Conductive masterbatch and dry electrode manufactured using the same

Abstract

The present invention relates to a conductive material masterbatch for use in an electrode and an electrode manufactured using the conductive material masterbatch. An electrode manufactured using the conductive material masterbatch according to one aspect of the present invention may be characterized by having an electrode resistance of 55 Ω cm or less.

Description

[Technical Field]

[0001] The present invention relates to a conductive material masterbatch for use in dry electrodes, a method for producing the same, and electrodes produced using the same.

[0002] This application claims priority based on Korean Patent Application Nos. 2022-0049191 and 2022-0049192, filed on April 20, 2022, and the entire contents disclosed in the specifications and drawings of those applications are incorporated herein by reference. [Background technology]

[0003] The recent rapid increase in the use of fossil fuels has been remarkable, and as a result, the need for alternative and clean energy has grown rapidly. As part of this, the field in which research is being conducted most actively is the field of electrochemical power generation and storage.

[0004] At present, a typical example of an electrochemical element that uses such electrochemical energy is a secondary battery, and the range of its use is tending to expand more and more.

[0005] Lithium secondary batteries, which are typified by such secondary batteries, are not only used as energy sources for mobile devices, but have also recently reached a practical level of use as power sources for electric vehicles and hybrid electric vehicles that can replace vehicles that use fossil fuels such as gasoline vehicles and diesel vehicles, which are one of the main causes of air pollution, and their range of use is expanding to include auxiliary power sources through grid integration.

[0006] The manufacturing process of such a lithium secondary battery can be roughly divided into three steps: electrode process, assembly process, and chemical formation process. The electrode process can be further divided into an active material mixing process, an electrode coating process, a drying process, a rolling process, a slitting (cutting) process, and a winding process.

[0007] Among these, the active material mixing process is a process of blending coating materials to form an electrode active layer where the actual electrochemical reaction occurs in the electrode. Specifically, the electrode active material, which is an essential element of the electrode, and other additives such as conductive materials and fillers, binders for binding the powder particles together and adhering them to the current collector, and solvents for imparting viscosity and dispersing the powder, are mixed to produce a fluid slurry. The composition mixed to form the electrode active layer in this way is sometimes broadly referred to as an electrode mixture.

[0008] Thereafter, an electrode coating process is performed in which the electrode mixture is applied onto an electrically conductive current collector, and a drying process is performed to remove the solvent contained in the electrode mixture. The electrode is then rolled to a predetermined thickness.

[0009] However, evaporation of the solvent contained in the electrode mixture during the drying process can cause defects such as pinholes and cracks in the already formed electrode active layer. Furthermore, because the inside and outside of the active layer are not dried uniformly, differences in the evaporation rate of the solvent can lead to powder floating, i.e., powder in the first-dried area floats up, forming gaps with the later-dried area, potentially resulting in a deterioration in electrode quality. Therefore, active research efforts have recently been made to manufacture dry electrodes that do not use solvents.

[0010] Dry electrodes are generally manufactured by laminating a free-standing film containing an active material, a binder, a conductive material, etc., onto a current collector. To improve the workability of dry electrodes, a technology for manufacturing a powder mixture using processes such as mixing, kneading, and grinding raw materials for dry electrodes, such as activated carbon conductive material, active material, and binder, has been developed. However, this technology has encountered the problem that the larger the BET specific surface area of ​​the conductive material, the more difficult it is to uniformly disperse the conductive material, resulting in a higher content of conductive material compared to wet electrodes, making it difficult to efficiently use carbon nanotubes (CNTs) with their large BET specific surface area.

[0011] As a result, research and development efforts are currently being made not only to improve the dispersibility of conductive materials but also to improve the performance of dry electrodes manufactured using them. Summary of the Invention [Problem to be solved by the invention]

[0012] Therefore, an object of the present invention is to provide a conductive masterbatch that can be used to manufacture dry electrodes, and a method for manufacturing the same.

[0013] The present invention also aims to provide an electrode manufactured using, as a conductive material, a conductive material masterbatch in which the dispersibility of the conductive material is improved, and a method for manufacturing the electrode.

[0014] According to one aspect of the present invention, there is provided a conductive material masterbatch having a large BET specific surface area and improved dispersibility of a conductive material, and a manufacturing method thereof. The present invention also provides a conductive material masterbatch in which a high content of a conductive material is stably contained, and a manufacturing method thereof.

[0015] In another aspect, the present invention provides an electrode in which the electrode resistance characteristics are improved by using a conductive material masterbatch having a large BET specific surface area and improved dispersibility of the conductive material, thereby reducing the conductive material content, and a method for manufacturing the same.The present invention also provides an electrode in which the electrode resistance characteristics are improved while maintaining good mechanical properties such as tensile strength, and a method for manufacturing the same.

[0016] According to yet another aspect of the present invention, there is provided a method for manufacturing an electrode, which minimizes pulverization of an active material and maximizes fibrous binder, thereby improving flexibility and mechanical properties. [Means for solving the problem]

[0017] In order to solve the above problems, according to one aspect of the present invention, there is provided a conductive material masterbatch having the following features.

[0018] According to a first aspect, a conductive material is provided, comprising a polyvinylidene fluoride (PVDF) binder and a polytetrafluoroethylene (PTFE) binder, and the conductive material is 80 m 2 / g or more, and the crystallinity of the PVDF binder and the PTFE binder is independently 30% or less.

[0019] According to a second aspect, the conductive material may be the conductive material masterbatch according to the first aspect, which contains carbon nanotubes alone, or the conductive material may contain carbon nanotubes and point-like (dot-like) conductive material.

[0020] According to a third aspect, the dot-like conductive material may be the conductive material masterbatch according to the second aspect, which is carbon black, activated carbon, graphite, or a mixture of two or more of these.

[0021] According to a fourth aspect, the conductive material masterbatch may be the conductive material masterbatch according to any one of the second to third aspects, in which the weight ratio of the carbon nanotubes to the dot-like conductive material is 100:0 to 10:90.

[0022] According to a fifth aspect, the conductive material masterbatch may be the conductive material masterbatch according to any one of the second to fourth aspects, in which the carbon nanotubes are dispersed in the form of nanofibers.

[0023] According to a sixth aspect, the conductive material masterbatch may be the conductive material masterbatch according to any one of the second to fifth aspects, in which the carbon nanotubes have a diameter of 0.1 to 50 nm.

[0024] According to a seventh aspect, the conductive material masterbatch may be the conductive material masterbatch according to any one of the first to sixth aspects, wherein the PVDF-based binder includes PVDF, polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), or a mixture thereof.

[0025] According to an eighth aspect, the conductive material masterbatch may be the conductive material masterbatch according to any one of the first to seventh aspects, comprising 20 to 70 parts by weight of the conductive material, 5 to 60 parts by weight of the PVDF-based binder, and 0.1 to 50 parts by weight of the PTFE binder.

[0026] According to another aspect of the present invention, there is provided an electrode having the following configuration.

[0027] An electrode according to a ninth aspect includes a current collector and an electrode active material layer formed on at least one surface of the current collector. The electrode active material layer includes an electrode active material, an electrode conductive material, and an electrode binder. The electrode binder is fibrous to bind the electrode active material and the electrode conductive material together, and the electrode has an electrode resistance of 55 Ω cm or less.

[0028] According to a tenth aspect of the present invention, there may be provided an electrode according to the ninth aspect, wherein the content of the electrode conductive material is 1 wt % or less based on the total weight of the electrode active material layer.

[0029] According to an eleventh aspect of the present invention, there may be provided an electrode according to the ninth or tenth aspect, wherein the crystallinity of the electrode binder is 15% or less.

[0030] According to a twelfth aspect of the present invention, there may be provided an electrode according to any one of the ninth to eleventh aspects, wherein the content of the electrode active material is 95 wt % or more based on the total weight of the electrode active material layer.

[0031] According to a thirteenth aspect of the present invention, the electrode conductive material has a BET specific surface area of ​​80 m 2The electrode may be the electrode according to any one of the ninth to twelfth aspects, which comprises a carbon material having a conductivity of 1 / g or more.

[0032] According to a fourteenth aspect of the present invention, the electrode may be the electrode according to any one of the ninth to thirteenth aspects, in which the electrode conductive material comprises carbon nanotubes alone, or the conductive material comprises carbon nanotubes and point-like conductive materials.

[0033] According to a 15th aspect of the present invention, the electrode may be the electrode according to any one of the 9th to 14th aspects, wherein the electrode conductive material includes carbon nanotubes and dot-like conductive materials, and the dot-like conductive materials are carbon black, activated carbon, graphite, or a mixture of two or more of these.

[0034] According to a 16th aspect of the present invention, the electrode may be the electrode according to any one of the 9th to 15th aspects, in which the weight ratio of the carbon nanotubes to the dot-like conductive material is 100:0 to 10:90.

[0035] According to a seventeenth aspect of the present invention, the electrode may be the electrode according to any one of the ninth to sixteenth aspects, wherein the electrode conductive material and the electrode binder are derived from the conductive material masterbatch according to any one of the first to eighth aspects.

[0036] According to still another aspect of the present invention, there is provided a method for producing a conductive material masterbatch having the following embodiment.

[0037] A method for producing a conductive material masterbatch according to an eighteenth aspect includes the steps of: mixing a conductive material, a PVDF-based binder, and a PTFE binder to obtain a mixture; kneading and extruding the mixture to obtain extrudates; and pulverizing the extrudates. The conductive material is 80 ml or less. 2 / g or more, and the crystallinity of the PVDF binder and the PTFE binder in the produced conductive material masterbatch is independently 30% or less.

[0038] According to a nineteenth aspect, the method for producing a conductive material masterbatch according to the eighteenth aspect may be such that the step of obtaining the mixture comprises mixing at 200 rpm to 1,700 rpm for 1 minute to 30 minutes.

