Electrode, manufacturing method thereof, and lithium secondary battery comprising same

Abstract

Disclosed are an electrode, a manufacturing method thereof, and a lithium secondary battery comprising same, the electrode comprising: an electrode current collector; and an electrode active material layer formed on at least one surface of the electrode current collector, wherein the electrode active material layer comprises an electrode active material and a first conductive material-first binder composite, the first conductive material comprising carbon nanotubes, and the first binder having a complex viscosity of 1,500 Pa·s or lower at 170°C and 0.1 Hz.

Description

Electrode, method of manufacturing the same, and lithium secondary battery including the same

[0001] The present invention relates to an electrode, a method for manufacturing the same, and a lithium secondary battery including the same. Specifically, the invention relates to an electrode having excellent electrochemical performance with improved conductive material dispersibility and binder flowability, a method for manufacturing the same, and a lithium secondary battery including the same.

[0002] This application claims priority based on Korean Application No. 10-2024-0152842 filed on October 31, 2024, and all contents disclosed in the specification of said application are incorporated into this application.

[0003] Recently, interest in energy storage technology has been steadily increasing. As application fields expand to include energy for mobile phones, camcorders, laptop PCs, and even electric vehicles, there is a growing demand for higher energy density in batteries used as power sources for these electronic devices. Lithium-ion batteries are the best batteries to meet these demands, and active research is currently underway in this area.

[0004] Such lithium secondary batteries generally include a positive electrode made of lithium metal oxide, a negative electrode made of carbon material, an electrolyte containing a lithium salt and an organic solvent, and a separator interposed between the positive and negative electrodes to electrically insulate them.

[0005] Currently, the positive electrode of a lithium secondary battery is manufactured by mixing an active material, a conductive material, and an N-methyl-2-pyrrolidone (NMP) solvent with poly(vinylidene fluoride) (PVdF) as a binder to form a slurry, which is then coated onto a current collector. However, halogen-based PVdF binders have problems such as gas generation or electrode delamination during charging and discharging under high temperature and high voltage. Additionally, NMP, which is used as a solvent, is harmful to the environment and requires recovery facilities. Furthermore, it has a high boiling point of 200°C, making it difficult to ensure processability. Moreover, defects such as cracks may occur in the active material layer as the solvent evaporates during the drying process of the slurry coated on the current collector.

[0006] Recently, research on manufacturing solvent-free dry electrodes is actively underway.

[0007] Dry electrodes are manufactured by thoroughly mixing active materials, conductive agents, and binders dry without solvents. Among these, carbon black is used as the conductive agent for manufacturing dry electrodes; however, the reality is that the use of carbon nanotubes, such as MWCNTs with excellent conductivity, is limited due to the difficulty of dispersion.

[0008] In addition, the binder used to bind the electrode active material and the conductive material acts as a resistor within the electrode.

[0009] Therefore, there is still a need to develop electrodes with improved electrical conductivity characteristics by improving the dispersibility of linear conductive materials, such as carbon nanotubes, in dry electrodes and reducing the resistance of the binder.

[0010] The problem to be solved by the present invention is to provide an electrode having excellent electrochemical performance with improved conductive material dispersibility and binder flowability, a method for manufacturing the same, and a lithium secondary battery including the same.

[0011] In order to solve the problem of the present invention, an electrode of the following embodiment, a method for manufacturing the same, and a lithium secondary battery including the same are provided.

[0012] According to the first embodiment,

[0013] The electrode current collector; and an electrode active material layer formed on at least one surface of the electrode current collector, comprising

[0014] The above electrode active material layer comprises an electrode active material and a first conductive material-first binder composite, and

[0015] The above first conductive material includes carbon nanotubes, and

[0016] An electrode is provided characterized in that the first binder has a composite viscosity of 1,500 Pa·s or less at 170°C and 0.1 Hz.

[0017] According to the second embodiment, in the first embodiment,

[0018] The first binder may have a composite viscosity of 0.01 Pa·s to 1,500 Pa·s at 170°C and 0.1 Hz.

[0019] According to the third embodiment, in the first embodiment or the second embodiment,

[0020] The above first conductive material-first binder composite may include a first binder and a first conductive material bonded to the surface of the first binder.

[0021] According to the fourth embodiment, in any one of the first to third embodiments,

[0022] The first binder above may include a polyolefin-based polymer.

[0023] According to the fifth embodiment, in any one of the first to fourth embodiments,

[0024] The first binder may include polyethylene, polypropylene, polybutylene, polypentene, or two or more of these.

[0025] According to the 6th embodiment, in any one of the 1st to 5th embodiments,

[0026] The weight-average molecular weight of the first binder may be 5,000 g / mol to 200,000 g / mol.

[0027] According to the seventh embodiment, in any one of the first to sixth embodiments,

[0028] The weight ratio of the first conductive material and the first binder in the above first conductive material-first binder composite may be 1:99 to 30:70.

[0029] According to the eighth embodiment, in any one of the first to seventh embodiments,

[0030] The above electrode active material layer may further include one or more of the second conductive material and the second binder.

[0031] According to the ninth embodiment, in the eighth embodiment,

[0032] The above second binder may include polytetrafluoroethylene.

[0033] According to the 10th embodiment, in the 8th or 9th embodiment,

[0034] The weight ratio of the first binder and the second binder may be 10:90 to 90:10.

[0035] According to the 11th embodiment, in any one of the 1st to 10th embodiments,

[0036] The above electrode active material layer may comprise 90 to 80 parts by weight of an electrode active material and 3 to 20 parts by weight of a first conductive material-first binder composite.

[0037] According to the 12th embodiment, in any one of the 8th to 11th embodiments,

[0038] The electrode active material layer may comprise 90 to 80 parts by weight of electrode active material, 0.5 to 10 parts by weight of a first conductive material-first binder composite, 0.5 to 5 parts by weight of a second binder, and 0.5 to 5 parts by weight of a second conductive material.

[0039] According to the 13th embodiment,

[0040] A lithium secondary battery comprising a positive electrode; a negative electrode; a separator disposed between the positive electrode and the negative electrode; and an electrolyte,

[0041] A lithium secondary battery is provided, characterized in that at least one of the above positive and negative electrodes is an electrode according to any one of the first to twelfth embodiments.

