Electrode composite film, manufacturing method therefor, and lithium secondary battery comprising same

Abstract

The present invention relates to an electrode composite film comprising: a binder having a three-dimensional fiber network structure; and an electrode active material accommodated within the fiber network structure, wherein the electrode composite film has an R value, defined by the density and tensile strength of the electrode composite film, in the range of 5.0 to 10.0. By enhancing the sheet formation completeness of the electrode composite film, the R value can meet the range, thereby providing an electrode composite film with excellent mechanical strength, superior surface appearance, and stable performance in the lamination process with the current collector.

Description

Electrode composite film, method for producing the same, and lithium secondary battery comprising the same The present specification relates to an electrode composite film, a method for producing the same, and a lithium secondary battery including the same. Secondary batteries are used in small products such as digital cameras, P-DVDs, MP3Ps, mobile phones, PDAs, portable game devices, power tools, and e-bikes, as well as in large products requiring high output such as electric vehicles and hybrid vehicles, as well as in power storage devices that store surplus generated power or renewable energy and as backup power storage devices. Typically, secondary batteries are manufactured by applying electrode active material slurry to a positive electrode collector and a negative electrode collector to form an electrode active material layer, then drying and rolling the electrodes to manufacture the positive and negative electrodes, and laminating them on both sides of a separator to form an electrode assembly of a predetermined shape, then housing the electrode assembly in a battery case, injecting electrolyte, and sealing the assembly. Meanwhile, during the drying process of the electrode active material slurry, the solvent contained in the slurry may evaporate, causing defects such as pinholes or cracks in the electrode active material layer formed on the current collector. In addition, during the drying process, the inside and outside of the electrode active material slurry are not uniformly dried, so there is a concern that the quality of the electrode may deteriorate due to the powder floating phenomenon caused by the difference in the solvent evaporation rate, that is, the powder in the area that dries first rises and forms a gap with the area that dries relatively later. To solve the above problem, drying devices capable of controlling the evaporation rate of the solvent so that the inside and outside of the electrode active material slurry can be uniformly dried are being considered, but these drying devices are very expensive and require considerable cost and time to operate, which is disadvantageous in terms of manufacturing process. On the other hand, the solvent included in the conventional electrode active material slurry is N-methyl-2-pyrrolidone (NMP), which has a high boiling point, so it requires high heat energy and a very long drying process to dry, which is very disadvantageous for mass production. In addition, N-methyl-2-pyrrolidone (NMP) is a toxic substance and is harmful to living organisms, so it is not environmentally friendly. Accordingly, research on dry electrodes that manufacture electrodes without using a solvent has been actively conducted recently. The dry electrode is generally manufactured by laminating a free-standing type electrode composite film manufactured in the form of a sheet, which includes an electrode active material, a binder, a conductive material, etc., onto a current collector. The electrode composite film includes a process of first mixing an electrode active material, a carbon material as a conductive material, and a fiberizable binder together using a blender, etc., and then fiberizing the binder by applying a shear force through a process such as jet milling or kneading, and then calendering the obtained mixture into a film form to manufacture a free-standing film. Meanwhile, in the above electrode composite film manufacturing process, electrode powder is fed into a calendaring roll and rolled to manufacture an electrode composite film. However, the roll-to-roll process using a rolling roll is difficult to control, and if the number of calendaring cycles or the roll gap, etc. are not properly controlled, there is a problem that the defect rate of the film increases. In addition, in the case of an electrode composite film manufactured in this way, there is a problem that it exhibits inferior appearance characteristics or resistance characteristics. Therefore, there is a demand for the development of a dry electrode that can maintain the mechanical strength of the electrode composite film during the calendering process by a rolling roll in a roll-to-roll process and has excellent characteristics of the final manufactured electrode. In this specification, in order to solve the above problems, the compression density of the electrode composite film and the tensile strength in the MD and TD directions are controlled to provide an electrode composite film having excellent mechanical properties and excellent appearance and resistance characteristics. In addition, in order to solve the above problems and to provide an electrode composite film having the above characteristics, the present specification provides a method for manufacturing an electrode composite film, which controls the roll gap reduction rate of a rolling roll when sheeting an electrode powder into an electrode composite film using a rolling roll in a roll-to-roll process, and controls the compression density increase rate of the film before and after sheeting. In addition, in order to solve the above problems, the present specification provides a dry electrode having excellent resistance characteristics and durability due to superior mechanical properties in a dry electrode using the electrode composite film, thereby providing a lithium secondary battery having improved output characteristics and life characteristics. [1] In one aspect, an electrode composite film is provided, which comprises a binder having a three-dimensional fiber network structure; and an electrode active material accommodated within the fiber network structure, and has an R value of 5.0 to 10.0 defined by the following formula 1. [Formula 1] R = [dx (TS M )] / [(TS T )] In the above equation 1, d is a unitless number in the case of the compression density of the electrode composite film in g / cc, and the TS M is the MD direction tensile strength of the silver electrode composite film, and TS T is the tensile strength of the electrode composite film in the TD direction. [2] In the above [1], R defined by the above formula 1 may be 6.5 to 9.5. [3] In the above [1] and / or [2], the electrode composite film has a tensile strength in the TD direction (TS T) MD direction tensile strength (TS) M ) of the ratio (TS) M / TS T ) can be between 1.5 and 3.5. [4] In at least one of the above [1] to [3], the electrode composite film has a TD direction tensile strength (TS T ) MD direction tensile strength (TS) M ) of the ratio (TS) M / TS T ) can be between 2.0 and 3.2. [5] In at least one of the above [1] to [4], the electrode composite film may have a compression density of 2.4 g / cc to 3.4 g / cc. [6] In at least one of the above [1] to [5], the electrode active material may include a lithium transition metal compound containing at least one selected from the group consisting of nickel (Ni), cobalt (Co), manganese (Mn), and iron (Fe). [7] In at least one of the above [1] to [6], the binder may include polytetrafluoroethylene (PTFE). [8] In another aspect, a method for manufacturing an electrode composite film is provided, comprising: a step (S1) of manufacturing a pre-sheeting film by powder-sheeting an electrode powder including an electrode active material and a fiberizable binder in a roll-to-roll process including two or more pairs of rolling rolls; and a step (S2) of sheeting the pre-sheeting film three or more times while reducing the roll gap of the rolling rolls according to the number of turns. [9] In the above [8], the S2 step may be sheeting so that the MD direction tensile strength of the electrode composite film is 0.65 MPa or more.

[0010] In the above [8] and / or [9], the S2 step may be controlled so that the compression density increase rate of the preliminary composite film by sheeting is 5.0% or less.

[0011] In at least one of the above [8] to

[0010] , the S2 step may be controlled so that the roll gap of the first sheeting is reduced by 60% to 80% compared to the roll gap of the powder sheeting of the S1 step.