[0039] According to a twentieth aspect, the step of obtaining the extrudate may be the method for producing the conductive material masterbatch according to the eighteenth or nineteenth aspect, in which the mixture is charged into a twin screw extruder, melt-kneaded at an extrusion temperature of 100°C to 300°C and a screw speed of 50 rpm to 600 rpm, and extruded through a die.

[0040] According to a 21st aspect, the method for producing a conductive material masterbatch according to any one of the 18th to 20th aspects may be such that the pulverization is carried out at 500 rpm to 20,000 rpm for 5 seconds to 10 minutes.

[0041] According to still another aspect of the present invention, there is provided a method for producing an electrode having the following features.

[0042] A method for manufacturing an electrode according to a twenty-second aspect includes the steps of mixing a conductive material and a first binder to obtain a mixture, kneading and extruding the mixture to obtain an extrudate, pulverizing the extrudate to obtain a conductive material masterbatch, and forming an electrode active material layer on at least one surface of a current collector from a mixture including an electrode active material, the conductive material masterbatch, and a second binder.

[0043] According to a 23rd aspect, the step of forming the electrode active material layer may be the method for producing an electrode according to the 22nd aspect, including the steps of: mixing an electrode active material, the conductive material masterbatch, and a second binder to obtain a mixture; kneading the obtained mixture at a high temperature and a low shear rate to obtain a mixture mass; pulverizing the mixture mass with high shear to obtain a mixed powder for an electrode; calendaring the mixed powder for an electrode to obtain a mixture film; and positioning the mixed film on at least one surface of a current collector and laminating the mixed film.

[0044] A 24th aspect may be the method for producing an electrode according to the 22nd or 23rd aspect, in which the crystallinity of the first binder is 30% or less.

[0045] According to a 25th aspect, the method for producing an electrode according to any one of the 22nd to 24th aspects may be such that the tensile strength of the composite film is 0.2 MPa or more.

[0046] According to a 26th aspect, the electrode to be produced may be the method for producing an electrode according to any one of the 22nd to 25th aspects, in which the electrode has an electrode resistance of 55 Ω·cm or less.

[0047] According to still another aspect of the present invention, there is provided an electrochemical device having the following aspect.

[0048] An electrochemical device according to a 27th aspect of the present invention includes a positive electrode, a negative electrode, and a separation layer interposed between the positive electrode and the negative electrode, and at least one of the positive electrode and the negative electrode may be an electrode according to any one of the 9th to 17th aspects. [Effects of the Invention]

[0049] According to one aspect of the present invention, it is possible to provide a conductive material masterbatch that uses a conductive material having a large BET specific surface area and that has excellent adhesive strength with an active material during the production of an electrode. In addition, the conductive material masterbatch according to one aspect of the present invention has the effect of significantly improving the dispersibility of the conductive material having a large BET specific surface area.

[0050] According to another aspect of the present invention, an electrode having reduced electrode resistance, particularly an electrode having reduced electrode resistance, can be provided. Specifically, the electrode according to one aspect of the present invention is a so-called dry electrode that does not use a solvent during its manufacture, and has a lower conductive material content than conventional dry electrodes, thereby providing a dry electrode having an increased electrode active material content.

[0051] According to another aspect of the present invention, there is provided a dry electrode having improved electrode resistance and improved electrode film strength, thereby providing excellent electrical performance and improved stability, and an electrochemical device using the same.

[0052] According to yet another aspect of the present invention, by introducing a pulverization step after a high-temperature, low-shear kneading step instead of a high-shear mixing step, it is possible to provide a dry electrode in which pulverization of the electrode active material can be minimized, fibrous binder formation can be maximized, and shear shear of the fibrous binder can be minimized.

[0053] Furthermore, since the process does not involve a high-shear jet mill process and involves kneading using a kneader and pulverization, there is no problem of clogging of flow paths due to agglomeration of the constituent components, and therefore a manufacturing method can be provided that is advantageous for mass production of electrodes.

[0054] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further understand the technical concepts of the present invention as well as the content of the invention, and therefore the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief explanation of the drawings]

[0055] [Figure 1] 1 shows photographs of Examples 1 to 3 and Comparative Examples 1 and 2 described in this specification. [Figure 2] 1 shows scanning electron microscope (SEM) images of Examples 1 to 3 and Comparative Examples 1 and 2 described in this specification. [Figure 3] 1 is a schematic diagram of a process for producing a composite film according to one embodiment of the present invention. [Figure 4] 1 is a schematic diagram of an electrode lamination process according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0056] The present invention will be described in detail below.

[0057] The present invention relates to a conductive masterbatch for use in a dry electrode manufactured by pressing a mixed powder for an electrode, an electrode manufactured using the same, and a method for manufacturing the conductive masterbatch and the electrode, respectively.

[0058] In the present invention, the dry electrode can be used as an electrode for an electrochemical device such as a lithium ion secondary battery, but the use of the present invention is not limited thereto.

[0059] In this specification, the term "BET specific surface area" refers to a specific surface area measured by the BET method, and the BET specific surface area is a value calculated from the amount of nitrogen gas adsorbed at liquid nitrogen temperature (77 K) using a TriStar II 3020 apparatus manufactured by Micromeritics.

[0060] As used herein, the term "melting point" refers to a value measured by a conventional method for measuring the melting point (Tm) of a polymer. For example, the melting point may be measured using a differential scanning calorimeter (DSC).

[0061] As used herein, the term "crystallinity" is a measure for predicting the degree of kneadability and fiberization of a polymer, and can be measured, for example, using a differential scanning calorimeter (DSC).

[0062] As used herein, "diameter (D 50 )" refers to the diameter at the 50% point of the particle volume cumulative distribution according to diameter, and the diameter may be measured using a laser diffraction method. Specifically, the substance to be measured is dispersed in a dispersion medium, and then the dispersion medium is taken into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500). When the particles pass through a laser beam, the difference in the diffraction pattern according to diameter is measured to calculate the diameter distribution. By calculating the diameter at the 50% point of the particle volume cumulative distribution according to diameter in the measuring device, D 50 The diameter can be measured.

[0063] As used herein, the term "CNT dispersibility" refers to the property of CNTs being dispersed in the form of nanofibers without being aggregated into bundles. For example, the CNT dispersibility may be evaluated by SEM shape analysis.

[0064] Conductive Masterbatch According to one aspect of the present invention, there is provided a conductive material masterbatch for applying a conductive material having a large BET specific surface area to a dry electrode.

[0065] According to one aspect of the present invention, there is provided a conductive material masterbatch comprising a conductive material, a PVDF-based binder, and a PTFE binder, wherein the conductive material is 80 ml. 2 / g or more, and the crystallinity of the PVDF-based binder and the PTFE binder is independently 30% or less.

[0066] In the present invention, the conductive material is 80 m 2The conductive material has a BET specific surface area of ​​80 m / g or more. 2 / g or more, the content of the conductive material can be reduced and the content of the active material can be increased to increase the capacity of the dry electrode, but the function of the conductive material is not limited to the above.

[0067] In one embodiment of the present invention, the conductive material has a BET specific surface area of ​​80 m 2 Any conductive material can be used without particular limitations as long as it has a conductivity of 0.1g / g or more, does not cause chemical changes in the battery, and is conductive. Examples of the conductive material include graphite, such as natural graphite or artificial graphite; carbon black, such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers, such as carbon fiber and metal fiber; metal powders, such as carbon fluoride, aluminum, and nickel powder; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; and conductive materials, such as polyphenylene derivatives. More specifically, to achieve uniform mixing of the conductive material and improve conductivity, the conductive material can be carbon nanotubes, activated carbon, graphite, carbon black, or a mixture thereof.

[0068] In one aspect of the present invention, the conductive material may contain carbon nanotubes alone.

[0069] In another embodiment of the present invention, the conductive material may include carbon nanotubes and dot-shaped conductive material. In one embodiment of the present invention, the dot-shaped conductive material may be carbon black, activated carbon, graphite, or a mixture of two or more of these.

[0070] In yet another embodiment of the present invention, the conductive material may contain carbon nanotubes and dot-like conductive material in a weight ratio of 100:0 to 10:90. Here, when the weight ratio of the carbon nanotubes to the dot-like conductive material is 100:0, it means that the conductive material contains only carbon nanotubes.

[0071] In still another embodiment of the present invention, the conductive material includes carbon nanotubes and dot-like conductive material, and the weight ratio of the carbon nanotubes to the dot-like conductive material may be 99:1 to 50:50.

[0072] In still another embodiment of the present invention, when the conductive material contains carbon nanotubes, the carbon nanotubes can be dispersed in the conductive material masterbatch in the form of nanofibers by a PVDF-based binder and a PTFE binder.

[0073] In one embodiment of the present invention, the BET specific surface area of ​​the conductive material is specifically 80 m 2 / g or more and 2,000m 2 More specifically, the BET specific surface area of ​​the conductive material may be, for example, 100 m 2 / g or more, 150m 2 / g or more, 160m 2 / g or more, 500m 2 / g or more, 1,000m 2 / g or more, 2,000m 2 / g or less, 1,500m 2 / g or less, 1400m 2 / g or less, 300m 2 / g or less, 250m 2 / g or less, 210m 2 In another embodiment of the present invention, the conductive material may have a BET specific surface area of ​​80 m 2 / g or more and 300m 2 / g or less and a BET specific surface area of ​​100m 2 / g or more and 2,000m 2 When the BET specific surface area of ​​the conductive material is within the above-mentioned range, an advantageous effect is exhibited in terms of dispersion stability of the conductive material in the conductive material masterbatch, but the present invention is not limited thereto.