[0042] According to the 14th embodiment,

[0043] A step of preparing a mixture by dry mixing and kneading the electrode active material and the first conductive material-first binder composite without a solvent;

[0044] A step of grinding the above mixture;

[0045] A step of manufacturing an electrode sheet by feeding the above-mentioned crushed product between a plurality of rolls and calendering it; and

[0046] A method for manufacturing an electrode according to any one of the first to twelfth embodiments is provided, comprising the step of laminating the electrode sheet on at least one surface of a current collector.

[0047] According to the 15th embodiment, in the 14th embodiment,

[0048] The above first conductive material-first binder composite

[0049] It can be formed by dry fusing the first conductive material and the first binder so that the first conductive material is bonded to the surface of the first binder.

[0050] According to the 16th embodiment, in the 14th embodiment or the 15th embodiment,

[0051] The above dry fusion can be carried out at a speed of 1,000 to 9,000 rpm for a period of 5 to 60 minutes.

[0052] According to the 17th embodiment, in any one of the 14th to 16th embodiments,

[0053] The step of preparing the above mixture may include a step of mixing and kneading dry without a solvent, additionally including one or more of a second conductive material and a second binder in addition to the electrode active material and the first conductive material-first binder composite.

[0054] According to one embodiment of the present invention, by compounding a conductive material containing carbon nanotubes with a binder, the conductivity of the electrode is greatly increased by improving the dispersibility of the conductive material while simultaneously imparting conductivity to the binder, and the processability of the electrode manufacturing is improved by improving the flowability of the binder to alleviate clumping when the binder is added, and the content of the conductive material is optimized to provide an electrode having excellent energy density and electrochemical characteristics, and a lithium secondary battery including the same.

[0055] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the description of the invention; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. Meanwhile, the shape, size, scale, or ratio of elements in the drawings included in this specification may be exaggerated to emphasize a clearer explanation.

[0056] Figure 1 is a photograph of the first conductive material-first binder composite of Example 2 before and after preparation.

[0057] Figure 2 is a graph showing the results of powder resistance evaluation of the first conductive material-first binder composite prepared in Examples 1, 2, and 3, carbon black, and multi-walled carbon nanotube (MWCNT) conductive material alone.

[0058] Hereinafter, the present invention will be described in detail with reference to the drawings. Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, and should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0059] Therefore, the embodiments described in this specification and the configurations described in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0060] Furthermore, throughout the specification, when a part is described as "include, comprise," "have," or "possess" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0061] Throughout this specification, the description of 'A and / or B' means 'A or B or both.'

[0062] Throughout the entire specification, unless otherwise specifically stated, temperature refers to Celsius temperature, and the unit is °C.

[0063] In this specification, "particle size Dn" refers to the particle size at the n% point of the cumulative distribution of the number of particles according to particle size. That is, D50 is the particle size at the 50% point of the cumulative distribution of the number of particles according to particle size, D90 is the particle size at the 90% point of the cumulative distribution of the number of particles according to particle size, and D10 is the particle size at the 10% point of the cumulative distribution of the number of particles according to particle size. The above Dn can be measured using the laser diffraction method. Specifically, after dispersing the powder to be measured in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (Malvern; mastersizer 3000) and the difference in diffraction patterns according to particle size is measured as the particles pass through the laser beam to calculate the particle size distribution. D10, D50, and D90 can be measured by calculating the particle diameter at the point where the cumulative distribution of the number of particles according to the particle size in the measuring device reaches 10%, 50%, and 90%.

[0064] In this specification, unless otherwise specified, complex viscosity is measured using an Advanced Rheometric Expansion System (ARES-G2) at 170°C and with the frequency changed stepwise from 0.01 Hz to 100 Hz. Additionally, it is measured at a strain (1% to 10%) in a range where linear viscoelastic properties can be secured according to the viscosity of each polymer.

[0065] In this specification, the melt index (melt flow index, MFI) is measured under conditions of 230°C and 2.16 kg according to ASTM D-1238 unless otherwise specified.

[0066]

[0067] According to one aspect of the present invention,

[0068] The electrode current collector; and an electrode active material layer formed on at least one surface of the electrode current collector, comprising

[0069] The above electrode active material layer comprises an electrode active material and a first conductive material-first binder composite, and

[0070] The above first conductive material includes carbon nanotubes, and

[0071] An electrode is provided characterized in that the first binder has a composite viscosity of 1,500 Pa·s or less at 170°C and 0.1 Hz.

[0072]

[0073] In order to improve upon the issue where the dispersibility of carbon nanotubes is significantly reduced and the conductivity of the electrode is compromised when conventional linear conductive materials, such as carbon nanotubes, are simply mixed to manufacture an electrode composite, the electrode of the present invention pre-combines a first conductive material containing carbon nanotubes with a first binder, thereby greatly improving the dispersibility of the first conductive material and enabling the uniform formation of an electron conduction network within the electrode active material layer.

[0074] According to one embodiment of the present invention, the first conductive material-first binder composite may include a first binder and a first conductive material bonded to the surface of the first binder.

[0075] At this time, the first conductive material comprises carbon nanotubes, and may include carbon nanotubes including, for example, single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, etc.

[0076] The first binder has a composite viscosity of 1,500 Pa·s or less at 170°C and 0.1 Hz. In one embodiment of the present invention, the first binder may have a composite viscosity of 0.01 Pa·s to 1,500 Pa·s, or 1 Pa·s to 200 Pa·s, or 3 Pa·s to 150 Pa·s, or 0.01 Pa·s to 18 Pa·s, or 18 Pa·s to 1,500 Pa·s, or 1 Pa·s to 18 Pa·s, or 3 Pa·s to 18 Pa·s, or 18 Pa·s to 200 Pa·s, or 18 Pa·s to 150 Pa·s at 170°C and 0.1 Hz.

[0077] When the first binder has a composite viscosity of more than 1,500 Pa·s at 170°C and 0.1 Hz, the mechanical properties of the electrode sheet are weak during the electrode manufacturing process, making it difficult to manufacture the electrode.