[0012] In at least one of the above [8] to

[0011] , the S2 step is controlled so that the roll gap of the Nth shooting is reduced by 30% to 60% compared to the roll gap of the (N-1)th shooting, and N may be an integer of 2 to 5.

[0013] In another aspect, a lithium secondary battery is provided, which includes a dry electrode, wherein the dry electrode includes the electrode composite film described above.

[0014] In the above

[0013] , the dry electrode may be a dry anode. The electrode composite film described herein can have excellent mechanical properties and excellent appearance characteristics and resistance characteristics by controlling the roll gap reduction rate of the rolling rolls when sheeting electrode powder into an electrode composite film using rolling rolls in a roll-to-roll process and controlling the compression density increase rate of the film before and after sheeting, thereby controlling the compression density and the tensile strength in the MD direction and the TD direction of the electrode composite film. In addition, the lithium secondary battery described herein has excellent durability due to the excellent mechanical properties of the electrode composite film, and includes a dry electrode with excellent appearance characteristics and improved electrode resistance, so that output characteristics and life characteristics can be improved. The terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as having meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to explain his or her own invention in the best manner. In this specification, MD direction (Machine Direction) means the longitudinal direction of the electrode composite film, and TD direction (Transverse Direction) means the width direction of the electrode composite film. In this specification, "Volume cumulative average particle diameter D 50 "In the particle size distribution curve, it means the particle size corresponding to 50% of the volume accumulation amount. The above D 50 For example, it can be measured using the laser diffraction method. The laser diffraction method can generally measure particle diameters from the submicron range to several mm, and can obtain results with high reproducibility and high resolution. In this specification, the "composite composition" means a mixture including an electrode active material and a binder (optionally, also including a conductive material), which is physically mixed to form a uniform dispersion phase, and may be a powder mixture as a product of a mixing process (mixing process) according to this specification, and may be one in which substantially no solvent is involved. Here, substantially no solvent is involved means that no solvent is added or only a very small amount of solvent is added when mixing the composite composition. In this specification, the “mixed aggregate” refers to a product of the kneading process (kneading process) according to this specification in which the composite composition is converted into an aggregate in a dough state by binding or connecting powder mixtures to each other as the binder is fiberized by receiving a shear force, and may have a solid content of 100%. In this specification, “electrode powder” may mean a material in a powder state in which the mixed aggregate is pulverized to make the particle size smaller. In this specification, the "electrode composite film" may mean a film manufactured in the form of a free-standing single sheet using the electrode powder without the intervention of a solvent. The term "free-standing" in this specification means that it can maintain a single form without relying on other members and can be moved or handled by itself. As described below, the electrode composite film may be formed by compressing the electrode powder, and may have a shape in which, for example, a layered structure is formed by being integrated by compressing. In this specification, the term "preliminary composite film" means a film from after the electrode powder is formed into a sheet shape through a powder-sheeting process in which the electrode powder first passes through a rolling roll in a roll-to-roll process until it passes through the last rolling roll in the process. It may be a self-supporting sheet, but may be a sheet with weak holding power, and may be used interchangeably with a "powder-sheeting film." Here, the "powder-sheeting" means that the electrode powder is manufactured into a self-supporting sheet shape through calendering, and "sheeting" may mean a calendering process performed in the process in which the powder-sheeted preliminary composite film is manufactured into an electrode composite film. In this specification, the “three-dimensional fiber network structure” may mean a structure that can be formed by fiberization of a binder during the process of sheet-forming an electrode composite film from a composite composition including an electrode active material and a binder. Specifically, the three-dimensional fiber network structure may mean various structures in which fine fibers formed by fiberization of a binder form a skeleton and thereby function as a support that enables the electrode composite film to become a self-supporting film. At this time, the electrode active material and, optionally, a conductive material may be accommodated in the pores formed in the three-dimensional fiber network structure. Electrode composite film In one aspect, the electrode composite film comprises a binder having a three-dimensional fiber network structure; and an electrode active material accommodated within the fiber network structure, and is characterized in that the R value defined by the following Equation 1 is 5.0 to 10.0. [Formula 1] R = [dx (TS M )] / [(TS T )] In the above equation 1, d is a unitless number in the case of the compression density of the electrode composite film in g / cc, and the TS M is the MD direction tensile strength of the silver electrode composite film, and TS T is the tensile strength of the electrode composite film in the TD direction. Electrode composite films undergo various processes, starting from a mixing process for forming a composite composition, to a kneading process for kneading the composite composition to form a mixed aggregate, to a pulverizing process for the mixed aggregate in the form of an aggregate in which the composite composition is kneaded, and to a sheeting process for electrode powder obtained by pulverizing the mixed aggregate, and thereby, the mechanical properties, appearance characteristics, and performance characteristics of the electrode are affected by various factors. In particular, the process for sheeting the electrode powder is a roll-to-roll process using a rolling roll, which has a high degree of process difficulty and, because it is a process for manufacturing powder in the form of a sheet without a special solvent, there is a problem that there is a considerable deviation in performance in terms of the mechanical properties and appearance characteristics of the manufactured film. From the powder sheeting of the above roll-to-roll process to the subsequent sheeting process, the process is controlled so that the loading amount and density of the electrode reach the target level as the roll rolling progresses. In this process, in order for the continuous process to proceed, the mechanical properties of the preliminary composite film by the initial powder sheeting have a great influence. Accordingly, in this specification, in order to secure the mechanical strength of the electrode composite film, including not only the appearance characteristics confirmed with the naked eye but also all potential cracks, etc., by defining R using the MD tensile strength and TD tensile strength of the electrode composite film and the compression density, the R value is intended to be 5 to 10, thereby providing an electrode composite film having excellent mechanical strength and appearance characteristics. R value of Equation 1: Tensile strength ratio and compressive density According to one embodiment, the electrode composite film has an R value defined by the above formula 1 of 5 to 10. The R value is the tensile strength (TS) in the TD direction. T ) Tensile strength (TS) in MD direction M) and the compression density (d), which means that the tensile strength in the MD direction to the tensile strength in the TD direction satisfies an appropriate level, but the ratio of this tensile strength can be controlled in relation to the compression density of the electrode composite film. The electrode composite film is manufactured in the form of a self-supporting sheet by forming a three-dimensional fiber network structure through the fiberizable binder becoming fiberized through the aforementioned process. In the process of manufacturing in the form of a sheet, the orientation