[0074] In another aspect of the present invention, when the conductive material contains carbon nanotubes, the diameter of the carbon nanotubes may be, for example, 0.1 to 50 nm, 1 to 30 nm, 5 to 25 nm, 10 to 20 nm, or 10 to 15 nm. In this specification, the diameter of the carbon nanotubes refers to the value measured at the cross section of the carbon nanotube in a direction perpendicular to the longitudinal direction, and the diameter may be measured, for example, by observation with an electron microscope such as a scanning electron microscope (SEM). When the diameter of the carbon nanotubes is within the above range, advantageous effects are exhibited in terms of CNT dispersibility, but the present invention is not limited thereto.

[0075] A conductive material masterbatch according to one aspect of the present invention contains the conductive material, a PVDF-based binder, and a PTFE binder.

[0076] In one aspect of the present invention, the conductive material masterbatch contains a PVDF-based binder as a binder, which is advantageous in terms of improving the binding strength with the conductive material described above, thereby reducing the binder content in the conductive material masterbatch and increasing the conductive material content, but the functions of the PVDF-based binder are not limited thereto.

[0077] In one aspect of the present invention, the conductive masterbatch can be used in a dry electrode in which an electrode film is formed by a binder fiberization method, as described below. In this case, the conductive masterbatch contains a PTFE binder as a binder, which is advantageous in terms of forming an electrode film by a binder fiberization method, but the function of the PTFE binder is not limited thereto.

[0078] In one aspect of the present invention, the conductive material masterbatch contains a PVDF-based binder and a PTFE binder as binders, thereby exhibiting excellent binding strength with the conductive material and improving the dispersibility of the conductive material having a high specific surface area. Furthermore, when an electrode film is formed using the conductive material by a binder fiberization method, the electrode film is stably formed, thereby exhibiting advantageous effects in realizing an electrode having low electrode resistance, but the mechanism of the present invention is not limited to these.

[0079] In one embodiment of the present invention, the PVDF-based binder may include a PVDF-based binder having a melting point of 200° C. or less. By using a PVDF-based binder having a melting point of 200° C. or less as the PVDF-based binder, the dispersibility and dispersion stability of the conductive material in a molten state can be improved, thereby enabling the preparation of a masterbatch, but the functions of the PVDF-based binder are not limited to the above.

[0080] In one embodiment of the present invention, the PVDF-based binder can be any polymer having a melting point of 200°C or less and containing at least one PVDF (polyvinylidene fluoride) repeating unit. The PVDF-based binder can be, for example, PVDF, polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), or a mixture thereof.

[0081] In one embodiment of the present invention, the melting point of the PVDF-based binder may be specifically 100° C. or higher and 200° C. or lower, for example, 100° C. or higher, 120° C. or higher, 140° C. or higher, 150° C. or higher, 160° C. or higher, 200° C. or lower, 190° C. or lower, 185° C. or lower, or 180° C. Alternatively, the melting point may be 100° C. or higher, 110° C. or higher, 120° C. or higher, 200° C. or lower, 190° C. or lower, 180° C. or lower, 170° C. or lower, 160° C. or lower, 150° C. or lower, or 140° C. or lower.

[0082] In one embodiment of the present invention, the PTFE binder may include a PTFE binder having a melting point of 300° C. to 380° C. By using a PTFE binder having a melting point of 300° C. to 380° C., the dispersibility and dispersion stability of the conductive material in a molten state can be improved, and a masterbatch can be produced, but the function of the PTFE binder is not limited to this function.

[0083] In one embodiment of the present invention, the PTFE binder can be any polymer having a melting point of 300°C to 380°C and containing one or more PTFE (polytetrafluoroethylene) repeating units within the repeating units of the polymer.

[0084] In one embodiment of the present invention, the PTFE binder may include polytetrafluoroethylene (PTFE).

[0085] In one embodiment of the present invention, the melting point of the PTFE binder may be specifically 300°C or higher, 310°C or higher, 320°C or higher, 330°C or higher, 335°C or higher, 380°C or lower, 370°C or lower, 360°C or lower, or 355°C or lower.

[0086] In one embodiment of the present invention, the crystallinity of the PVDF-based binder and the PTFE binder contained in the conductive material masterbatch may each independently be 30% or less.

[0087] In this specification, the crystallinity of the binder may be a value measured using a differential scanning calorimeter (DSC). Specifically, 5 to 12 mg of a sample is placed in the DSC, and the melting point and heat of fusion (ΔHm) are measured while the temperature is raised at a rate of 10°C / min in a nitrogen atmosphere in a temperature range of 25 to 360°C. The crystallinity can be measured according to the following formula using the heat of crystalline fusion (ΔHm°) according to the type of binder as a reference. Crystallinity of binder (Xc) = ΔHm / ΔHm° × 100%

[0088] In one embodiment of the present invention, the heat of crystalline fusion (ΔHm°) of the binder can be measured by referring to the following values: the 100% crystalline heat of fusion (ΔHm°) of the PVDF binder is 105 J / g, the 100% crystalline heat of fusion (ΔHm°) of the PVDF-HFP binder is 80 J / g, and the 100% crystalline heat of fusion (ΔHm°) of the PTFE binder is 85.4 J / g; alternatively, the crystallinity of each binder can be measured by referring to known values ​​in other documents.

[0089] In another embodiment of the present invention, when the PVDF-based binder contains PVDF, the crystallinity of PVDF in the conductive material masterbatch may be, more specifically, 30% or less, 28% or less, 27% or less, 26.5% or less, 26% or less, 25% or less, or 0%.

[0090] In still another embodiment of the present invention, when the PVDF-based binder contains PVDF-HFP, the crystallinity of the PVDF-HFP in the conductive material masterbatch may be, more specifically, 30% or less, 20% or less, 15% or less, 10% or less, 8% or less, 6% or less, or 0%.

[0091] In other embodiments of the present invention, the crystallinity of the PTFE binder may more specifically be 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, 5% or less, or 0%.

[0092] In yet another embodiment of the present invention, the crystallinity of the PVDF-based binder may be 30% or less, and the crystallinity of the PTFE binder may be 30% or less.

[0093] In yet another embodiment of the present invention, the crystallinity of the PVDF-based binder may be 30% or less, and the crystallinity of the PTFE binder may be 20% or less.

[0094] In one embodiment of the present invention, when the crystallinity of the PVDF-based binder satisfies the above range, an advantageous effect is achieved in terms of improving the dispersibility and dispersion stability of a conductive material having a large specific surface area, particularly CNTs, but the present invention is not limited thereto.

[0095] In one aspect of the present invention, when the crystallinity of the PTFE binder satisfies the above range, an advantageous effect is exhibited in terms of improving the physical properties of an electrode manufactured using the conductive material masterbatch, but the present invention is not limited thereto.

[0096] In one aspect of the present invention, the conductive material masterbatch contains 20 to 70 parts by weight of the conductive material, 5 to 60 parts by weight of a PVDF-based binder, and more than 0 but 50 or less parts by weight of a PTFE binder. Specifically, the conductive material masterbatch may contain 20 to 70 parts by weight of the conductive material, 5 to 60 parts by weight of a PVDF-based binder, and 0.1 to 50 or less parts by weight of a PTFE binder. For example, the conductive material masterbatch may contain 40 to 70 parts by weight of the conductive material, 40 to 50 parts by weight of a PVDF-based binder, and 5 to 30 parts by weight of a PTFE binder. More specifically, the conductive material masterbatch may contain 50 to 60 parts by weight of the conductive material, 30 to 40 parts by weight of a PVDF-based binder, and 10 to 20 parts by weight of a PTFE binder.

[0097] In one aspect of the present invention, when the content ratio of the conductive material, the PVDF-based binder, and the PTFE binder in the conductive material masterbatch satisfies the above range, when the conductive material masterbatch is mixed with an active material, the dispersibility of the conductive material is significantly improved, the ratio of the active material to the conductive material can be increased, and excellent adhesion strength between the conductive material and the active material can be achieved, but the present invention is not limited thereto.

[0098] In one embodiment of the present invention, the conductive material masterbatch may further contain a polyolefin binder in addition to the PVDF-based binder and the PTFE binder.

[0099] In another embodiment of the present invention, the conductive material masterbatch may further contain an active material in addition to the above-mentioned components, within the scope of the present invention.

[0100] electrode According to another aspect of the present invention, there is provided an electrode comprising a current collector and an electrode active material layer formed on at least one surface of the current collector, the electrode active material layer including an electrode active material, an electrode conductive material, and an electrode binder, the electrode binder being fibrous to bind the electrode active material and the electrode conductive material, and having an electrode resistance of 55 Ω cm or less.

[0101] An electrode according to another aspect of the present invention may be manufactured using the conductive material masterbatch described above.

[0102] In one aspect of the present invention, the electrode may include a fiberized electrode binder as a means for binding the electrode active material and the electrode conductive material. Such a fiberized electrode binder exhibits less breakage than conventional non-fiberized binders and has excellent longitudinal extensibility, thereby improving the flexibility of the electrode active material layer and the electrode itself including the same. The fiberization process of the electrode binder will be described in detail in the section on the electrode manufacturing method described below.

[0103] In one aspect of the present invention, the electrode active material layer may be derived from a free-standing electrode film. For example, the electrode may have a current collector and an electrode active material layer derived from an electrode film disposed on at least one surface of the current collector. The electrode film and the current collector may be bonded together by a lamination process or the like.

[0104] In one embodiment of the present invention, the electrode active material layer may be an electrode film, which may be manufactured in the form of a free-standing sheet using an electrode material including an electrode active material, an electrode conductive material, and an electrode binder without the use of a solvent. In this specification, the term "free-standing" means that the electrode film can maintain its shape independently of other components and can be moved or handled by itself.

[0105] The electrode active material layer may be formed by compressing a powder mixture for an electrode, as described below. For example, the electrode active material layer may have a layered structure formed by compressing and accumulating the powder mixture for an electrode. The powder mixture for an electrode refers to a powdered electrode material containing an electrode active material, an electrode conductive material, and an electrode binder. For example, the powder mixture for an electrode may be obtained by pulverizing a mixture mass containing the electrode active material, the electrode conductive material, and the electrode binder, as described below.