[0078] In one embodiment of the present invention, the melt index (MI) of the first binder is 100 g / 10 min or more, or 200 g / 10 min or more, or 300 g / 10 min or more, or 400 g / 10 min or more, or 500 g / 10 min or more, or 600 g / 10 min or more, or 700 g / 10 min or more, or 800 g / 10 min or more, or 900 g / 10 min or more, or 1000 g / 10 min or more, or 1300 g / 10 min or more, or 1500 g / 10 min or more, or 100 g / 10 min to 3000 g / 10 min, or 100 g / 10 min to 2000 g / 10 min, or 100 g / 10 min to 1800 g / 10 min, or 200 g / 10min to 1800g / 10min, or 300 g / 10min to 1800g / 10min, or 400 g / 10min to 1800g / 10min, or 500 g / 10min to 1800g / 10min, or 600 g / 10min to 1800g / 10min, or 700 g / 10min to 1800g / 10min, or 800 g / 10min to 1800g / 10min, or 900 g / 10min to 1800g / 10min, or 1000 g / 10min to 1800g / 10min, or 1300 g / 10min to 1800g / 10min, or 1500 g / 10min to 1800g / 10min, or 1800 It can be g / 10min to 2000g / 10min, or 1800g / 10min to 3000g / 10min. If the melt index of the first binder falls within the above range, it may be advantageous for the mechanical properties of the electrode sheet.

[0079] In one embodiment of the present invention, the first binder may include a polyolefin-based polymer, for example, polyethylene, polypropylene, polybutylene, polypentene, or two or more of these.

[0080] In one embodiment of the present invention, the weight-average molecular weight of the first binder may be 5,000 g / mol to 200,000 g / mol, or 7,000 g / mol to 100,000 g / mol, or 10,000 g / mol to 70,000 g / mol. When the weight-average molecular weight of the first binder falls within the above range, it may have an appropriate composite viscosity, thereby improving the tensile strength of the electrode sheet.

[0081] The above weight-average molecular weight can be measured by gel permeation chromatography (GPC).

[0082] Specifically, the number average molecular weight (Mn) and weight average molecular weight (Mw) of the first binder can be measured under the following conditions using gel permeation chromatography (GPC: gel permeation chromatography, PL GPC220, Agilent Technologies), respectively, and the molecular weight distribution can be calculated by dividing the weight average molecular weight by the number average molecular weight.

[0083] - Column: PL Olexis (Polymer Laboratories)

[0084] - Solvent: TCB (Trichlorobenzene)

[0085] - Flow rate: 1.0 ml / min

[0086] - Sample concentration: 1.0 mg / ml

[0087] - Injection volume: 200 µl

[0088] - Column temperature: 160℃

[0089] - Detector: Agilent High Temperature RI detector

[0090] - Standard: Polystyrene (corrected by a cubic function)

[0091]

[0092] In one embodiment of the present invention, the weight ratio of the first conductive material and the first binder in the first conductive material-first binder composite may be 5:95 to 50:50, or 5:95 to 30:70, or 5:95 to 15:85. When the weight ratio of the first conductive material and the first binder satisfies these ranges, the content of the first conductive material is optimized so that the conductivity of the first binder can be improved, which may be advantageous in terms of battery performance.

[0093] According to one embodiment of the present invention, the electrode active material layer may further include one or more of a second conductive material and a second binder as needed.

[0094] Accordingly, the electrode active material layer may include an electrode active material, a first conductive material-first binder composite, and a second conductive material, or may include an electrode active material, a first conductive material-first binder composite, and a second binder, or may include an electrode active material, a first conductive material-first binder composite, a second conductive material, and a second binder.

[0095] The second binder above may include polypolytetrafluoroethylene.

[0096] When the above polypolytetrafluoroethylene is subjected to shear force, it becomes fiberized and can bind the electrode active material, the first conductive material-first binder composite, and the second conductive material included in the electrode active material layer, thereby serving to improve the adhesion strength with the current collector. In addition, the polypolytetrafluoroethylene has excellent elongation in the longitudinal direction, which can improve the flexibility of the electrode active material layer and the electrode itself containing it.

[0097] In one embodiment of the present invention, the second binder may further include a binder polymer commonly used in the art in addition to polytetrafluoroethylene.For example, the binder polymer is styrene butadiene rubber (SBR), butadiene rubber (BR), nitrile butadiene rubber (NBR), styrene butadiene styrene block polymer (SBS), styrene ethylene butadiene block polymer (SEB), styrene-(styrene butadiene)-styrene block polymer, natural rubber (NR), isoprene rubber (IR), ethylene-propylene-diene terpolymer (EPDM), poly(ethylene-co-propylene-co-5-methylene-2-norbornene), polyvinylidene fluoride, polyvinyl chloride, polyvinylidene fluoride-co-hexafluoropropylene, or polyvinylidene fluoride-trichloroethylene. (polyvinylidene fluoride-co-trichloroethylene), polymethylmethacrylate, polyethylhexyl acrylate, polybutyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene, polypropylene, ethylene vinyl acetate copolymer (polyethylene-co-vinyl acetate), polyethylene oxide, polypropylene oxide, polyarylate, cyanoethylpullulan, cyanoethylpolyvinyl alcohol, or may include two or more of these.

[0098] In one embodiment of the present invention, the weight ratio of the first binder and the second binder may be 10:90 to 90:10, or 20:80 to 80:20, or 30:70 to 30:70. When the weight ratio of the first binder and the second binder satisfies these ranges, it may be advantageous in terms of the processability of the electrode and the mechanical strength of the electrode sheet.

[0099] In one embodiment of the present invention, the second conductive material is not particularly limited as long as it possesses conductivity without causing chemical changes in the battery. Non-limiting examples thereof include graphite such as natural graphite or artificial graphite; carbon black-based carbon compounds such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers or metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskey such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0100] In one embodiment of the present invention, the electrode active material layer may comprise 90 to 80 parts by weight of an electrode active material, or 97 to 90 parts by weight, and 3 to 20 parts by weight of a first conductive material-first binder composite, or 3 to 10 parts by weight.