of the binder may play an important role. Depending on the orientation of the binder, the tensile strength according to the direction of the film may differ. In terms of the stability of the self-supporting film, it may be desirable for the tensile strength in the MD direction to be greater than the tensile strength in the TD direction. On the other hand, since the sheet is manufactured through a roll-to-roll process, it is difficult to control the tensile strength in the TD direction, and thus the tensile strength in the MD direction is secured by controlling the process conditions. However, in this process, damage to the film due to excessive rolling occurs. However, this tendency may change depending on the compression density of the film. That is, even if the tensile strength in the MD direction has an appropriate value compared to the tensile strength in the TD direction, if the compression density is low, the durability may be low due to the low density even if the orientation is excellent, and even if the compression density is excellent, if the tensile strength in the MD direction is too high compared to the tensile strength in the TD direction, cracks may occur or the preliminary composite film may be broken during the roll rolling process. Therefore, it is necessary to determine the strength stability or durability of the electrode composite film by establishing a relationship such as the one defining the R value. When the above R value is less than 5, the MD direction tensile strength is low and TS M / TS TWhen the ratio is 2 or less or the compression density is low, it may mean a failure in the control of a series of powder-sheeting and sheeting continuous processes by a roll-to-roll process, and even when the continuous process is controlled, additional roll rolling may be required due to the low compression density, which may increase the possibility of film breakage. The electrode composite film manufactured in this way may have poor appearance characteristics, and in particular, the phenomenon of tearing occurring at the widthwise ends of the electrode composite film is prominent, and accordingly, the difference between the maximum and minimum values ​​in the widthwise direction becomes very large, which may cause a problem in that the usability as an electrode is very low. In addition, when the R value exceeds 10, it can be said that there is a pinhole or a potential crack in the electrode composite film that is difficult to confirm with the naked eye. That is, the tensile strength in the MD direction may be too high compared to the tensile strength in the TD direction, or the compressive density may be considerably high. In this case, the pre-pressure during rolling is excessively high, so the possibility of damage due to shear force or damage due to external impact increases rapidly. This may eventually cause problems such as damage during lamination with a current collector or cell assembly, or cracks occurring in one direction during the charge / discharge process of the cell. Therefore, the R value needs to be controlled so as not to become too large. Therefore, the R value needs to be adjusted to be 5 to 10, and preferably, the R value may be 5.5 or more, 5.7 or more, 6.0 or more, 6.5 or more, or 6.8 or more, and also 9.8 or less, 9.6 or less, 9.5 or less, 9.4 or less, or 9.2 or less. In one aspect, the electrode composite film has a TD direction tensile strength (TS T ) MD direction tensile strength (TS) M ) of the ratio (TS) M / TS T) may be 1.5 to 3.5. The ratio of the tensile strength in the MD direction to the TD direction is a factor that basically determines the mechanical strength of the electrode. The tensile strength in the MD direction should be higher than the tensile strength in the TD direction. However, if the value becomes too high, the anisotropic characteristics of the electrode composite film may become too strong, and the defect occurrence rate in one direction may become high compared to the strength of the film itself. Therefore, the tensile strength in the MD direction to the TD direction preferably satisfies the above range, and preferably, the lower limit may be 1.7 or more, 1.9 or more, 2.0 or more, or 2.2 or more, and the upper limit may be 3.4 or less, 3.2 or less, or 3.0 or less. In one aspect, the electrode composite film may have a compression density of 2.4 g / cc to 3.4 g / cc, preferably 2.5 g / cc or more, 2.6 g / cc or more, or 2.7 g / cc or more, and further 3.2 g / cc or less, 3.1 g / cc or less, or 3.0 g / cc or less. The compression density corresponds to an essential property that must be achieved during electrode manufacture depending on the case, and the value to be achieved may differ depending on the target, but it needs to be carefully considered in satisfying the defined R value together with the tensile strength ratio in the MD direction to the TD direction mentioned above. That is, even if the target compression density value is achieved, if the R value is not satisfied due to the tensile strength ratio, it can be expected that there will be a problem with the mechanical strength or appearance characteristics of the electrode composite film. In addition, even if the target value is slightly lower, the mechanical strength or appearance characteristics can be supplemented through the tensile strength ratio. Therefore, it is desirable to consider it together with the tensile strength ratio rather than considering it alone. In one aspect, the electrode composite film comprises an electrode active material and a fiberizable binder, and may optionally further comprise a conductive material. Electrode active material In one aspect, there is no particular limitation on the electrode active material as long as it is a commonly used electrode active material, and for example, the electrode active material may be a positive electrode active material or a negative electrode active material. The above positive electrode active material may include a lithium transition metal compound containing at least one selected from the group consisting of nickel (Ni), cobalt (Co), manganese (Mn), and iron (Fe), which is a compound capable of reversible intercalation and deintercalation of lithium. Specifically, it may include a lithium metal oxide containing lithium and one or more metals such as cobalt, manganese, nickel or aluminum. More specifically, the lithium metal oxide is a lithium-manganese oxide (e.g., LiMnO 2 , LiMn 2 O 4 etc.), lithium-cobalt oxides (e.g., LiCoO 2 etc.), lithium-nickel oxides (e.g., LiNiO 2 etc.), lithium-nickel-manganese oxides (e.g., LiNi 1-Y Mn Y O 2 (Here, 0 <Y<1), LiMn 2-Z Ni Z O 4 (wherein, 0<Z<2) etc.), lithium-nickel-cobalt oxides (e.g., LiNi 1-Y1 Co Y1 O 2 (Here, 0 <Y1<1) 등), 리튬-망간-코발트계 산화물(예를 들면, LiCo 1-Y2 Mn Y2 O 2 (Here, 0 <Y2<1), LiMn 2-Z1 Co Z1 O 4 (wherein, 0<Z1<2) etc.), lithium-nickel-manganese-cobalt oxides (e.g., Li(Ni p Co q Mn r )O 2(Here, 0<p<1, 0<q<1, 0<r<1, p+q+r=1) or Li(Ni p1 Co q1 Mn r1 )O 4 (wherein, 0<p1<2, 0<q1<2, 0<r1<2, p1+q1+r1=2) etc.), or lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r2 M s2 )O 2 (Here, M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r2, and s2 are atomic fractions of independent elements, respectively, such that 0<p2<1, 0<q2<1, 0<r2<1, 0<s2<1, p2+q2+r2+s2=1), etc.), and one or more compounds of these may be included. In addition, the positive electrode active material may include a lithium metal phosphate compound containing iron, and specifically may be lithium iron phosphate, and may be represented by, for example, the following chemical formula 1. [Chemical Formula 1] Li 1+a Fe 1-x M x PO 4 In the chemical formula 1 above, M is at least one selected from Mn, Co, Ni, Al, Mg, and Ti, and -0.5≤a≤0.5, 0≤x<1. When the above-mentioned positive electrode active material is a lithium metal phosphate-based compound, particularly when it is lithium iron phosphate, the positive electrode active material has a disadvantage in that its safety is guaranteed but its capacity is relatively small compared to lithium nickel-based oxide. However, according to one embodiment of the present invention, since a dry electrode capable of high loading can be implemented, it is possible to apply lithium iron phosphate with improved safety and improved capacity, and to implement a lithium secondary battery with excellent unit price competitiveness. Among these, the lithium metal oxide is LiCoO in that it can improve the capacity characteristics and stability of the battery. 2 , LiMnO 2 , LiNiO 2 , lithium nickel manganese cobalt oxide (e.g. Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O 2 , Li(Ni 0.6 Mn 0.2 Co 0.2 )O 2 , Li(Ni) 0.5 Mn 0.3 Co 0.2 )O 2 , Li(Ni 0.7 Mn 0.15 Co 0.15 )O 2 and Li(Ni 0.8 Mn 0.1 Co 0.1 )O 2 etc.), lithium nickel cobalt aluminum oxide (e.g., Li(Ni 0.8 Co 0.15 Al 0.05 )O 2 etc.), or lithium nickel manganese cobalt aluminum oxide (e.g. Li(Ni 0.86 Co 0.05 Mn 0.07 Al 0.02 )O 2 ), lithium iron phosphate (e.g. LiFePO 4 ) may be used, and one or a mixture of two or more of these may be used, or one doped with one or more transition metals may be applied. The above negative electrode active material may include at least one selected from the group consisting of lithium metal, a carbon material capable of reversibly intercalating / deintercalating lithium ions, a metal or an alloy of these metals and lithium, a metal composite oxide, a material capable of doping and dedoping lithium, and a transition metal oxide. As the carbon material capable of reversibly intercalating / deintercalating the lithium ion, any carbon-based negative electrode active material generally used in lithium ion secondary batteries can be used without particular limitation, and representative examples thereof include crystalline carbon, amorphous carbon, or a combination of these. Examples of the crystalline carbon include graphite such as amorphous, plate-shaped, flake-shaped, spherical, or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbide, calcined coke, and the like. As the above metal or an alloy of these metals with lithium, a metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn or an alloy of these metals with lithium can be used. The above metal composite oxides include PbO, PbO 2 , Pb 2 O 3 , Pb 3 O 4 , Sb 2 O 3 , Sb 2 O 4 , Sb 2 O 5 , GeO, GeO 2 , Bi 2 O 3 , Bi 2 O 4 , Bi 2 O 5 , Li x Fe 2 O 3 (0≤x≤1), Li x WO 2 (0≤x≤1) and Sn x Me 1-x Me' y O z(Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 로 이루어진 군에서 선택되는 것이 사용될 수 있다. Materials capable of doping and dedoping the above lithium include Si, SiO. x (0 <x≤2), Si-Y 합금(상기 Y는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Si은 아님), Sn, SnO 2 , Sn-Y (wherein Y is an element selected from the group consisting of alkali metals, alkaline earth metals, group 13 elements, group 14 elements, transition metals, rare earth elements and combinations thereof, but not Sn), and also at least one of these and SiO 2 can also be used in combination. The element Y may be selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof. Examples of the above transition metal oxides include lithium-containing titanium composite oxide (LTO), vanadium oxide, and lithium vanadium oxide. Meanwhile, according to one embodiment of the present invention, the electrode active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of the electrode composite film, preferably 85 wt% or more, 88 wt% or more, 90 wt% or more, 92 wt% or more, 93 wt% or more, or 95 wt% or more, and further 98.5 wt% or less, 98 wt% or less, or 97.5 wt% or less. When included in the above range, it may be preferable in terms of both the aspect of increasing the capacity and energy density of the electrode, and the aspect of optimizing the functions of the conductive material and the binder, which are auxiliary materials. Challenge In one aspect, the electrode composite film may optionally include a conductive material, and the conductive material is a component for further improving the conductivity of the electrode active material. The conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery. For example, the conductive material may be selected from the group consisting of carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; fluorinated carbon powder; graphite materials such as natural graphite or artificial graphite having crystallinity; fibrous carbon materials such as carbon fibers, carbon nanotubes, or carbon nanofibers; metal fibers; metal powders such as aluminum powder and nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives. Specifically, the conductive material may include at least one selected from the group consisting of graphite materials, carbon black, and carbon nanotubes (CNTs) for uniform mixing of the conductive material and improvement of conductivity. The conductive agent may be included in an amount of 0.1 wt% to 10.0 wt% based on the total weight of the electrode composite film. Preferably, it may be included in an amount of 0.2 wt% or more, 0.3 wt% or more, 0.5 wt% or more, or 0.7 wt% or more, and further may be included in an amount of 8.0 wt% or less, 6.0 wt% or less, or 5.0 wt% or less. The conductive agent may be advantageous for forming a conductive path as the amount introduced is larger, but the capacity may be lowered due to a relative decrease in the amount of active material, and it is not easy to control the amount introduced due to dispersion issues. However, the effect of forming a conductive path can be maximized by optimizing the dispersibility within the above range, so it may be desirable to apply the conductive agent within the above-mentioned range. bookbinder In one aspect, the binder has a function of forming a three-dimensional fiber network structure so that the electrode composite film can be self-supporting. The binder is not specifically specified as being fiberizable, that is, as long as it can form a three-dimensional fiber network structure in the electrode composite film through fiberization and provide pores capable of accommodating an electrode active material and optionally a conductive material. The fiberization of the above binder means a treatment to finely divide the high molecular polymer applied as the binder, and can be performed, for example, by applying a mechanical shear force, etc., and as a result, the surface is released and fiberized, thereby forming a plurality of fine fibers, and through this, a three-dimensional fiber network structure can be included. Such a fiberizable binder may preferably include at least one selected from the group consisting of polytetrafluoroethylene (PTFE), and polyolefin, and more preferably, a halogenated polyethylene including polytetrafluoroethylene may be applied, and for example, polytetrafluoroethylene, polychlorotrifluoroethlyene, polydichlorodifluoroethylene, or polytrichlorofluoroethylene, or polytetrachloroehtylene, and more preferably, polytetrafluoroethylene (PTFE). Specifically, the polytetrafluoroethylene (PTFE) may be included in an amount of 60 wt% or more based on the total binder weight. At this time, the binder may additionally include at least one of polyethylene oxide (PEO), polyvinylidene fluoride (PVdF), polyvinylidene fluoride-cohexafluoropropylene (PVdF-HFP), and a polyolefin-based binder. The above binder may be included in an amount of 0.1 wt% to 10.0 wt% based on the total weight of the electrode composite film, and preferably, 0.2 wt% or more, 0.3 wt% or more, 0.5 wt% or more, 0.7 wt% or more, or 1.0 wt% or more, and further, 9.0 wt% or less, 8.0 wt% or less, 7.0 wt% or less, or 5.0 wt% or less. In the case of a fiberizable binder, if it is included in the above range, there may not occur a problem of acting as resistance or a problem with the degree of fiberization for manufacturing in the form of a self-supporting sheet. The above electrode composite film may have a porosity of 17 vol% to 30 vol%, preferably 19 vol% or more, or 20 vol% or more, and may also have a porosity of 29 vol% or less, 28 vol% or less, 27 vol% or less, or 26 vol% or less. When the above range is satisfied, the electrolyte impregnation may be excellent, so that the life characteristics and output characteristics may be improved, and the energy density may be excellent. The porosity can be calculated using the following mathematical formula A. [Mathematical Formula A] Porosity (vol%) = {1-(electrode density / true density)} × 100 In the above mathematical expression A, the true density is the density of the electrode composite film measured when the electrode composite film is cut into a certain size and pressed with a press device until the thickness of the film does not change, and the electrode density is the density of the electrode composite film measured when the film is cut into a certain size. Method for manufacturing electrode composite film The method for manufacturing an electrode composite film according to the present invention is characterized by including a step (S1) of manufacturing a pre-composite film by powder-sheeting an electrode powder including an electrode active material and a binder, or an electrode powder optionally further including a conductive material, in a roll-to-roll process including two or more pairs of rolling rolls; and a step (S2) of sheeting the pre-composite film three or more times while reducing the roll gap of the rolling rolls according to the number of turns. The roll-to-roll process applied to the above S1 and S2 steps is a process including two or more pairs of rolling rolls, wherein the S1 step may be called a powder sheeting process, and the S2 step may be called a calendaring process, and may be a process in which a method of thermally compressing a supplied material using a plurality of rolling roll(s) is applied. The above-described calendar device may include a roll press section, and the roll press section may have rolling rolls arranged in pairs facing each other, and a plurality of such rolling roll pairs may be arranged continuously in the roll press section. When the rolling rolls are arranged in a plurality of consecutively, the temperature and main speed ratio (rotational speed ratio of one pair of rolls) of each roll may be the same or may satisfy the temperature of the calendering roll described above, and at this time, the rotational speed ratios of the rolling rolls may be appropriately controlled within a range of 1:1 to 1:10, respectively, independently. S1 stage Since the description of the electrode active material, conductive material and fiberizable binder is the same as that described above, a detailed description is omitted, and an electrode powder including the electrode active material, conductive material and fiberizable binder can be prepared as follows. 