[0106] In the present invention, the electrode has a resistance of 55 Ω·cm or less.

[0107] In this specification, the resistance of the electrode is a value measured as follows: The electrode to be measured for resistance was placed in a 50×50 mm 2 The prepared electrode sample was placed in a multi-probe tester (RM2610, manufactured by Hioki E.E. Corporation), and the potential difference measured between each of the 45 probes was measured under conditions of a positive current of 100 μA, a negative current of 10 mA, and a voltage of 0.5 V, and this was expressed as the electrode resistance value.

[0108] Conventionally, the lack of solvents in the manufacture of dry electrodes has led to a problem of poor dispersibility of conductive materials. In particular, conductive materials with a large BET specific surface area are not suitable for use in the manufacture of dry electrodes because they are not stably dispersed. Therefore, attempts have been made to improve the electrical properties of electrodes by using conductive materials with a small BET specific surface area and increasing the content of the conductive material. However, increasing the content of the conductive material reduces the content of the active material, potentially reducing the capacity of the electrode. Furthermore, reducing the content of the binder reduces the current collecting ability with the current collector and the binding strength between the active material and the electrode, potentially increasing the electrode resistance.

[0109] According to one aspect of the present invention, the electrode active material layer has improved dispersibility of a conductive material having a large BET specific surface area, thereby significantly reducing electrode resistance despite containing a small amount of conductive material, thereby providing a dry electrode with improved electrical properties, although the mechanism of the present invention is not limited thereto.

[0110] In one embodiment of the present invention, the content of the electrode conductive material may be, for example, 1 wt % or less based on the total weight of the electrode active material layer, specifically, 0.1 wt % to 1 wt % or 0.1 wt % to 0.8 wt % based on the total weight of the electrode active material layer.

[0111] Thus, according to one aspect of the present invention, the content of the electrode active material in the electrode active material layer can be increased. In one aspect of the present invention, the content of the electrode active material can be 95 wt % or more, 96 wt % or more, 97 wt % to 99 wt %, 97 wt % to 98 wt %, or 97 wt % to 97.5 wt % based on the total weight of the electrode active material layer.

[0112] Thus, according to one aspect of the present invention, the electrode active material layer has an improved electrode resistance value despite a low content of the electrode conductive material. For example, the electrode may have an electrode resistance value of 55 Ω cm or less while containing 0.8 wt % or less of the conductive material based on the total weight of the electrode active material layer.

[0113] In particular, the electrode may have a resistance of 45 Ω·cm or less when the content of the conductive material contained in the electrode active material layer is converted to 1 wt % according to the following formula 1: [Formula 1] Rt = Cw × Rw …1

[0114] In the above formula 1, Rt represents the electrode resistance value converted based on 1 wt % of the conductive material, Cw represents the content of the conductive material based on the total weight of the electrode active material layer in the target electrode, and Rw represents the electrode resistance value of the target electrode.

[0115] As described above, according to another aspect of the present invention, the conductive material and binder contained in the electrode may be derived from the conductive material masterbatch described above.

[0116] That is, the "electrode conductive material" may be the "conductive material" described above in the section on the conductive material masterbatch. Accordingly, the explanation about the conductive material described in the section on the conductive material masterbatch is to be applied to the "electrode conductive material" of the electrode.

[0117] The "electrode binder" may include the "binder" described above in the section on the conductive material masterbatch. Accordingly, the description of the binder described in the section on the conductive material masterbatch is also applied to the "electrode binder" of the electrode.

[0118] For example, the electrode conductive material is 80 m 2 / g or more.

[0119] The electrode conductive material may be carbon nanotubes alone or may include carbon nanotubes and dot-like conductive materials, and the types of the dot-like conductive materials and the weight ratio of the carbon nanotubes and dot-like conductive materials are the same as those described above.

[0120] According to another aspect of the present invention, an electrode includes an electrode active material layer formed using the conductive material masterbatch, thereby improving the dispersibility of the conductive material having a large BET specific surface area, thereby enabling the conductive material having a large BET specific surface area to be stably contained in the electrode active material layer. As a result, the content of the conductive material in the electrode active material layer can be reduced and the content of the active material can be increased, thereby improving the resistance characteristics of the electrode.

[0121] The electrode binder may also contain a PVDF-based binder and a PTFE-based binder derived from the conductive material masterbatch.

[0122] In addition to these, the electrode binder is not limited to any particular one as long as it can be fibrillated in the manufacturing method described below, particularly in the process of manufacturing the mixture mass. The fibrillation refers to a process in which a high molecular weight polymer is finely divided, and can be performed using, for example, mechanical shear force. The surface of the polymer fiber fibrillated in this manner is loosened to produce a large number of microfibers (fibrils).

[0123] According to one aspect of the present invention, the electrode binder may include, but is not limited to, polytetrafluoroethylene (PTFE), polyolefin, or a mixture thereof. Specifically, the polytetrafluoroethylene (PTFE) may be included in an amount of 60 wt% or more based on the total weight of the entire binder polymer. It should be noted that the binder material may further include one or more of polyethylene oxide (PEO), polyvinylidene fluoride (PVdF), polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HMP), and a polyolefin-based polymer.

[0124] In one embodiment of the present invention, the binder polymer contained in the electrode active material layer may be one added for producing a mixed powder for an electrode, i.e., a second binder, or one added for producing a conductive material masterbatch, i.e., a first binder, as will be described later in the section on the electrode production method, or one added in both stages.

[0125] In one embodiment of the present invention, the crystallinity of the electrode binder may be, for example, 15% or less, specifically 10% or less.

[0126] In one embodiment of the present invention, the electrode binder may include a binder derived from the conductive material masterbatch. For example, the conductive material masterbatch may include a PVDF-based binder polymer and a PTFE binder polymer, each of which may independently have a crystallinity of 30% or less. That is, the crystallinity of the binder included in the conductive material masterbatch may be 30% or less, and when the binder is used to prepare a mixed powder for an electrode, the binder may be further fibrous during the kneading step, reducing its crystallinity to a level of 15% or less.

[0127] In one aspect of the present invention, when the crystallinity of the PTFE binder satisfies the above range, an advantageous effect is exhibited in terms of improving the physical properties of an electrode manufactured using the conductive material masterbatch, but the present invention is not limited thereto.

[0128] In one embodiment of the present invention, the content of the electrode binder may be, for example, 0.1 wt % to 5 wt %, 0.1 wt % to 4 wt %, 0.1 wt % to 3 wt %, or 0.1 to 2.5 wt % based on the total weight of the electrode active material layer, but the present invention is not limited thereto.

[0129] In one embodiment of the present invention, the electrode active material layer may contain a positive electrode active material or a negative electrode active material depending on the polarity of the battery.

[0130] Non-limiting examples of the positive electrode active material include, but are not limited to, lithium transition metal oxides, lithium metal iron phosphates, lithium nickel-manganese-cobalt oxides, and oxides in which a portion of the lithium nickel-manganese-cobalt oxide is substituted with another transition metal, or two or more of these. Specifically, the positive electrode active material may include, for example, layered compounds such as lithium cobalt oxide (LiCoO) and lithium nickel oxide (LiNiO), or compounds substituted with one or more transition metals; 1+x Mn 2-xO4 (where x is from 0 to 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3), Ni-site type lithium nickel oxides represented by this formula; chemical formula LiMn 2-x M x O2 (where M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or lithium manganese composite oxides represented by Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); lithium metal phosphate LiMPO4 (where M = Fe, CO, Ni, or Mn); lithium nickel-manganese-cobalt oxide Li 1+x (Ni a Co b Mn c ) 1-x O2 (x = 0 to 0.03, a = 0.3 to 0.95, b = 0.01 to 0.35, c = 0.01 to 0.5, a + b + c = 1); oxides in which part of lithium nickel-manganese-cobalt oxide is substituted with aluminum, Li a [Ni b Co c Mn d [[ID=二十]]Al e )[[ID=二十九]] 1-f M1 f O2 (M1 is one or more selected from the group consisting of Zr, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, F, P and S, 0.8 ≤ a ≤ 1.2, 0.5 ≤ b ≤ 0.99, 0 < c < 0.5, 0 < d < 0.5, 0.01 ≤ e ≤ <0.1, 0 ≤ f ≤ 0.1); oxides in which part of lithium nickel-manganese-cobalt oxide is substituted with other transition metals, Li 1+x (Ni a Co b Mn c M d ) 1-xO2 (x=0 to 0.03, a=0.3 to 0.95, b=0.01 to 0.35, c=0.01 to 0.5, d=0.001 to 0.03, a+b+c+d=1, M is any one selected from the group consisting of Fe, V, Cr, Ti, W, Ta, Mg, and Mo), disulfide compounds; Fe2(MoO4)3, and the like, but are not limited to these.

[0131] Non-limiting examples of the negative electrode active material include carbon such as non-graphitizable carbon and graphite-based carbon; x Fe2O3(0≦x≦1), Li x WO2(0≦x≦1), Sn x Me 1-x Me' y O z Metal composite oxides such as (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si), elements of Groups 1, 2, and 3 of the periodic table, and halogens; 0≦x≦1; 1≦y≦3; 1≦z≦8); lithium metal; lithium alloys; silicon-based alloys; tin-based alloys; silicon-based oxides such as SiO, SiO / C, and SiO2; 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.

[0132] In one aspect of the present invention, the current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and examples thereof include stainless steel, aluminum, nickel, titanium, baked carbon, copper, or aluminum or stainless steel whose surface has been surface-treated with carbon, nickel, titanium, silver, etc. The current collector can also be formed with minute irregularities on its surface to increase the adhesive strength of the positive electrode active material, and a wide variety of forms can be used, such as a film, sheet, foil, net, porous material, foam, or nonwoven fabric.