[0101] Alternatively, the electrode active material layer may comprise 90 to 80 parts by weight of electrode active material, or 97 to 90 parts by weight, 1 to 10 parts by weight of a first conductive material-first binder composite, or 1 to 5 parts by weight, and 0.5 to 5 parts by weight of a second conductive material, or 0.5 to 3 parts by weight.

[0102] Alternatively, the electrode active material layer may comprise 90 to 80 parts by weight of electrode active material, or 97 to 90 parts by weight, 0.5 to 10 parts by weight of a first conductive material-first binder composite, or 0.5 to 5 parts by weight, and 0.5 to 5 parts by weight of a second binder, or 0.5 to 3 parts by weight.

[0103] Alternatively, the electrode active material layer may comprise 90 to 80 parts by weight of electrode active material, or 97 to 90 parts by weight, 0.5 to 10 parts by weight of a first conductive material-first binder composite, or 0.5 to 5 parts by weight, 0.5 to 5 parts by weight of a second binder, or 0.5 to 3 parts by weight, 0.5 to 5 parts by weight of a second conductive material, or 0.5 to 3 parts by weight.

[0104] When the content of the electrode active material, the first conductive material-first binder composite, the second conductive material, and the second binder in the above electrode active material layer satisfies this range, it may be advantageous in terms of processability of the electrode and mechanical strength of the electrode sheet.

[0105] In one embodiment of the present invention, the electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, the current collector may be made of stainless steel, aluminum, nickel, titanium, calcined carbon, copper, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. The current collector may also have fine irregularities formed on its surface to increase the adhesion of the active material, and may take various forms such as a film, sheet, foil, net, porous body, foam, or nonwoven fabric. Meanwhile, in one embodiment of the present invention, the current collector may have a thickness of 10 μm to 50 μm, but is not particularly limited thereto. For example, the current collector may have a thickness of 10 μm to 20 μm.

[0106] In one embodiment of the present invention, the electrode active material may be a positive electrode active material. The positive electrode active material is not limited to specific components as long as it can be used as a positive electrode active material for a lithium-ion secondary battery. Non-limiting examples thereof include layered compounds such as lithium manganese complex oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or compounds substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 ~ 0.3); chemical formula LiMn 2-x M x Lithium manganese composite oxides represented by O2 (where M = Co, Ni, Fe, Cr, Zn, or Ta, and x = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu, or Zn); Li in which part of the Li in the chemical formula is substituted with aluminum ions. 1+x (Ni a Co b Mn c Al d ) 1-x O2(x = 0 ~ 0.03, a = 0.3 ~ 0.95, b = 0.01 ~ 0.35, c = 0.01 ~ 0.5, d = 0.001 ~ 0.03, a+b+c+d=1); disulfide compound; may include one or a mixture of two or more of Fe2(MoO4)3.

[0107] In one embodiment of the present invention, the electrode active material may be a negative electrode active material. As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; and SiO β Examples include metal oxides capable of doping and dedoping lithium, such as (0 < β < 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the metal compound and carbonaceous material, such as Si-C composites or Sn-C composites, and any one or more of these may be used. Additionally, a metallic lithium thin film may be used as the negative electrode active material. Furthermore, the carbon material may include low-crystallinity carbon and high-crystallinity carbon. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0108] In one embodiment of the present invention, the thickness of the electrode active material layer may be, for example, 10 to 250 μm, or 50 to 150 μm.

[0109] In this specification, unless otherwise defined, the thickness of the electrode active material layer may be measured using means known in the art for measuring the thickness of each component, such as a thickness gauge or SEM image. In one embodiment of the present invention, the thickness of the electrode active material layer may be measured using a thickness gauge (Mitutoyo, VL-50S-B), but is not limited thereto.

[0110]

[0111] According to one aspect of the present invention,

[0112] A lithium secondary battery comprising a positive electrode; a negative electrode; a separator disposed between the positive electrode and the negative electrode; and an electrolyte,

[0113] A lithium secondary battery is presented in which at least one of the above positive and negative electrodes is an electrode according to one embodiment of the present invention described above.

[0114] The above lithium secondary battery may include a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.

[0115] A separator applied to a lithium secondary battery according to one embodiment of the present invention is not particularly limited and may be composed solely of a porous polymer substrate, or may comprise a porous polymer substrate; and an organic-inorganic composite porous layer formed on at least one surface of the porous polymer substrate and comprising a plurality of inorganic particles and a binder polymer. The separator is interposed between the positive electrode and the negative electrode and serves to insulate the positive electrode and the negative electrode.

[0116] Any porous polymer substrate commonly used in the field may be used as the above porous polymer substrate. For example, a polyolefin-based porous polymer membrane or a nonwoven fabric may be used as the above porous polymer substrate, but is not particularly limited thereto.

[0117] The above-mentioned polyolefin-based porous polymer membrane may be a polyolefin-based polymer such as high-density polyethylene, linear low-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, polybutylene, polypentene, or a membrane formed from two or more of these.

[0118] In addition to polyolefin-based nonwoven fabrics, the above nonwoven fabric may be, for example, polyethyleneterephthalate, polybutyleneterephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenyleneoxide, polyphenylenesulfide, polyethylenenaphthalene, or a nonwoven fabric formed from two or more of these. The structure of the nonwoven fabric may be a spunbond nonwoven fabric or a melt-blown nonwoven fabric composed of long fibers.

[0119] The thickness of the porous polymer substrate is not particularly limited, but may be 3 μm to 50 μm, or 3 μm to 15 μm. The pore size and porosity present in the porous polymer substrate are also not particularly limited, but may be 0.01 μm to 50 μm and 10% to 95%, respectively.

