymer-metal complex material again using a single-screw extruder.
A polymer film layer was formed in the same manner as in the example 1-1 except that indium of 100 nm was deposited on the base film.
A polymer film layer was formed by extruding a PMMA resin film in the same manner as in the example 1-1 without forming a deposition layer.
The elastic modulus and fracture elongation rate of the polymer film layer according to the examples 1-1 and 1-2 and comparative example 1 were measured. The elastic modulus and the fracture elongation rate 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.
Referring to Table 1, it is seen that the mechanical properties of the film of the example, which is obtained by extruding again a polymer-metal complex material which has been formed by depositing metal on a base film and extruding the base film, are better than the mechanical properties of the comparative example 1. This is because the fiber-shaped or plate-shaped metal material inside the film has been oriented in the extruding direction.
A deposition layer was formed by depositing aluminum on a polypropylene (PP) resin film having a thickness of 210 μm as a base film to have a thickness of 300 nm. At this time, the ratio, by which metal is occupied in the total volume of the base film having the deposition layer formed thereon, was 1.5%. A polymer-metal complex material was manufactured by pulverizing the base film having the deposition layer formed thereon and then mixing the pulverized base film at conditions of 180° C. and 50 rpm and extruding the mixture. A polymer film layer having a thickness of 100 μm was formed by extruding the polymer-metal complex material again using a single-screw extruder.
A current collector having a metal layer formed thereon was manufactured by depositing copper (Cu) on two surfaces of the polymer film layer to have a thickness of 150 nm using an E-beam evaporator.
As shown in Table 2 below, after depositing metal on a PP base film to have a predetermined thickness, a current collector was manufactured in the same manner as in example 2-1.
As shown in Table 2, after depositing indium (In) and aluminum (Al) on a polypropylene (PP) resin film as a base film to have a thickness of 20 nm and 300 nm, respectively, a current collector was manufactured in the same manner as in example 2-1.
A current collector was manufactured by extruding a PP resin film in the same manner as in the example 2-1 without forming a deposition layer.
The current collector was manufactured in the same manner as in the example 2-1 except that aluminum was deposited on the base film to have a thickness of 20 nm.
SEM photographs and energy dispersive X-ray spectroscopy (EDS) photographs of a longitudinal cross-section were obtained by inserting the polymer film layer, which had been manufactured according to examples 2-1 and 2-5 and comparative example 2-1, into FESEM (JSM-7610F of JEOL company), and the photographs are shown in
A complex modulus was measured under conditions of a room temperature and a frequency of 1 Hz while applying strain of 0.1% to the specimen using Q800 (TA company) as a dynamic mechanical analysis (DMA) equipment. The results are shown in Table 2 below.
Referring to
Further, in the case of the comparative example 2-2 in which the thickness of the deposition layer is smaller than that of the example, physical properties decreased, compared to the example, because metal materials inside the polymer film layer have not been sufficiently formed.
Herein, in the case of the examples 2-3 and 2-4 which use indium (In), the processability has been improved due to a low melting point (160° C.) of indium, but physical properties of the current collector have decreased, compared to the case where aluminum or nickel having a melting point higher than that which has been set at the time of extrusion is used, which is because indium melted during extrusion may exist in a spherical form as well as a linear form while moving as shown in
The above description is merely illustrative of the technical idea of the present disclosure, and those skilled in the art to which the present disclosure pertains may make various modifications and variations without departing from the essential characteristics of the present disclosure. Therefore, the drawings disclosed in the present disclosure are not intended to limit the technical idea of the present disclosure but to describe the present disclosure, and the scope of the technical idea of the present disclosure is not limited by these drawings. The scope of protection of the present disclosure should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present disclosure.
On the other hand, in this specification, terms indicating directions such as up, down, left, right, before, and after are used, but it is obvious that these terms are for convenience of description only and may change depending on the location of the object or the location of the observer.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2021-0059193 | May 2021 | KR | national |
This application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/KR2021/016902, filed on Nov. 17, 2021, which claims priority from Korean Patent Application No. 10-2021-0059193, filed on May 7, 2021, and the contents which are incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2021/016902 | 11/17/2021 | WO |