[0133] In one embodiment of the present invention, the current collector may be fully or partially coated with a conductive primer to reduce surface resistance and improve adhesion. The conductive primer may include a conductive material and a binder. The conductive material may be any conductive material, including, but not limited to, a carbon-based material. The binder may include solvent-soluble fluorine-based binders (including PVDF and PVDF copolymers), acrylic binders, and water-based binders.

[0134] Manufacturing method of conductive masterbatch According to yet another aspect of the present invention, there is provided a method for producing the above-mentioned conductive material masterbatch.

[0135] A method for producing a conductive masterbatch according to another aspect of the present invention includes the steps of: mixing a conductive material, a PVDF-based binder, and a PTFE binder to obtain a mixture; kneading and extruding the mixture to obtain extrudates; and pulverizing the extrudates, wherein the conductive material is 80 ml or less. 2 / g or more, and the crystallinity of the PVDF binder and the PTFE binder in the produced conductive material masterbatch is independently 30% or less.

[0136] In the method for producing a conductive material masterbatch of the present invention, the conductive material, PVDF-based binder, and PTFE binder are the same as those described in the section on the conductive material masterbatch.

[0137] In one aspect of the present invention, the mixing for obtaining the mixture of the conductive material, PVDF-based binder, and PTFE binder is performed so that the conductive material, PVDF-based binder, and PTFE binder are uniformly distributed. Since these components are mixed in powder form, they may be mixed by a variety of methods that allow simple mixing without any particular limitation. The conductive material masterbatch may be prepared by dry mixing, which may be performed by feeding the materials into a device such as a blender or super mixer.

[0138] In one embodiment of the present invention, the step of obtaining the mixture may involve mixing in a super mixer at 200 rpm to 1,700 rpm for 1 minute to 30 minutes, or more specifically, mixing in a mixer at 1,000 rpm to 1,500 rpm for 2 minutes to 7 minutes.

[0139] The method for producing the conductive masterbatch includes the steps of kneading and extruding the mixture to fiberize the binder in the mixture to obtain an extrudate from the mixture.

[0140] In one embodiment of the present invention, the step of obtaining the extrudate may be performed using, for example, a twin screw extruder. By obtaining the extrudate using a twin screw extruder, it is possible to achieve an effect that the crystallinity of each of the PVDF-based binder and the PTFE-based binder in the produced conductive material masterbatch can be set to 30% or less.

[0141] In one embodiment of the present invention, each screw in the twin-screw extruder may have a diameter (Φ) of, for example, 10 to 40, 15 to 35, or 20 to 30, specifically 25, and a length (L) / diameter (D) ratio (L / D) of 40 to 60, 45 to 55, for example, 48.

[0142] In one embodiment of the present invention, the step of obtaining the extrudate can be specifically performed by feeding the mixture into the twin-screw extruder, melt-kneading the mixture at an extrusion temperature of 100°C to 300°C and a screw speed of 50 rpm to 600 rpm, and extruding the mixture through a die.

[0143] In one embodiment of the present invention, the extrusion temperature may be, for example, 130° C. to 230° C. or 140° C. to 220° C. In one embodiment of the present invention, if the extrusion temperature is too low below the above range, fiberization of the binder and agglomeration of the mixture by kneading may not be performed well, and the extrudate may be compressed into a powder. If the extrusion temperature is too high above the above range, the crystallinity of the binder may decrease rapidly, and thermal decomposition may occur, which may be undesirable, but the present invention is not limited thereto.

[0144] In one embodiment of the present invention, the screw speed in the twin-screw extruder can be, for example, 150 rpm to 450 rpm, 300 rpm to 450 rpm, 350 rpm to 450 rpm, or 400 rpm.

[0145] In one embodiment of the present invention, the shape of the die during the extrusion may be rectangular or circular, but the present invention is not limited thereto.

[0146] In one aspect of the present invention, the pulverizing step is performed to cut the conductive masterbatch so that it can be easily mixed with the powdered active material during subsequent electrode production, and the extrudate is pulverized by a conventional method so that it has an appropriate size and shape, and the method is not particularly limited.

[0147] In one embodiment of the present invention, the extrudate is placed in a blender and crushed at 5,000 rpm to 20,000 rpm for 10 seconds to 10 minutes, or at 8,000 rpm to 15,000 rpm or 10,000 rpm for 20 seconds to 1 minute, or 30 seconds.

[0148] The conductive material masterbatch produced in the above manner has the characteristic that the conductive material is uniformly dispersed and the crystallinity of the added PVDF-based binder and PTFE binder can each be 30% or less.

[0149] The conductive material masterbatch produced as described above can be used to produce electrodes, particularly dry electrodes, but the use of the conductive material masterbatch is not limited to this in any way.

[0150] Electrode manufacturing method According to yet another aspect of the present invention, there is provided a method for manufacturing the above-described electrode.

[0151] A method for manufacturing an electrode according to yet another aspect of the present invention includes the steps of mixing a conductive material and a first binder to obtain a mixture, kneading and extruding the mixture to obtain an extrudate, pulverizing the extrudate to obtain a conductive material masterbatch, and forming an electrode active material layer on at least one surface of a current collector from the mixture containing an electrode active material, the conductive material masterbatch, and a second binder.

[0152] According to one aspect of the present invention, the conductive material may be the same as that described above in the section on the conductive material masterbatch.

[0153] According to one embodiment of the present invention, the first binder and the second binder may each use the items described above in the section on the electrode. For example, the first binder and the second binder may each independently be of a type commonly used in the manufacture of electrodes, and the types are not particularly limited.

[0154] According to one embodiment of the present invention, the first binder may be a binder used in the conductive material masterbatch, and specifically may include a PVDF-based binder, a PTFE-based binder, or a mixture thereof.

[0155] According to one embodiment of the present invention, the second binder may be a conventional binder used in the manufacture of electrodes, and may include, for example, a PVDF-based binder, a PTFE-based binder, a polyolefin binder, or a mixture of two or more of these.

[0156] According to another aspect of the present invention, a method for manufacturing an electrode may include forming an electrode active material layer using the conductive material masterbatch described above. That is, the method for manufacturing an electrode may be broadly divided into a process for manufacturing a conductive material masterbatch and a process for manufacturing an electrode using the manufactured conductive material masterbatch as a conductive material.

[0157] From this perspective, the first binder may be a binder used in a process for producing a conductive material masterbatch, and the second binder may be an electrode binder used in a process for producing an electrode using the conductive material masterbatch.

[0158] Furthermore, the step of obtaining a mixture, the kneading step, and the pulverization step included in the manufacturing process of the conductive material masterbatch may be referred to as a first mixing step, a first kneading step, and a first pulverization step, respectively. Furthermore, the step of obtaining a mixture, the kneading step, and the pulverization step included in the manufacturing process of an electrode using the conductive material masterbatch may be referred to as a second mixing step, a second kneading step, and a second pulverization step, respectively.

[0159] According to one aspect of the present invention, the method for producing an electrode includes the steps of obtaining the above-described conductive material masterbatch and forming an electrode active material layer.

[0160] In one embodiment of the present invention, the process for producing an electrode using the conductive material masterbatch includes forming an electrode active material layer on at least one surface of a current collector, the electrode active material layer including an electrode active material, the conductive material masterbatch, and a second binder polymer.

[0161] In one aspect of the present invention, the step of forming the electrode active material layer may include a process of preparing a mixed powder for an electrode from the electrode active material, the conductive material masterbatch, and a binder polymer (second binder), and then laminating a free-standing electrode film obtained from the mixed powder for an electrode onto at least one surface of a current collector.

[0162] According to yet another aspect of the present invention, there is provided a method for manufacturing an electrode, the method including: mixing a conductive material and a first binder to obtain a mixture (first mixing step); kneading and extruding the mixture to obtain an extrudate (first kneading step); pulverizing the extrudate to obtain a conductive material masterbatch (first pulverization step); mixing an electrode active material, the conductive material masterbatch, and a second binder to obtain a mixture (second mixing step); kneading the mixture obtained from the second mixing step at a high temperature and a low shear rate to obtain a mixture mass (second kneading step); pulverizing the mixture mass at high shear to obtain a mixed powder for an electrode (second pulverization step); calendering the mixed powder for an electrode to obtain a mixture film; and positioning the mixed film on at least one surface of a current collector and laminating the mixture to obtain an electrode.

[0163] The above-mentioned items are applicable up to the step of obtaining the conductive material masterbatch (first pulverization step).

[0164] The second mixing step, the second kneading step, and the second pulverizing step are steps for producing a mixed powder for an electrode.

[0165] The mixed powder for an electrode is a powdered electrode material containing an electrode active material, a conductive material, and a binder, and may be obtained by pulverizing a mixture mass containing an electrode active material, an electrode conductive material, and an electrode binder, as described below. In this specification, the mixed powder refers to an aggregate of two or more electrode material particles. Each electrode material particle constituting the mixed powder contains an electrode active material, a conductive material, and a binder.

[0166] The mixed powder for the electrode can be obtained by the following manufacturing method.

[0167] First, an electrode material mixture containing an electrode active material, the conductive material masterbatch prepared above, and a binder polymer (second binder) is prepared. The mixing for preparing the mixture is performed so that the electrode materials, such as the electrode active material, conductive material masterbatch, and electrode binder, are uniformly dispersed within the mixture. Since an electrode according to one embodiment of the present invention is manufactured as a dry electrode without using a solvent, the mixing is performed by mixing the materials in a powder form without adding a solvent. Therefore, the mixing method is not particularly limited as long as it allows simple mixing of the electrode materials, and various methods can be used. For example, the electrode materials can be added to a known device such as a mixer or blender and stirred.