[0120] In one embodiment of the present invention, the inorganic particles are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in the present invention are suitable for the operating voltage range of the battery to which they are applied (e.g., Li / Li). +It is not particularly limited as long as oxidation and / or reduction reactions do not occur at a voltage of 0 to 5V (based on a reference). The inorganic particles may include high-dielectric inorganic particles having a dielectric constant of 5 or more, or 10 or more, inorganic particles having lithium-ion transport capability, or two or more of these. Inorganic particles having a dielectric constant of 5 or more include BaTiO3, BaSO4, Pb(Zr,Ti)O3 (PZT), and Pb 1-x La x Zr 1-y Ti y O3(PLZT, where, 0 <x<1 , 0<y<1임), Pb(Mg 1 / 3 Nb 2 / 3 O3-PbTiO3(PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, Mg(OH)2, NiO, CaO, ZnO, ZrO2, Y2O3, SiO2, Al2O3, γ-AlOOH, Al(OH)3, SiC, TiO2, or a mixture of two or more of these may be used, but is not limited thereto.

[0121] In one embodiment of the present invention, the size of the inorganic particles is not limited, but in order to form an organic-inorganic composite porous layer of uniform thickness and an appropriate porosity, they may have an average particle size in the range of 0.01 to 10 μm or 0.05 to 1.0 μm. In this case, the average particle size of the inorganic particles refers to the particle size (D50) of the cumulative value from the small particle size side, calculated based on the measurement results of measuring the particle size distribution of the particles after classification by a general particle size distribution meter. This particle size distribution can be measured by laser diffraction analysis.

[0122] In one embodiment of the present invention, the binder polymer included in the separator is polyvinylidene fluoride (PVdF), polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polyvinylidene fluoride-co-chlorotrifluoroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate It may include, but is not limited to, propionate (cellulose acetate propionate), cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethyl cellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide, or two or more of these.

[0123] In one embodiment of the present invention, the content ratio of inorganic particles and binder polymer included in the separation membrane may be 20:80 to 99.9:0.1, 50:50 to 99.5:0.5, or 70:30 to 80:20. When the content ratio of inorganic particles and binder polymer is within the aforementioned range, sufficient adhesion between inorganic particles can be secured while also sufficiently securing empty spaces formed between inorganic particles.

[0124] In one embodiment of the present invention, the organic-inorganic composite porous layer may have a structure in which the inorganic particles are filled and in contact with each other, and are bound together by the binder polymer, thereby forming interstitial volumes between the inorganic particles, and the interstitial volumes between the inorganic particles become empty spaces to form pores.

[0125] In one embodiment of the present invention, the lithium secondary battery comprises an electrolyte, and the electrolyte may comprise a non-aqueous solvent and a lithium salt. Additionally, an organic solid electrolyte or an inorganic solid electrolyte may be used as the electrolyte.

[0126] As the above-mentioned non-aqueous solvent, for example, non-protic organic solvents such as N-methyl-2-pyrrolidone, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfranc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxymethane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-ibidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ether, methyl propionate, ethyl propionate, etc. may be used.

[0127] The above lithium salt is a substance that is easily soluble in the above organic solvent, for example, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB 10 Cl 10 LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (CF3SO2)2NLi, lithium chloroborane, lithium lower aliphatic carboxylate, lithium 4-phenylborate, imide, etc. may be used.

[0128] In addition, for the purpose of improving charge / discharge characteristics, flame retardancy, etc., the electrolyte may be further enriched with, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. In some cases, to impart non-flammability, a halogen-containing solvent such as carbon tetrachloride or trifluoroethylene may be further enriched, and carbon dioxide gas may be further enriched to improve high-temperature storage characteristics.

[0129] The above organic solid electrolyte may be, for example, a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, agitation lysine, a polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, a polymer containing an ionic dissociator, etc.

[0130] As the above-mentioned inorganic solid electrolyte, for example, nitrides, halides, sulfates of Li such as Li3N, LiI, Li5NI2, Li3N-LiI-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li2SiS3, Li4SiO4, Li4SiO4-LiI-LiOH, Li3PO4-Li2S-SiS2, etc., may be used.

[0131] The above-mentioned electrolyte injection can be performed at an appropriate stage during the battery manufacturing process, depending on the manufacturing process and required physical properties of the final product. That is, it can be applied before battery assembly or at the final stage of battery assembly.

[0132] There are no specific restrictions on the external shape of the above lithium secondary battery, but it may be a cylindrical type using a can, a prismatic type, a pouch type, or a coin type.

[0133]

[0134] According to another aspect of the present invention,

[0135] A step of preparing a mixture by dry mixing and kneading the electrode active material and the first conductive material-first binder composite without a solvent;

[0136] A step of grinding the above mixture;

[0137] A step of manufacturing an electrode sheet by feeding the above-mentioned crushed product between a plurality of rolls and calendering it; and

[0138] A method for manufacturing an electrode according to one embodiment of the present invention is provided, comprising the step of laminating the electrode sheet on at least one surface of a current collector.

[0139]

[0140] First, a mixture is prepared by dry mixing and kneading the electrode active material and the first conductive material-first binder composite without a solvent.

[0141] According to one embodiment of the present invention, the first conductive material-first binder composite may be formed by dry-fusion of the first conductive material and the first binder such that the first conductive material is bonded to the surface of the first binder.

[0142] The above dry fusion is a dry mechanical composite technology that develops new materials by applying mechanical energy to multiple different material particles and causing a mechanochemical reaction. Recently, new materials can be developed by applying a type of mechanical energy to multiple different material particles, causing a reaction, and resulting in surface fusion between the multiple different material particles. Compared to other particle composite methods such as the wet method, this method has the special advantage of a simpler process and a significantly wider range of combinations.

[0143] According to one embodiment of the present invention, in the step of dry-fusion of the first conductive material and the first binder, the first conductive material is attached to the surface of the first binder, which is an activated nuclear particle, by applying mechanical action. After the first conductive material is attached to the surface of the first binder, the first conductive material is laminated and simultaneously the laminated first conductive material is compressed to form the first conductive material-first binder composite, wherein the bonding interface between the first conductive material and the first binder is rigid. At this time, the first conductive material and the first binder may be applied to the dry-fusion in the form of particles.

[0144] As a result, the first conductive material-first binder composite may have a structure in which a first conductive material layer is firmly formed on the surface of the first binder in a manner such as by laminating the first conductive material on the surface of the first binder, forming a groove on the surface of the first binder so that the first conductive material penetrates into it, or inserting the first conductive material into the pores on the surface of the first binder.