1) Preparation of powder for electrode In the process of obtaining the electrode powder according to one embodiment of the present invention, first, an electrode active material and a binder are mixed, and a conductive material is optionally mixed to obtain a composite composition. At this time, the mixing is performed so that the electrode active material, optionally a conductive material, and the binder can be uniformly distributed, and since they are mixed in a powder form, they can be mixed by various methods without limitation as long as they enable simple mixing thereof. However, in the manufacturing method according to one embodiment of the present invention, a dry method that does not use a solvent is applied, and therefore the mixing can be performed by dry mixing, and the materials can be mixed by putting them into a device such as a mixer or blender. The above mixing can be performed at 3,000 rpm to 20,000 rpm in a mixer, and preferably at 5,000 rpm to 15,000 rpm. When performed in the above range, the materials can be uniformly mixed, thereby improving battery performance. For example, the mixing speed can be 5,500 rpm or more, 6,000 rpm or more, or 6,500 rpm or more, and further 14,000 rpm or less, 13,000 rpm or less, or 12,000 rpm or less can be applied. The mixing can be performed at the same mixing speed as described above in the mixer, and can be mixed for 0.5 minutes to 60 minutes, and preferably 1 minute to 30 minutes, 1 minute to 20 minutes, or 1 minute to 10 minutes. Next, a fiberization process can be performed on the composite composition obtained from the above mixture to fiberize the binder. The above fiberization process is not particularly limited as long as it is generally performed, but preferably, it can be performed by high temperature and low shear kneading, and can be performed by a kneader, for example. By this kneading, the fiberizable binder is fiberized, thereby combining or linking the electrode active material and conductive powders, so that a mixed aggregate having a solid content of 100% can be formed. The above mixing can be performed at a speed of 10 rpm to 100 rpm, preferably 20 rpm or more, 30 rpm or more, 40 rpm or more, or 45 rpm or more, and can be performed at a speed of 80 rpm or less, 70 rpm or less, or 60 rpm or less. In addition, the mixing can be performed for 3 minutes to 60 minutes, preferably 4 minutes or more, or 5 minutes or more, and further, can be performed for 40 minutes or less, 30 minutes or less, 25 minutes or less, or 20 minutes or less. When the above range is satisfied, appropriate fiberization can proceed to improve the characteristics of the battery. In addition, the above mixing can be performed under conditions of high temperature and pressure higher than atmospheric pressure, and more specifically, can be performed under conditions of pressure higher than atmospheric pressure. More specifically, the mixing can be performed at a temperature of 50°C to 230°C, preferably 90°C to 200°C, more preferably 100°C or higher, 110°C or higher, or 120°C or higher, and furthermore 180°C or lower, 170°C or lower, or 160°C or lower. When the mixing is performed at a high temperature such as the above range, the fiberization and lumping of the binder due to the mixing can be well achieved, and the problem of breakage of the fiberized binder can be appropriately prevented. In addition, it can be performed at a pressure higher than atmospheric pressure, specifically at a pressure of 1 to 3 atm, more specifically at 1.1 to 3 atm. When performed within the above range, the problem of breakage of the binder in which fiberization has progressed can be appropriately prevented, and the problem of the density of the aggregate becoming too high can be prevented. That is, according to the present invention, when a high-temperature-low-shear mixing process is performed under conditions of high temperature and pressure higher than normal pressure instead of high-shear mixing, the effect intended by the present invention can be achieved. Next, a step of pulverizing the mixed aggregate manufactured through the above mixing step to obtain powder for electrodes can be performed. The mixed aggregates manufactured through the above mixing can be directly calendered (sheeted), but in this case, the mixed aggregates must be pressed under strong pressure and high temperature to manufacture them in the form of thin films, and thus, problems may arise in which the density of the film becomes too high or a uniform film cannot be obtained. Therefore, the mixed aggregates manufactured as described above are pulverized to manufacture powder for electrodes. The device used for the above grinding is not particularly limited, but it can preferably be performed by a device such as a blender or grinder. The above grinding can be performed at a speed of 1000 rpm to 15000 rpm for 5 seconds to 30 minutes, preferably at a speed of 3000 rpm to 8000 rpm for 30 seconds to 15 minutes. When performed within the above range, sufficient grinding can be achieved so that powder having a size appropriate for sheeting can be manufactured, and a large amount of fine powder may not be generated in the agglomerates. The average particle size of the above electrode powder may be 10 ㎛ to 3000 ㎛, specifically 50 ㎛ to 1500 ㎛, and more specifically 100 ㎛ to 700 ㎛. When the above range is satisfied, an electrode composite film having a uniform thickness and density can be formed, and excellent electrode composite film properties can be secured. Meanwhile, the electrode powder according to the present invention may additionally include fillers, although not essential, to suppress expansion of the electrode. The filler is not particularly limited as long as it is a fibrous material that does not cause a chemical change in the battery, and examples thereof include at least one selected from olefin polymers such as polyethylene and polypropylene; and fibrous materials such as glass fiber and carbon fiber. 2) Powder-sheeting of electrode powder The above step S1 is a process of manufacturing a preliminary composite film in the form of a self-supporting sheet by putting the electrode powder obtained as described above into a rolling roll of a roll-to-roll process including two or more pairs of rolling rolls. That is, as the very first step for manufacturing in the form of a self-supporting sheet, it can be manufactured in the form of a film through powder sheeting, but its strength or appearance may not be suitable for use as an electrode. However, even if an additional sheeting process is performed after powder sheeting, it is rare for the relative superiority of the state of the preliminary composite film after powder sheeting to change even after the final sheeting, and therefore it may be necessary to control this process as well. In the above powder-sheeting, the roll gap of the rolling rolls may be 250 ㎛ to 500 ㎛, preferably 280 ㎛ to 450 ㎛, and more preferably 280 ㎛ to 400 ㎛. The roll gap in the above range can minimize damage to the edge of the preliminary composite film and minimize cracks not only in the edge but also in the center, and it is preferable to perform the initial powder-sheeting within the above range. S2 stage The above S2 step is characterized in that the preliminary composite film that has undergone powder sheeting is sheeted three or more times, and the roll gap of the rolling roll during sheeting is gradually reduced while performing the sheeting three times. The above sheeting needs to be performed at least three times. The number of sheetings is ultimately intended to achieve a gradual increase in compression density, a gentle adjustment to the target film thickness, and an increase in the MD direction tensile strength, which may be difficult to achieve