[0168] Next, the electrode material mixture obtained above is subjected to a fiberization process (second kneading step) to fiberize the electrode binder. At this time, the binder indicates at least one of the first binder contained in the conductive material masterbatch and the second binder further added during the production of the mixed powder for the electrode. As the fiberization process, mixing by shear stress, for example, a mechanical milling method or a kneading method, can be applied.

[0169] In one embodiment of the present invention, the fiberization step can be preferably performed using a low-shear kneading method, for example, using a kneading machine such as a kneader. By this kneading, the electrode binder is fiberized, and the electrode materials, such as the electrode active material, which have been added in powder form, are bonded or connected to form a mixture mass. Since the kneading does not involve the addition of a solvent, the mixture mass can have a solid content of 100%.

[0170] In one embodiment of the present invention, the kneading may be controlled at a speed of 10 rpm to 100 rpm. For example, the kneading may be controlled at a speed of 40 rpm or more or 70 rpm or less within the above range. The kneading may be performed for 1 minute to 10 minutes. For example, the kneading may be performed at a speed of 40 rpm to 70 rpm within the above range for 3 minutes to 7 minutes.

[0171] More preferably, the kneading can be performed within 5 minutes or 3 minutes. The lower the tap compressibility of the resulting electrode powder mixture, the more effective the processability of manufacturing an electrode film using the powder. However, the tap compressibility decreases early in the kneading process and remains almost constant after a certain time point. The kneading time within the above range may be preferable in terms of the appropriate degree of fiberization and the tensile strength of the fiberized binder polymer, but the present invention is not limited thereto.

[0172] Meanwhile, in the second kneading step, the shear rate of the kneading can be controlled in the range of 10 / s to 500 / s. In one specific embodiment of the present invention, the kneading can be performed for 1 minute to 30 minutes, and the shear rate can be controlled in the range of 30 / s to 100 / s.

[0173] Furthermore, this kneading step may be performed under high temperature and pressure conditions equal to or greater than atmospheric pressure, more specifically, under pressure conditions higher than atmospheric pressure. More specifically, the kneading may be performed at a temperature in the range of 50°C to 230°C, more specifically, 90°C to 200°C. Kneading within the above-mentioned range may be preferable in terms of the degree of fiberization of the binder polymer, the agglomeration of the input materials, the ease of forming the electrode film, and the tensile strength of the electrode film, but the present invention is not limited thereto.

[0174] The mixing may be performed at atmospheric pressure or higher, specifically, at a pressure of 1 atm to 60 atm, 1 atm to 30 atm, 1 atm to 10 atm, 1 atm to 10 atm, 1.1 atm to 10 atm, 1.1 atm to 6 atm, or 1.1 atm to 3 atm. Mixing within the above-mentioned ranges may be preferable in terms of the degree of crystallization of the fibers and the density of the mixture mass. According to one aspect of the present invention, when a low shear mixing step is performed under high temperature and pressure conditions higher than atmospheric pressure instead of high shear mixing, the intended effects of the present invention can be preferably achieved, but the present invention is not limited thereto.

[0175] Next, the mixture mass produced using the kneading step (second kneading step) is pulverized to obtain a powdered mixture for an electrode (second pulverization step).

[0176] The lump mixture obtained using the kneading process may be immediately pressed and formed into a sheet (calendering process), but in this case, strong pressure and high temperature must be applied to form it into a target thickness, which can cause problems such as the density of the dry electrode film becoming too high or the film not being uniform.For this reason, the lump mixture obtained as described above is pulverized to prepare a mixed powder for an electrode.

[0177] In this case, the pulverization may be performed using equipment such as a blender or grinder, but is not particularly limited thereto. In one embodiment of the present invention, the pulverization may be performed in a grinder at a speed of 5,000 rpm to 20,000 rpm, or 10,000 rpm to 18,000 rpm. Meanwhile, the pulverization step may be performed for 30 seconds to 10 minutes, more specifically, for 30 seconds to 1 minute. While pulverization within the above-mentioned ranges may be preferable in terms of the particle size of the mixed powder for an electrode and the prevention of fine powder generation, the present invention is not limited thereto.

[0178] In one aspect of the present invention, the method may further include classifying the pulverized electrode powder mixture after pulverizing the mixture mass. The classified electrode powder mixture may then be calendered. In the classifying step, the pulverized electrode powder is filtered through a mesh having pores of a certain size or less to remove electrode powder having pores of a certain size or greater.

[0179] The method further includes a step of obtaining a composite film by compressing and molding the electrode powder mixture. In this specification, the process of compressing the electrode powder mixture to manufacture a sheet-shaped dry electrode film is referred to as a calendering process. The calendering process allows the dry electrode film to be prepared in the form of a sheet having a predetermined thickness. For example, the dry electrode film may have a strip shape with an aspect ratio of more than 1. In one embodiment of the present invention, the dry electrode film may have a thickness of 50 μm to 300 μm.

[0180] For example, the calendering process may be performed by a calendering method in which the electrode powder mixture is supplied to a calendering device and thermocompressed using a roll press included in the calendering device. Also, the calendering process may be performed by a roll-to-roll continuous process.

[0181] In one embodiment of the present invention, the calendering device may include a roll press unit having two rollers arranged facing each other, and the electrode powder mixture may be passed through the roll press unit and compressed into a sheet. A plurality of the roll press units may be arranged in series, and compression of the dry electrode film may be performed multiple times. The number of roll press units may be appropriately adjusted taking into account the thickness and rolling ratio of the dry electrode film.

[0182] 1 is a schematic diagram illustrating the calendering process 100. Referring to the diagram, an electrode powder mixture 120 is pressed multiple times by a calendering device including multiple calendering rollers 110 to produce an electrode mixture film 130. The electrode mixture film is produced without using a solvent, and therefore may also be called a dry electrode film.

[0183] Meanwhile, the rotational speed ratio of the rollers in each of the roll press units can be independently controlled within a range of 1:1 to 1:10. For example, the rotational speed ratio of the rollers in one or more of the roll press units can be controlled to a ratio of 1:1 to 1:3. Furthermore, the temperature of the rollers in each of the roll press units can be independently controlled within a range of room temperature (25°C) to 250°C. A composite film can be produced by such a calendering process.

[0184] In one aspect of the present invention, the porosity of the composite film may be 20 vol% to 50 vol%, and preferably controlled to a value of 40 vol% or less or 35 vol% or less within the above range. When the porosity satisfies the above range, it is preferable in terms of achieving a wide variety of effects. In one aspect of the present invention, the porosity can be calculated by the following Equation 2 using the actual density calculated based on the actual density and composition of each component, after measuring the apparent density of the composite film. [Formula 2] Porosity% = {1-(apparent density / actual density)} x 100 …2

[0185] In one embodiment of the present invention, the composite film may have a tensile strength of 0.2 MPa or more. In another embodiment of the present invention, the tensile strength of the composite film may be 0.2 MPa or more, 0.3 MPa or more, or 0.50 MPa or more.

[0186] The tensile strength may be a value measured according to the following method.

[0187] The manufactured film is cut into specimens measuring 1cm x 10cm. In accordance with the American Society for Testing and Materials (ASTM) D638 standard, both ends of the specimen are pulled using a universal testing machine (UTM) (ZwickRoell) under conditions of a preload of 0.01kg / cm and a test speed of 5mm / min. The tensile strength is calculated by dividing the force applied to the specimen at break by the specimen's initial cross-sectional area. Three measurements are taken and the average value is shown.

[0188] After calendering, the resulting composite film is then laminated to form it on at least one surface of a current collector.

[0189] In one aspect of the present invention, the lamination may be a step of rolling and adhering the composite film onto a current collector to a predetermined thickness. The lamination may also be performed using a lamination roll, and in this case, the lamination roll may be maintained at a temperature of room temperature (25°C) to 200°C, but is not limited thereto.

[0190] FIG. 2 is a schematic diagram illustrating a lamination process 200 according to one embodiment of the present invention. Referring to this diagram, an electrode mixture film 230 is bonded to a current collector 220 to produce a dry electrode 240, and the lamination process is performed by pressing with a lamination roller 210. Meanwhile, in the present invention, the electrode mixture film attached to the current collector using lamination may be referred to as an electrode active material layer. Furthermore, in the present invention, the electrode mixture film, i.e., the electrode active material layer, is derived from the electrode powder mixture, and the content ratio of the materials in the electrode active material layer may be in the same range as that of the powder mixture.

[0191] The above-mentioned electrode can be manufactured according to the above method.

[0192] The electrode thus produced can have an electrode resistance of 55 Ω·cm or less.

[0193] Electrochemical elements According to yet another aspect of the present invention, there is provided an electrochemical device including the above-described electrode.

[0194] The electrochemical element includes a positive electrode, a negative electrode, and a separation layer interposed between the positive electrode and the negative electrode, and at least one of the positive electrode and the negative electrode is the electrode described above.

[0195] In one aspect of the present invention, the separation layer may be a typical separation membrane or solid electrolyte membrane used in electrochemical devices, or a component encompassing both of these, and is not particularly limited as long as it is configured to prevent direct contact between the positive electrode and the negative electrode.

[0196] In one aspect of the present invention, the electrochemical device encompasses any device that performs an electrochemical reaction. Specific examples include all types of primary batteries, secondary batteries, fuel cells, solar cells, and capacitors such as supercapacitors. Among the secondary batteries, lithium secondary batteries, including lithium metal secondary batteries, lithium ion secondary batteries, lithium polymer secondary batteries, and lithium ion polymer secondary batteries, are particularly suitable.

[0197] The specific structure of the secondary battery is well known and will not be described in this specification.

[0198] The secondary battery according to the present invention may be included as a unit cell in an energy storage device, but the application of the present invention is not limited thereto.

[0199] The specific structure of the energy storage device is well known and will not be described in this specification.

[0200] The present invention will be described in more detail below with reference to examples. However, the following examples are merely for the purpose of illustrating the present invention, and the scope of the present invention is not limited to these examples.