[0145] In addition, the dry fusion when forming the first conductive material-first binder composite can be carried out at a speed of 1,000 to 9,000 rpm, or 1,000 to 7,000 rpm, or 2,000 to 6,000 rpm for a time of 5 to 60 minutes, or 10 to 45 minutes. When the above speed and time conditions are satisfied, the dispersibility of the particles is improved, so that a surface protection layer containing a metal oxide can be uniformly formed on the surface of the electrode active material.

[0146] According to one embodiment of the present invention, the electrode active material and the first conductive material-first binder composite can be mixed by various methods provided that they are mixed dry without a solvent so that they are uniformly distributed. For example, the mixing can be performed by introducing the materials into a device such as a blender or a supermixer.

[0147] The step of preparing the above mixture may be carried out in one device for the mixing step and the kneading step, or in separate devices.

[0148] For example, a mixture can be prepared by performing mixing and kneading through a kneader, or a mixture can be prepared by performing a mixing step in advance before using the kneader and then passing the resulting product through the kneader. In this case, the mixing can be performed in the mixer at 3,000 rpm to 30,000 rpm for 10 seconds to 5 minutes, or at 5,000 rpm to 20,000 rpm for 10 seconds to 3 minutes to ensure uniformity.

[0149] According to one embodiment of the present invention, the step of preparing the mixture may include a step of mixing and kneading dry without a solvent, additionally including one or more of a second conductive material and a second binder in addition to the electrode active material and the first conductive material-first binder composite.

[0150] At this time, regarding the first conductive material, first binder, electrode active material, second conductive material, and second binder used, the foregoing provisions shall be applied.

[0151] According to one embodiment of the present invention, the process may be carried out at a temperature of 25 to 200°C or 50 to 150°C using the kneader, for 2 to 10 minutes at 10 to 100 rpm, or for 3 to 7 minutes at 10 to 30 rpm.

[0152] According to one embodiment of the present invention, when a second binder is included in the mixing step, a mixture having 100% solid content can be produced by combining or connecting the electrode active material, the first conductive material-first binder composite, or the second conductive material optionally included, as the second binder is fiberized in the kneading step.

[0153]

[0154] Afterwards, the above mixture is crushed.

[0155] Although the mixture obtained through the above mixing and kneading may be calendered immediately, in this case, the mixture may need to be pressed under high pressure and high temperature to be manufactured into a thin sheet or film. Consequently, problems may arise where the density of the sheet or film becomes too high or a uniform sheet cannot be obtained; therefore, the manufactured mixture may undergo the grinding step.

[0156] At this time, the grinding may be performed using a device such as a blender, a cutter mill, or a fine impact mill, although not limited thereto, and the grinding may be carried out at 5,000 rpm to 20,000 rpm for 10 seconds to 5 minutes, or at 10,000 rpm to 20,000 rpm for 10 seconds to 3 minutes.

[0157] Next, the crushed product is fed between a plurality of rolls and calendered to form an electrode sheet.

[0158] The calendering described above is a step of processing the crushed product into a sheet form, for example, by manufacturing it into a sheet form having an average thickness of 50 μm to 300 μm. The calendering described above may be performed, for example, by one or more pairs of rolls facing each other, and roll operation may be controlled to have a temperature of 25°C to 200°C and a rotational speed of 5 rpm to 20 rpm.

[0159] Afterwards, the above electrode sheet is laminated onto the current collector.

[0160] In the above lamination step, in order to form an electrode sheet on at least one surface of a current collector, the electrode sheet may be rolled and attached to the current collector to a predetermined thickness. The lamination may be performed by a lamination roll, and at this time, the lamination roll may be controlled to a temperature of 25°C to 200°C.

[0161] The present invention will be described in more detail below through examples, but the following examples are intended to illustrate the invention and the scope of the invention is not limited thereto.

[0162]

[0163] Example 1

[0164] (1) Preparation of the first conductive material-first binder composite

[0165] A first conductive material-first binder composite was prepared by preparing a first conductive material with a first conductive material attached to the surface of the first binder, using a first conductive material, multi-walled carbon nanotube (MWCNT) (manufacturer: LG Chem, product name: LUCAN BT-1003M) as the first conductive material and polypropylene (manufacturer: LG Chem, product name: H7918, weight-average molecular weight (MW): 60,000 g / mol) as the first binder in a weight ratio of 5:95, and processing it under conditions of 2,000 rpm and 30 minutes using a dry fusion facility (HOSOKAWAMICRON CORPORATION, Nobilta NOB-MINI).

[0166] At this time, the first binder had a composite viscosity of 18 Pa·s measured under conditions of 170°C and 0.1 Hz using an Advanced Rheometric Expansion System (ARES-G2), and a melt index of 1800 g / 10 min measured under conditions of 230°C and 2.16 kg according to ASTM D-1238.

[0167]

[0168] (2) Manufacturing of the electrode (anode)

[0169] As an electrode active material, lithium nickel-cobalt-manganese-aluminum oxide (NCMA, Li[Ni]) having an average particle size (D50) of 10㎛ 0.88 Co 0.07 Mn 0.04 ]Al 0.01 96 parts by weight of O2, 1 part by weight of the previously prepared first conductive material-first binder composite, 1.5 parts by weight of carbon black (manufacturer: Denka, product name: FX-35) as the second conductive material, and 1.5 parts by weight of polytetrafluoroethylene (Daikin, 601X) as the second binder were placed into a lab blender and mixed at 10,000 rpm for 1 minute. The temperature of the kneader was stabilized at 150°C, and the resulting mixture was placed into the kneader and kneaded at a speed of 25 rpm for 5 minutes under a cover pressure of 1.1 atmospheres to obtain a mixture. The mixture was placed into a blender and ground at 10,000 rpm for 15 seconds. Subsequently, the ground product was placed into a lab calender to manufacture an electrode sheet. The electrode sheet manufactured in this way was laminated onto an aluminum foil (16 μm) coated with a conductive primer layer in which carbon black and an acrylic binder were mixed in a weight ratio of 5:6, using a compression roll maintained at 150°C to manufacture an electrode. The total thickness of the electrode manufactured in this way was 90 μm, and the thickness of the active material layer formed on the current collector was 74 μm.