without reducing the roll gap. In the above sheeting, the compression density increase rate may be controlled to be 5.0% or less. That is, when the powder-sheeted pre-laminated film is sequentially sheeted, the change in the compression density before and after the sheeting should not be extreme, and it is desirable to control the roll gap so that the increase rate is 5.0% or less. This control of the compression density increase rate affects the mechanical strength and appearance characteristics of the electrode composite film, and can affect not only damage to the edge portion that can be visually confirmed, but also potential cracks that may occur during subsequent cell assembly or charge / discharge, and therefore it may be desirable to control it appropriately. Here, the compression density increase rate can be defined as the ratio of the amount of change in the compression density before and after sheeting to the compression density before sheeting. In the roll-to-roll process applied in the S1 and S2 steps while controlling the increase rate of the compression density, the roll gap reduction rate of the rolling rolls may be 30% to 80%. The roll gap reduction rate is preferably controlled in relation to the increase rate of the compression density, and in order to manufacture the electrode composite film so as to satisfy the R value described above, preferably, the first sheeting in the S2 step may be performed in a rolling roll having a roll gap reduced by about 60% to 80% compared to the roll gap on which the powder-sheeting in the S1 step was performed, that is, it may be preferable to control the roll gap reduction rate to be 60% to 80%. In addition, the S2 step may be controlled so that the roll gap of the Nth shooting after the first shooting is reduced by 30% to 60% compared to the roll gap of the (N-1)th shooting (previous shooting), and N may be an integer from 2 to 5. Here, the roll gap reduction rate may be defined as the ratio of the roll gap difference between the (N-1)th shooting and the Nth shooting to the roll gap of the Nth shooting. Although it may be important to apply all of these process control conditions, it may be of the utmost priority to ensure that the R value, defined as the ratio of the tensile strength in the MD direction to the tensile strength in the TD direction and the ratio of the compressive density, has a value between 5 and 10. The above three sheetings can adjust the roll gap to 100 ㎛ to 250 ㎛ during the first sheeting, and preferably 100 ㎛ to 200 ㎛, 100 ㎛ to 180 ㎛, or 100 ㎛ to 150 ㎛. In addition, the roll gap during the second sheeting can be 50 ㎛ to 100 ㎛, 60 ㎛ to 100 ㎛, or 70 ㎛ to 100 ㎛, and for the third sheeting, it can be adjusted to 10 ㎛ to 70 ㎛, 15 ㎛ to 70 ㎛, or 20 ㎛ to 70 ㎛. When the roll gap is controlled so as to satisfy the increase rate of the compression density and the decrease rate of the roll gap described above within the above range, an electrode composite film having excellent mechanical strength and appearance characteristics can be manufactured. The above shooting can be performed more than 3 times, and it is necessary to control that it does not exceed 10 times, and it must be performed at least 3 times, and if the above conditions are satisfied, the limitation may not be particularly problematic if it is performed more than 3 times. Dry electrode A dry electrode according to the present invention comprises an electrode composite film according to one embodiment of the present invention described above. Specifically, the dry electrode may comprise a current collector; and an electrode composite film of the present invention formed on the current collector. In addition, the dry electrode according to the present invention can be manufactured by laminating the electrode composite film on one side or both sides of a current collector and laminating the resultant product. The above lamination may be a step of rolling and attaching the electrode composite film onto a current collector. The above lamination may be performed by a roll press method using a lamination roller, and at this time, the lamination roller may be maintained at a temperature of 20°C to 200°C. When the above dry electrode is a positive electrode, the current collector may be any conductive material that does not cause a chemical change in the battery, and is not particularly limited. For example, the current collector may be stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. When the above dry electrode is a cathode, the current collector is not particularly limited as long as it has high conductivity without causing changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., an aluminum-cadmium alloy, etc. can be used. The thickness of the above-described collector may be 3 ㎛ to 500 ㎛, preferably 8 ㎛ or more, 10 ㎛ or more, or 20 ㎛ or more, and may also be 200 ㎛ or less, 100 ㎛ or less, or 80 ㎛ or less, but is not limited thereto. In addition, fine unevenness may be formed on the surface of the collector to increase the adhesive strength of the composite film. The above-mentioned collector may be used wholly or partially coated with a conductive primer to lower the resistance on the surface and improve the adhesion. Here, the conductive primer may include a conductive material and a binder, and the conductive material is not limited to a conductive material, but may be, for example, a carbon-based material. The binder may include a fluorine-based (including PVDF and PVDF copolymer), an acrylic-based binder, and an aqueous binder that can be dissolved in a solvent. Lithium secondary battery The lithium secondary battery according to the present invention comprises a dry electrode as described above, and the dry electrode comprises an electrode composite film as described above on a current collector. For example, the lithium secondary battery may include a secondary battery including a liquid electrolyte and an all-solid-state battery including a solid electrolyte. In the case where the lithium secondary battery according to one embodiment of the present invention is a secondary battery including a liquid electrolyte, a separator may be included between the plurality of electrodes. The separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries may be used without particular limitation, and in particular, one having low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fibers, polyethylene terephthalate fibers, etc. may also be used. Additionally, a coated separator containing ceramic components or polymer materials may be used to secure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure. In addition, when the lithium secondary battery is an all-solid-state battery, the solid electrolyte membrane can be manufactured so as to perform the function of the separator. In addition, examples of the electrolyte include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries. Specifically, the electrolyte may include an organic solvent and a lithium salt. The organic solvent may be used without particular limitation as long as it can act as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent may include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; Examples of solvents that can be used include carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; and sulfolanes. Among these, a carbonate solvent is preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) is more preferable. The above lithium salt can be used without any special limitation as long as it is a compound capable of providing lithium ions used in lithium secondary batteries. Specifically, the anion of the above lithium salt is F - , Cl - , Br - , I - , NO 3 - , N(CN) 2 - , BF 4 - , CF 3 CF 2 SO 3 - , (CF 3 SO 2 ) 2 N - , (FSO 2 ) 2 N - , CF 3 CF 2 (CF 3 ) 2 CO - , (CF 3 SO 2 ) 2 CH - , (SF 5 ) 3 C - , (CF 3 SO 2 ) 3 C - , CF 3 (CF 2 ) 7 SO 3 - , CF 3 CO 2 - , CH 3 CO 2 - , SCN - And (CF 3 CF 2 SO 2 ) 2 N - At least one selected from the group consisting of, and the lithium salt is LiPF 6 , LiClO 4, LiAsF 6 , LiBF 4 , LiSbF 6 , LiAl0 4 , LiAlCl 4 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiN(C 2 F 5 SO 3 ) 2 , LiN(C 2 F 5 SO 2 ) 2 , LiN(CF 3 SO 2 ) 2. LiCl, LiI, or LiB(C 2 O 4 ) 2 The concentration of the lithium salt is preferably used within the range of 0.1 M to 4.0 M, preferably 0.5 M to 3.0 M, and more preferably 1.0 M to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity, so that it can exhibit excellent electrolyte performance, and lithium ions can move effectively. In addition to the electrolyte components, the electrolyte may further contain one or more additives, such as, for example, haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxy ethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. In this case, the additives may be contained in an amount of 0.1 to 10.0 wt% with respect to the total weight of the electrolyte. In addition, since the lithium secondary battery according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, it is useful in portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs). Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided. The above battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, including power tools; electric vehicles including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); or power storage systems. Example Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. Examples 1 to 4 and Comparative Examples 1 to 6: Preparation of electrode composite films LiNi as a cathode active material 0.81 Co 0.05 Mn 0.12 Al 0.02 O 2 96 g of a composite material was mixed with 1.8 g of carbon black as a conductive agent and 2.2 g of polytetrafluoroethylene (PTFE) as a fiberizable binder to prepare a composite composition. The composite composition was then placed in a kneader and kneaded at a rotation speed of 50 rpm at 1.1 atm and 150°C for 5 minutes to prepare aggregates. The aggregates were then pulverized to prepare powder for an electrode. Thereafter, the electrode powder was pre-sheeted using a calendaring roll in a roll-to-roll process to manufacture a preliminary composite film, and the electrode composite film was manufactured by sheeting under the conditions shown in Table 1 below (roll diameter: 200 mm, roll speed ratio: 2:3.1). The MD direction tensile strength and compression density of the pre-composite film manufactured through powder sheeting in the above examples and comparative examples, and the MD direction tensile strength and compression density of the pre-composite film were measured and shown in Table 1 below. The tensile strength in the MD direction (MPa) was measured using a UTM device (ZwickRoell) according to the ASTM 638 method after cutting the film to 50 mm (MD) x 10 mm (TD), with a preload of 0.01 kg / cm and a speed of 50 mm / min. At this time, the maximum value (MPa) of the force applied until the sample did not break in the MD direction was obtained. The compression density (g / cc) was obtained as the ratio of the weight of the introduced composite composition to the volume of the films rolled by powder sheeting and each round of sheeting, and the density increase rate (%) was obtained using the following formula. Density Increase Rate (%) = [(Compression Density after Shooting) - (Compression Density before Shooting)] / (Compression Density before Shooting) Process Roll Gap (㎛) Roll Gap Reduction Rate (%) MD Tensile Strength (MPa) Compressive Density (g / cc) Density Increase Rate (%) MD Tensile Strength x Density Example 1 Powder-Sheeting 300-0.37 2.72-1.01 1st Sheeting 9070.00.45 2.82 3.68 1.27 2nd Sheeting 5044.40.68 2.93 3.90 1.99 3rd Sheeting 2060.00.82 3.07 4.78 2.52 Example 2 Powder-Sheeting 330-0.30 2.62-0.79 1st Sheeting 10069.70.39 2.69 2.67 1.05 2nd Sheeting 7030.00.42 2.78 3.35 1.173rd Sheeting Shooting3057.10.682.883.601.96Example 3 Powder-Shooting280-0.422.80-1.181st Shooting8071.40.552.903.571.602nd Shooting4050.00.893.003.452.673rd Shooting2050.01.103.113.673.42Example 4 Powder-Shooting280-0.402.78-1.111th Shooting10064.30.482.852.521.372nd Shooting4060.00.592.922.461.723rd Shooting2050.00.952.982.052.83Comparative Example 1 Powder-Shooting300-0.322.70-0.861st Shooting3090.00.352.793.330.98Comparative Example 2 Powder-Shooting330-0.252.52-0.631st Shooting10069.70.322.644.760.842nd Shooting2080.00.332.806.060.92Comparative Example 3 Powder-Shooting300-0.342.71-0.921st Shooting5083.30.382.855.171.082nd Shooting2060.00.413.025.961.24Comparative Example 4 Powder-Shooting330-0.112.50-0.281st Shooting15054.50.162.552.000.412th Shooting7053.30.202.601.960.52Comparative Example 5 Powder-Shooting330-0.332.60-0.861st Shooting10069.70.332.631.150.872th Shooting8020.00.342.640.380.903rd Shooting6025.00.352.650.380.93Comparative Example 6 Powder-Shooting300-0.302.63--1st Shooting22026.70.322.641.100.372th Shooting15031.80.342.662.130.833rd shooting 5066.70.392.714.742.42. Experimental Example 1: Measurement of physical properties of electrode composite films For the electrode composite films manufactured in the above examples and comparative examples, the tensile strength in the MD and TD directions was measured, the elongation was obtained, and the appearance characteristics were evaluated using the following methods. 1) Tensile strength (MPa) and elongation (%): After cutting the electrode composite film to 50 mm (MD) x 10 mm (TD), the tensile strength was measured using a UTM device (ZwickRoell) according to the ASTM 638 method, under the conditions of a preload of 0.01 kg / cm and a speed of 50 mm / min. At this time, the tensile strength (MPa) was obtained as the maximum value of the force applied until the sample did not break in each of the MD and TD directions, and the elongation (%) was obtained as the ratio of the specimen elongation until breakage occurred compared to the initial length (the ratio of the length just before breakage to the initial length as a percentage). 2) Compressed density (g / cc): It was calculated as the ratio of the weight of the introduced composite composition to the volume of the films rolled by powder sheeting and each round of sheeting. Tensile strength (MPa) Elongation (%) Compressive density (g / cc) RMDT DMD / TD Example 10.8 20.32 2.56 3.53 07 7.87 Example 20.68 0.25 2.72 3.92 88 7.83 Example 31.100 512 16 3.43 116 71 Example 40.95 0.313 06 3.22 989 13 Comparative Example 10.35 0.211 67 3.62 79 4.65 Comparative Example 20.33 0.27 1.22 3.42 803.42 Comparative Example 30.410.28 1.46 3.53 024.42 Comparative Example 40.200.054.002.02.6010.40Comparative Example 50.350.201.752.12.654.64Comparative Example 60.390.271.443.52.713.91 Referring to Table 2 above, in the case of Examples 1 to 4 where the reduction rate of the roll gap and the increase rate of the compression density were well controlled, it was possible to obtain an electrode composite film having excellent mechanical properties and satisfying the range of the R value, but in the case of Comparative Examples 1 to 4 where the sheeting process was not performed three or more times, the mechanical properties were poor, and accordingly, the R value was found to be less than 5 or more than 10. In addition, in the case of Comparative Examples 5 and 6 where the sheeting was performed three times but the reduction rate of the roll gap was not properly controlled, the mechanical properties were poor and accordingly, the R value was found to be less than 5. Experimental Example 2: Evaluation of Electrode Composite Film Regarding the appearance of the electrode composite films of the above examples and comparative examples, the degree of tearing at the edge portion was observed using the method below to evaluate the appearance, and the resistance of the electrode was measured. 1) Appearance evaluation (cm): The length of the part with the deepest tear and the shortest width in the width direction perpendicular to the length direction of the electrode composite film with a length of 30 cm was measured. 2) Electrode layer resistance (Ωcm): The electrode composite films manufactured in the examples and comparative examples were placed on aluminum foil (thickness: 15 ㎛) equipped with a conductive primer layer and laminated using a roll press maintained at 150°C to manufacture dry electrodes. After cutting each manufactured dry electrode to 100 mm x 100 mm, a current of 100 uA was applied to the electrode using the MP resistance measurement method, and the resistance value between the electrode composite film and the current collector layer was measured by the potential difference measured between 46 probes. Appearance Evaluation (cm) Electrode Resistance (Ωcm) Example 126.07.5 Example 225.48.5 Example 324.07.8 Example 425.08.2 Comparative Example 115.010.5 Comparative Example 219.010.2 Comparative Example 317.09.8 Comparative Example 420.011.5 Comparative Example 523.012.3 Comparative Example 618.010.8 Referring to Table 3 above, in the case of Examples 1 to 4, the degree of tearing at both ends of the film was alleviated, and the width of the normal product was measured to be considerably longer than that of the Comparative Examples, and the resistance of the electrode layer was also confirmed to be excellent. However, in the case of Comparative Examples 1 to 6, which did not satisfy the R value, the width of the normal product was considerably narrow in the appearance evaluation, and the quality was considerably poor, and the resistance was also confirmed to be very high. It can be presumed that this is due to the failure to properly control the process, so that the binder was not properly distributed during sheet forming, and the failure to control the tensile strength and density values ​​in the MD and TD directions.