[0201] Manufacturing example 1. Manufacturing of conductive masterbatch A conductive material masterbatch was produced according to the following method.

[0202] Example 1 PVDF-HFP (melting point 118°C) 40 wt%, PTFE (melting point 348°C) 10 wt%, and CNT (diameter (D 50 )12nm, BET specific surface area 185m 2 % of the cellulose acetate solution (100%) was added to a Super Mixer (20 L Super Mixer, manufactured by Heesung Techwin Co., Ltd., Korea) and mixed at 1,200 rpm for 3 minutes to produce a mixture.

[0203] The resulting mixture was fed to a twin-screw extruder (diameter (Φ) 25, L / D 48) at 2-3 kg / hr via a metering feeder, melt-kneaded at a temperature of 130-200°C in extruder heater #1-9 zones and a screw speed of 400 rpm, and then extruded through a die.

[0204] The obtained extrudate was placed in a blender (manufactured by Shinil Electronics Co., Ltd., Korea) disperser and pulverized at 10,000 rpm for 30 seconds to obtain a conductive material masterbatch.

[0205] Example 2 PVDF (melting point 174°C) 40 wt%, PTFE (melting point 347°C) 10 wt%, and CNT (diameter (D 50 )12nm, BET specific surface area 185m 2 % (100g / g) was added to a super mixer (20L Super Mixer, manufactured by Hisung Techwin Co., Ltd., Korea) and mixed at 1,200 rpm for 3 minutes to produce a mixture.

[0206] The resulting mixture was fed to a twin-screw extruder (diameter (Φ) 25, L / D 48) at 2-3 kg / hr via a metering feeder, melt-kneaded at extruder heater #1-9 zone temperatures of 140-220°C and a screw speed of 400 rpm, and extruded through a die.

[0207] The resulting extrudate was placed in a blender and pulverized at 10,000 rpm for 30 seconds to obtain a conductive material masterbatch.

[0208] Example 3 PVDF (melting point 174°C) 30 wt%, PTFE (melting point 348°C) 10 wt%, and CNT (diameter (D 50 )12nm, BET specific surface area 185m 2 A conductive material masterbatch was obtained in the same manner as in Example 2, except that 60 wt % ( / g) of the cellulose acylate was used.

[0209] Example 4 PVDF-HFP (melting point 118°C) 20 wt%, PTFE (melting point 348°C) 20 wt%, and CNT (diameter (D 50 )12nm, BET specific surface area 185m 2 A conductive material masterbatch was produced in the same manner as in Example 1, except that 60 wt % ( / g) of the conductive material masterbatch was added.

[0210] Comparative Example 1 PVDF-HFP (melting point 118°C) 70 wt% and CNT (diameter (D 50 )12nm, BET specific surface area 185m 2 % (1000 Wt. / g) was placed in a blender (manufactured by Shinil Electronics Co., Ltd., Korea) and mixed at 10,000 rpm for 1 minute to obtain a mixture.

[0211] The temperature of a rotor mixer (PBV-0.1, manufactured by LM TECH, Korea) was stabilized at 160°C, and the mixture obtained above was placed in the rotor mixer and melt-kneaded at a speed of 50 rpm for 10 minutes to obtain a conductive material masterbatch.

[0212] Comparative Example 2 PVDF-HFP (melting point 118°C) 35 wt%, PTFE (melting point 347°C) 35 wt%, and CNT (diameter (D 50 )12nm, BET specific surface area 185m 2 % (wt%) of the mixture was placed in a blender (PBV-0.1, manufactured by Elm Tech, Korea) and mixed at 10,000 rpm for 1 minute to obtain a mixture.

[0213] The temperature of the rotor mixer was stabilized at 160°C, and the mixture obtained above was placed in the rotor mixer, and then melt-kneaded at a speed of 50 rpm for 10 minutes to obtain a mass of mixture.

[0214] The resulting mixture mass was placed in a blender (manufactured by Shinil Electronics Co., Ltd., Korea) disperser and pulverized at 10,000 rpm for 30 seconds to obtain a conductive material masterbatch.

[0215] Comparative Example 3 PVDF-HFP (melting point 118°C) 40 wt%, PTFE (melting point 348°C) 10 wt%, and CNT (diameter (D 50 )12nm, BET specific surface area 185m 2 A conductive material masterbatch was obtained in the same manner as in Comparative Example 2, except that 50 wt % ( / g) of the cellulose acylate was used.

[0216] Evaluation example 1. Evaluation of the physical properties of conductive master batches A photograph of the conductive masterbatch produced above is shown in Figure 1, and an SEM (S-4800, manufactured by Hitachi High-Technologies Corporation) image is shown in Figure 2. For reference, Figure 2 also shows an SEM image of the CNT raw material used in producing the conductive masterbatch.

[0217] Furthermore, the crystallinity of each binder in the conductive masterbatch was measured using a DSC (DSC 25, manufactured by TA Instruments) thermal analysis, and the results are shown in Table 1.

[0218] Crystallinity measurement method 5 to 12 mg of a sample was placed in a differential scanning calorimeter (DSC), and the melting point and heat of fusion (ΔHm) were measured while the temperature was raised at a rate of 10°C / min in a temperature range of 25 to 360°C under a nitrogen atmosphere. The crystallinity was measured using the heat of crystalline fusion (ΔHm°) according to the type of binder as a standard according to the following formula. Crystallinity of binder (Xc) = ΔHm / ΔHm° × 100%

[0219] The 100% crystalline heat of fusion (ΔHm°) of the PVDF binder was 105 J / g, the 100% crystalline heat of fusion (ΔHm°) of the PVDF-HFP binder was 80 J / g, and the 100% crystalline heat of fusion (ΔHm°) of the PTFE binder was measured with reference to a value of 85.4 J / g.

[0220] Evaluation method for CTN dispersibility As shown in Figure 2, the dispersibility was evaluated by measuring the diameter of the CNT bundles and the diameter of the nanofibers in the SEM images.

[0221] [Table 1]

[0222] Referring to the photographs of Examples 1 to 3 and Comparative Examples 1 to 3 shown in FIG. 1, it was confirmed that Comparative Example 1, in which no PTFE binder was used, could not be used as the intended conductive masterbatch because the powdery raw materials did not solidify into lumps.

[0223] Referring to the SEM images of Examples 1 to 3 and Comparative Examples 1 to 3 shown in FIG. 2, it was confirmed that in Comparative Examples 1 and 2, which were produced by kneading using a rotor mixer, the CNTs were not uniformly dispersed, but rather clumped together in bundles.

[0224] According to the results in Table 1, in the case of Comparative Examples 1 to 3, when melt-kneading was performed without using a twin-screw extruder, kneading and extrusion were unstable, and the crystallinity of PTFE was realized to exceed 30%, and it was confirmed that the resulting material could not be used as the intended conductive masterbatch.

[0225] Manufacturing Example 2: Electrode manufacturing Using the conductive material masterbatch produced above, an electrode was produced according to the following method.

[0226] Example 5 The positive electrode active material was lithium nickel cobalt manganese aluminum oxide (NCMA, Li[Ni 0.73 Co 0.05 Mn 0.15 Al 0.02 ]O2), the conductive material masterbatch prepared in Example 1 and polytetrafluoroethylene (PTFE) were added to a blender in a weight ratio of 97:1.6:1.4 and mixed at 10,000 rpm for 1 minute to prepare a mixture. The kneader temperature was stabilized at 180°C, and the mixture was added to the kneader and kneaded at 40 rpm under a pressure of 4 atmospheres to obtain a mixture mass. The mixture mass was added to the blender, pulverized at 10,000 rpm for 30 seconds, and classified using a sieve with 1 mm pores to obtain a mixed powder for an electrode. The crystallinity of PVDF-HFP in the prepared mixed powder for an electrode was 0%, and the crystallinity of PTFE was 6.8%.

[0227] The electrode mixture powder was then placed in a wrap calender (roll diameter: 200 mm, roll temperature: 100°C, roll speed ratio: 1.5) and pressed to produce an electrode mixture film. The electrode mixture film was then placed on both sides of an aluminum thin film (13 μm) and laminated using a roll press with a roll temperature of 30°C to obtain an electrode.

[0228] Example 6 The positive electrode active material was lithium nickel cobalt manganese aluminum oxide (NCMA, Li[Ni 0.73 Co 0.05 Mn 0.15 Al 0.02]O2), an electrode was obtained in the same manner as in Example 5, except that the conductive masterbatch of Example 4 and polytetrafluoroethylene (PTFE) were used in a weight ratio of 97:1.34:1.66.

[0229] At this time, the crystallinity of PVDF-HFP in the manufactured mixed powder for electrodes was 0%, and the crystallinity of PTFE was 10.6%.

[0230] Comparative Example 3 An electrode was obtained in the same manner as in Example 5, except that the conductive material masterbatch of Comparative Example 3 was used as the conductive material masterbatch.

[0231] At this time, the crystallinity of PVDF-HFP in the manufactured mixed powder for electrodes was 0%, and the crystallinity of PTFE was 15.6%.

[0232] Comparative Example 4 The positive electrode active material was lithium nickel cobalt manganese aluminum oxide (NCMA, Li[Ni 0.73 Co 0.05 Mn 0.15 Al 0.02 ]O2) 96.3 wt%, PTFE (melting point 348°C) 2.2 wt% and carbon black (BET specific surface area 65 m 2 % (1.5 wt %) of the cellulose acetate solution (1.5 wt %) was added to a super mixer (20 L Super Mixer, manufactured by Hisung Techwin Co., Ltd., Korea) and mixed at 1,200 rpm for 3 minutes to produce a mixture.

[0233] The temperature of the kneader was stabilized at 180°C, and the mixture was placed in the kneader, followed by kneading for 7 minutes at a speed of 40 rpm under a pressure of 4 atmospheres to obtain a mass of the mixture.