[0170]

[0171] Example 2

[0172] An electrode was manufactured in the same manner as in Example 1, except that a first conductive material-first binder composite having a first conductive material bonded to the surface of the first binder was prepared by preparing a first conductive material as a first conductive material, multi-walled carbon nanotubes (MWCNT) (manufacturer: LG Chem, product name: LUCAN BT-1003M) as a first conductive material and polypropylene (manufacturer: LG Chem, product name: H7918) as a first binder in a weight ratio of 10:90, and processing it under conditions of 2,000 rpm and 30 minutes using a dry fusion facility (HOSOKAWAMICRON CORPORATION, Nobilta NOB-MINI).

[0173] The total thickness of the electrode manufactured in this way was 90㎛, and the thickness of the active material layer formed on the current collector was 74㎛.

[0174] Figure 1 shows photographs of the first conductive material-first binder composite of Example 2 before and after preparation. Referring to Figure 1, the left side shows an optical and SEM photograph of polypropylene without the first conductive material, multi-walled carbon nanotubes, being composited, and the right side shows an optical and SEM photograph of the first conductive material-first binder composite in which the first conductive material, multi-walled carbon nanotubes, are coated on the surface of the first binder, polypropylene, and composited.

[0175]

[0176] Example 3

[0177] An electrode was manufactured in the same manner as in Example 1, except that a first conductive material-first binder composite having a first conductive material bonded to the surface of the first binder was prepared by preparing a first conductive material as a first conductive material, multi-walled carbon nanotubes (MWCNT) (manufacturer: LG Chem, product name: LUCAN BT-1003M) as a first conductive material and polypropylene (manufacturer: LG Chem, product name: H7918) as a first binder in a weight ratio of 15:85, and processing it under conditions of 2,000 rpm and 30 minutes using a dry fusion facility (HOSOKAWAMICRON CORPORATION, Nobilta NOB-MINI).

[0178] The total thickness of the electrode manufactured in this way was 90㎛, and the thickness of the active material layer formed on the current collector was 74㎛.

[0179]

[0180] Comparative Example 1

[0181] As an electrode active material, lithium nickel-cobalt-manganese-aluminum oxide (NCMA, Li[Ni]) having an average particle size (D50) of 10㎛ 0.88 Co 0.07 Mn 0.04 ]Al 0.0196 parts by weight of O2, 1 part by weight of polypropylene (manufacturer: LG Chem, product name: H7918) as a first binder, 1.5 parts by weight of carbon black as a conductive material, and 1.5 parts by weight of polytetrafluoroethylene (Daikin, 601X) as a second binder were added to a lab blender and mixed at 10,000 rpm for 1 minute. The temperature of the kneader was stabilized at 150°C, and the resulting mixture was placed into the kneader and kneaded at a speed of 25 rpm for 5 minutes under a cover pressure of 1.1 atmospheres to obtain a mixture. The mixture was then added to a blender and ground at 10,000 rpm for 15 seconds. Subsequently, the ground product was fed into a lab calender to manufacture an electrode sheet. The electrode sheet manufactured in this way was laminated onto an aluminum foil (16㎛) coated with a conductive primer layer in which carbon black and an acrylic binder were mixed in a weight ratio of 5:6, using a compression roll maintained at 150℃ to manufacture the electrode.

[0182] The total thickness of the electrode manufactured in this way was 90㎛, and the thickness of the active material layer formed on the current collector was 74㎛.

[0183]

[0184] Evaluation results

[0185] (1) Evaluation of the first conductive material-first binder composite

[0186] [Flowability Index Evaluation]

[0187] The Flow Function (FF) values ​​of the first conductive material-first binder composites prepared in Examples 1, 2, and 3 were measured using a powder rheometer, and the results are shown in Table 1.

[0188] The above powder rheometer used was the FT4 powder rheometer from Micromeritics, a general-purpose powder rheometer, and the value of the powder characteristic was obtained as the arithmetic mean of three shear cell tests performed at a pressure of 10 kPa.

[0189]

[0190] [Powder Resistance Evaluation]

[0191] The powder resistance of the first conductive material-first binder composite prepared in Examples 1, 2, and 3, carbon black (manufacturer: Denka, product name: FX-35), and multi-walled carbon nanotube (MWCNT) (manufacturer: LG Chem, product name: LUCAN BT-1003M) was measured using a powder resistor, and the results are shown in Figure 2.

[0192] The HPRM-FA2 from HANTECH was used as the powder resistor, and a measured amount of powder was placed into the measuring cell of the powder resistor. The powder was compressed by increasing the force from 400gf to 2000gf in increments of 400gf using a punch, and the density and powder resistance corresponding to each force were measured.

[0193] Referring to Figure 2, it can be seen that the conductivity of a binder material with very high resistance is improved to secure a resistance level equivalent to that of carbon black, a point-type conductive material. Specifically, when the binder is used alone, the resistance is close to infinity, but it can be confirmed that an electrical resistance level equivalent to that of carbon black is secured through the composite with a conductive material.

[0194]

[0195] First binder (used in Examples 1 to 3) Example 1 Example 2 Example 3 Flow Function (FF) 1.78 2.33 2.91 3.11

[0196] Referring to Table 1, the first conductive material-first binder composite of Examples 1 to 3, obtained by combining multi-walled carbon nanotubes as the first conductive material and polypropylene as the first binder, showed significantly increased flowability compared to the first binder alone, and it can be confirmed that the dispersibility of the conductive material in the electrode equipped with the first conductive material-first binder composite of Examples 1 to 3 was improved from the improved battery characteristics and resistance characteristics described later.

[0197] (2) Evaluation of electrodes and batteries

[0198] [thickness]

[0199] The total thickness of the electrode (anode) and the thickness of the active material layer of Examples 1 to 3 and Comparative Example 1 prepared above were measured using a thickness gauge (Mitutoyo, VL-50S-B).

[0200]

[0201] [Battery Capacity Evaluation]

[0202] The initial capacity of a secondary battery containing the electrode (anode) of Examples 1 to 3 and Comparative Example 1 prepared above was measured using the following method, and the results are shown in Table 2 below.