Claims

1. A binder having a 3-dimensional fiber network structure; and an electrode active material contained within the fiber network structure, An electrode composite film having an R value of 5.0 to 10.0, as defined by the following equation 1: [Formula 1] R = [d x (TS M )] / [(TS T )] In the above equation 1, d is a unitless number in the case of the compression density of the electrode composite film in g / cc, and the TS M is the MD direction tensile strength of the silver electrode composite film, and TS T is the tensile strength of the electrode composite film in the TD direction.

2. In paragraph 1, An electrode composite film, wherein R, defined by the above formula 1, is 6.5 to 9.

5.

3. In paragraph 1, The above electrode composite film has a tensile strength in the TD direction (TS T ) MD direction tensile strength (TS) M ) of the ratio (TS) M / TS T ) is 1.5 to 3.5, electrode composite film.

4. In paragraph 1, The above electrode composite film has a tensile strength in the TD direction (TS T ) MD direction tensile strength (TS) M ) of the ratio (TS) M / TS T ) of 2.0 to 3.2, electrode composite film.

5. In paragraph 1, The above electrode composite film is an electrode composite film having a compression density of 2.4 g / cc to 3.4 g / cc.

6. In paragraph 1, An electrode composite film, wherein the electrode active material comprises a lithium transition metal compound containing at least one selected from the group consisting of nickel (Ni), cobalt (Co), manganese (Mn), and iron (Fe).

7. In paragraph 1, The above binder is an electrode composite film containing polytetrafluoroethylene (PTFE). In a roll-to-roll process involving 8.2 or more pairs of rolling rolls, Step (S1) of manufacturing a pre-composite film by powder-sheeting an electrode powder including an electrode active material and a binder; and A method for manufacturing an electrode composite film according to claim 1, comprising a step (S2) of sheeting the preliminary composite film three or more times while reducing the roll gap of the rolling roll according to the number of sheeting turns.

9. In paragraph 8, The above S2 step is a method for manufacturing an electrode composite film, wherein sheeting is performed so that the MD direction tensile strength of the electrode composite film is 0.65 MPa or more.

10. In paragraph 8, The above S2 step is a method for manufacturing an electrode composite film, wherein the pre-composite film is controlled so that the compression density increase rate by sheeting is 5.0% or less.

11. In paragraph 8, A method for manufacturing an electrode composite film, wherein the above step S2 is controlled so that the roll gap of the first sheeting is reduced by 60% to 80% compared to the roll gap of the powder sheeting of the step S1.

12. In paragraph 8, The above S2 step is controlled so that the roll gap of the Nth shooting is reduced by 30% to 60% compared to the roll gap of the (N-1)th shooting. A method for manufacturing an electrode composite film, wherein N is an integer from 2 to 5.

13. A lithium secondary battery comprising a dry electrode, wherein the dry electrode comprises an electrode composite film according to claim 1.

14. In paragraph 13, The above dry electrode is a dry positive electrode, a lithium secondary battery.