[0234] Thereafter, an electrode was obtained in the same manner as in Example 5.

[0235] Evaluation Example 2: Evaluation of the composition of mixed powder for electrodes and the crystallinity of electrode binders The compositions of the mixed powders for electrodes used in the manufacture of the electrodes of Examples 5, 6, Comparative Examples 3 and 4 are summarized in Table 2 below.

[0236] In addition, the crystallinity of the electrode binder contained in the prepared electrode powder mixture was measured, and the results are shown in Table 2 below.

[0237] The crystallinity of the binder was measured in the same manner as in Evaluation Example 1, as follows:

[0238] [Table 2]

[0239] As is clear from Table 2 above, it was confirmed that the use of a CNT conductive material masterbatch can reduce the conductive material content in the mixed powder for an electrode and increase the active material content.

[0240] In addition, when using a CNT conductive material masterbatch, it was confirmed that the crystallinity of the electrode binder in the mixed powder for electrodes in Examples 5 and 6, which used a twin-screw extruder, was 15% or less, compared to Comparative Example 3, which used a rotor mixer in the melt-kneading stage.

[0241] Evaluation example 3: Evaluation of electrode properties The tensile strength of the electrode mixture films and the resistance values ​​of the electrodes produced in Example 1, Example 2, Comparative Example 1, and Comparative Example 2 are shown in Table 3 below.

[0242] Table 3 below also shows the electrode resistance values ​​converted based on a content of 1% by weight of the conductive material.

[0243] Measurement of tensile strength of electrode mixture film The manufactured film was cut into a specimen measuring 1 cm x 10 cm in length and width. In accordance with the American Society for Testing and Materials (ASTM) D638 standard, both ends of the specimen were pulled using a universal testing machine (UTM) (manufactured by ZwickRoell) under conditions of a preload of 0.01 kg / cm and a test speed of 5 mm / min.

[0244] The tensile strength was calculated by dividing the force applied to the specimen at the time of breakage by the initial cross-sectional area of ​​the specimen. The tensile strength was measured three times and shown as an average value.

[0245] Electrode resistance measurement The prepared electrode sample was placed in a multi-probe tester (RM2610, manufactured by Hioki E.E. Corporation), and the potential difference measured between each of the 45 probes was measured under conditions of a positive current of 100 μA, a negative current of 10 mA, and a voltage of 0.5 V, and this was expressed as the electrode resistance value.

[0246] Electrode resistance conversion The electrode resistance value measured according to the following formula 1 was converted based on 1% by weight of the conductive material. [Formula 1] Rt = Cw × Rw …1

[0247] In the above formula, Rt represents the electrode resistance value converted based on 1 wt % of the conductive material, Cw represents the content of the conductive material based on the total weight of the electrode active material layer in the target electrode, and Rw represents the electrode resistance value of the target electrode.

[0248] [Table 3]

[0249] According to Table 3 above, it was confirmed that in Examples 5 and 6, in which a CNT conductive material masterbatch was used in the production of an electrode composite film, the electrode resistance value was significantly improved while the tensile strength was well maintained at 0.2 MPa or more.

[0250] In particular, Examples 5 and 6 exhibited electrode resistance values ​​of 55 Ω cm or less despite containing less than 1 wt % of conductive material. When the electrode resistance values ​​of Examples 5 and 6 were converted based on a conductive material content of 1 wt %, it was confirmed that the electrode resistance values ​​were significantly improved compared to Comparative Examples 3 and 4.

[0251] As described above, in the case of Examples 5 and 6, it was confirmed that the electrode resistance value was significantly improved, and this was attributed to the fact that the use of a CNT conductive material masterbatch in the production of the mixed powder for electrodes and the composite film for electrodes improved the dispersibility of the conductive material with a large BET specific surface area, reduced the crystallinity of the binder in the mixed powder for electrodes, and increased the content of the active material.

[0252] The present invention has been described above with reference to the embodiments and drawings. However, a person having ordinary knowledge in the technical field to which the present invention pertains should be able to make a wide variety of applications and modifications within the scope of the present invention based on the above content. [Explanation of symbols]

[0253] 100 Calendering process 110 Calendaring Rollers 120 Mixed powder for electrodes 130 Electrode composite film 200 Lamination process 210 Lamination Roller 220 Current Collector 230 Electrode mixture film 240 Dry Electrode

Claims

1. The conductive material includes a polyvinylidene fluoride (PVDF) binder and a polytetrafluoroethylene (PTFE) binder, The conductive material is 80 m ２ / g or more BET specific surface area, The conductive material masterbatch, wherein the polyvinylidene fluoride (PVDF) binder and the polytetrafluoroethylene (PTFE) binder each have a degree of crystallinity of 30% or less.

2. The conductive material masterbatch according to claim 1 , wherein the conductive material comprises carbon nanotubes alone, or the conductive material comprises carbon nanotubes and dot-like conductive materials.

3. The conductive material includes carbon nanotubes and dot-like conductive material; The conductive material masterbatch according to claim 2 , wherein the dot-like conductive material is carbon black, activated carbon, graphite, or a mixture of two or more of these.

4. 3. The conductive material masterbatch according to claim 2, wherein the weight ratio of the carbon nanotubes to the dot-like conductive material is 100:0 to 10:

90.

5. The conductive material masterbatch according to claim 2 , wherein the carbon nanotubes are dispersed in the form of nanofibers.

6. 3. The conductive material masterbatch according to claim 2, wherein the carbon nanotubes have a diameter of 0.1 to 50 nm.

7. 2. The conductive material masterbatch according to claim 1, wherein the polyvinylidene fluoride (PVDF)-based binder comprises polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), or a mixture thereof.

8. 2. The conductive material masterbatch according to claim 1, comprising 20 to 70 parts by weight of the conductive material, 5 to 60 parts by weight of the polyvinylidene fluoride (PVDF) binder, and 0.1 to 50 parts by weight of the polytetrafluoroethylene (PTFE) binder.

9. a current collector; and an electrode active material layer formed on at least one surface of the current collector, the electrode active material layer includes an electrode active material, an electrode conductive material, and an electrode binder; the electrode binder is fibrous to bind the electrode active material and the electrode conductive material, having an electrode resistance of 55 Ω cm or less, The electrode conductive material includes carbon nanotubes alone, or the electrode conductive material includes carbon nanotubes and dot-like conductive materials; The electrode, wherein the electrode conductive material comprises a carbon material having a BET specific surface area of ​​80 m 2 / g or more.

10. The electrode of claim 9 , wherein the content of the electrode conductive material is 1 wt % or less based on the total weight of the electrode active material layer.

11. 10. The electrode of claim 9, wherein the electrode binder has a crystallinity of 15% or less.

12. The electrode of claim 9 , wherein the content of the electrode active material is 95 wt % or more based on the total weight of the electrode active material layer.

13. the electrode conductive material includes carbon nanotubes and dot-like conductive materials; 10. The electrode according to claim 9, wherein the dot-like conductive material is carbon black, activated carbon, graphite, or a mixture of two or more of these.

14. 10. The electrode according to claim 9, wherein the weight ratio of the carbon nanotubes to the conductive dots is 100:0 to 10:

90.

15. 10. The electrode according to claim 9, wherein the electrode conductive material and the electrode binder are derived from the conductive material masterbatch according to any one of claims 1 to 8.

16. A method for producing a conductive material masterbatch, Mixing a conductive material, a polyvinylidene fluoride (PVDF) binder, and a polytetrafluoroethylene (PTFE) binder to obtain a mixture; kneading and extruding the mixture to obtain an extrudate; and grinding the extrudate, The conductive material is 80 m ２ / g or more BET specific surface area, A method for producing a conductive material masterbatch, wherein the polyvinylidene fluoride (PVDF) binder and the polytetrafluoroethylene (PTFE) binder in the produced conductive material masterbatch each have a degree of crystallinity of 30% or less.

17. The method for producing a conductive material masterbatch according to claim 16, wherein the step of obtaining the mixture comprises mixing in a mixer at 200 rpm to 1,700 rpm for 1 minute to 30 minutes.

18. 17. The method for producing a conductive material masterbatch according to claim 16, wherein the step of obtaining an extrudate comprises feeding the mixture into a twin-screw extruder, melt-kneading the mixture at an extrusion temperature of 100°C to 300°C and a screw speed of 50 rpm to 600 rpm, and extruding the mixture through a die.

19. The method for producing a conductive material masterbatch according to claim 16, wherein the pulverization is carried out at 500 rpm to 20,000 rpm for 5 seconds to 10 minutes.

20. A method for manufacturing the electrode according to claim 9, comprising: mixing a conductive material and a first binder to obtain a mixture; kneading and extruding the mixture to obtain an extrudate; grinding the extrudate to obtain a conductive material masterbatch; forming an electrode active material layer on at least one surface of a current collector from a mixture including an electrode active material, the conductive material masterbatch, and a second binder.

21. The step of forming the electrode active material layer includes: mixing the electrode active material, the conductive material masterbatch, and the second binder to obtain a mixture; kneading the obtained mixture at a high temperature and a low shear rate to obtain a mixture mass; grinding the mixture mass under high shear to obtain a mixed powder for an electrode; calendering the electrode powder mixture to obtain a composite film; The method for manufacturing an electrode according to claim 20 , further comprising: a step of positioning the composite film on at least one surface of the current collector and laminating the composite film.

22. The method for producing an electrode according to claim 20, wherein the crystallinity of the first binder is 30% or less.

23. The method for producing an electrode according to claim 21 , wherein the composite film has a tensile strength of 0.2 MPa or more.

24. The method for producing an electrode according to claim 20, wherein the produced electrode has an electrode resistance of 55 Ω·cm or less.

25. a positive electrode, a negative electrode, and a separation layer interposed between the positive electrode and the negative electrode; An electrochemical element, wherein at least one of the positive electrode and the negative electrode is the electrode according to claim 9 .

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