[0203] First, a secondary battery containing the electrode (anode) of Examples 1 to 3 and Comparative Example 1 was manufactured by the following method.

[0204]

[0205] Preparation of Electrolyte

[0206] An electrolyte containing 1M LiPF6 of 2wt% vinylene carbonate (VC) was prepared in a solvent of ethylene carbonate (EC) : dimethyl carbonate (DMC) : diethyl carbonate (DEC) = 1 : 2 : 1 (volume ratio).

[0207]

[0208] Manufacturing of secondary batteries

[0209] A positive electrode prepared in Examples 1 to 3 and Comparative Example 1 was each punched to a size of 14 pi, and a negative electrode made of Li metal (Honjo, 500 μm) was punched to a size of 15 pi. Then, a polyethylene separator was placed between them and embedded in an aluminum pouch, and the prepared electrolyte was injected and sealed to manufacture a coin-type secondary battery.

[0210]

[0211] Evaluation of Initial Capacity

[0212] The above-mentioned secondary batteries were charged and discharged (3.0V) three times in a 0.1C CC / CV mode with an upper voltage limit of 4.25V at room temperature of 25°C, and the average value of the three capacities is shown in Table 2.

[0213]

[0214] <2.5C rate capacity evaluation>

[0215] The above-mentioned secondary battery cells were charged and discharged (3.0V) three times in a 2.5C CC / CV mode with an upper voltage limit of 4.25V at room temperature of 25°C, and the average value of the three capacities is shown in Table 2.

[0216]

[0217] [Volume Resistance]

[0218] The electrodes (anodes) prepared in Examples 1 to 3 and Comparative Example 1 are 50 x 50 mm 2 A sample of the size was prepared, the prepared sample was placed in a Multi-probe Tester (HIOKI, RM2610) at room temperature of 25 degrees Celsius, and the volume resistivity (Ω·cm) of the electrode was measured.

[0219]

[0220] [Interfacial Resistance]

[0221] The electrodes (anodes) prepared in Examples 1 to 3 and Comparative Example 1 are 50 x 50 mm 2Prepare a sample of the size, place the prepared electrode sample into a Multi-probe Tester (HIOKI, RM2610) at room temperature of 25 degrees Celsius, and the interfacial resistance (Ω·cm) of the electrode 2 ) measured

[0222]

[0223] Example 1 Example 2 Example 3 Comparative Example 1 Initial Capacity (mAh / g) 205.2 205.4 205.5 205.0 2.5 C Rate Capacity (mAh / g) 70.9 96.7 98.8 65.8 Volume Resistance (ohm-cm) 5138 3762 Interface Resistance (ohm-cm) 2 )0.120.090.090.15

[0224] As described above, although the present invention has been explained by limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

Claims

1. An electrode current collector; and an electrode active material layer formed on at least one surface of the electrode current collector, and The above electrode active material layer comprises an electrode active material and a first conductive material-first binder composite, and The above first conductive material includes carbon nanotubes, and An electrode characterized in that the first binder has a composite viscosity of 1,500 Pa·s or less at 170°C and 0.1 Hz.

2. In Paragraph 1, An electrode characterized in that the first binder has a composite viscosity of 0.01 Pa·s to 1,500 Pa·s at 170°C and 0.1 Hz.

3. In Paragraph 1, An electrode characterized in that the first conductive material-first binder composite comprises a first binder and a first conductive material bonded to the surface of the first binder.

4. In Paragraph 1, An electrode characterized in that the first binder comprises a polyolefin-based polymer.

5. In Paragraph 1, An electrode characterized in that the first binder comprises polyethylene, polypropylene, polybutylene, polypentene, or two or more of these.

6. In Paragraph 1, An electrode characterized by the weight-average molecular weight of the first binder being 5,000 g / mol to 200,000 g / mol.

7. In Paragraph 1, An electrode characterized in that the weight ratio of the first conductive material and the first binder in the first conductive material-first binder composite is 1:99 to 30:

70.

8. In Paragraph 1, An electrode characterized in that the electrode active material layer further comprises one or more of a second conductive material and a second binder.

9. In Paragraph 8, An electrode characterized in that the second binder comprises polytetrafluoroethylene.

10. In Paragraph 8, An electrode characterized in that the weight ratio of the first binder and the second binder is 10:90 to 90:

10.

11. In Paragraph 1, An electrode characterized in that the electrode active material layer comprises 90 to 80 parts by weight of an electrode active material and 3 to 20 parts by weight of a first conductive material-first binder composite.

12. In Paragraph 8, An electrode characterized in that the electrode active material layer comprises 90 to 80 parts by weight of an electrode active material, 0.5 to 10 parts by weight of a first conductive material-first binder composite, 0.5 to 5 parts by weight of a second binder, and 0.5 to 5 parts by weight of a second conductive material.

13. A lithium secondary battery comprising: a positive electrode; a negative electrode; a separator disposed between the positive electrode and the negative electrode; and an electrolyte, wherein A lithium secondary battery characterized in that at least one of the above positive and negative electrodes is an electrode according to any one of claims 1 to 12.

14. A step of preparing a mixture by dry mixing and kneading the electrode active material and the first conductive material-first binder composite without a solvent; A step of grinding the above mixture; A step of manufacturing an electrode sheet by feeding the above-mentioned crushed product between a plurality of rolls and calendering it; and A method for manufacturing an electrode of claim 1, comprising the step of laminating the electrode sheet on at least one surface of a current collector.

15. In Paragraph 14, The above first conductive material-first binder composite A method for manufacturing an electrode characterized by forming a first conductive material and a first binder by dry fusing them so that the first conductive material is bonded to the surface of the first binder.

16. In Paragraph 15, A method for manufacturing an electrode characterized by performing the above dry fusion at a speed of 1,000 to 9,000 rpm for a period of 5 to 60 minutes.

17. In Paragraph 14, A method for manufacturing an electrode, characterized in that the step of preparing the above mixture includes a step of mixing and kneading dryly without a solvent, additionally including one or more of a second conductive material and a second binder in addition to the electrode active material and the first conductive material-first binder composite.

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