WO2019160391A1 - Cathode et batterie secondaire la comprenant - Google Patents

Cathode et batterie secondaire la comprenant Download PDF

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Publication number
WO2019160391A1
WO2019160391A1 PCT/KR2019/001960 KR2019001960W WO2019160391A1 WO 2019160391 A1 WO2019160391 A1 WO 2019160391A1 KR 2019001960 W KR2019001960 W KR 2019001960W WO 2019160391 A1 WO2019160391 A1 WO 2019160391A1
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Prior art keywords
positive electrode
active material
material layer
electrode active
carbon nanotubes
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PCT/KR2019/001960
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English (en)
Korean (ko)
Inventor
백주열
임준묵
이창주
오일근
김제영
최상훈
Original Assignee
주식회사 엘지화학
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Priority claimed from KR1020190018735A external-priority patent/KR102254265B1/ko
Application filed by 주식회사 엘지화학 filed Critical 주식회사 엘지화학
Priority to EP19754898.5A priority Critical patent/EP3716365A4/fr
Priority to US16/959,301 priority patent/US20200373559A1/en
Priority to CN201980007105.0A priority patent/CN111542950A/zh
Priority to JP2020535078A priority patent/JP7055476B2/ja
Publication of WO2019160391A1 publication Critical patent/WO2019160391A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a positive electrode and a secondary battery including the same satisfying an optimum relationship between a specific binder content and a specific carbon nanotube content.
  • the lithium secondary battery includes a positive electrode including a positive electrode active material capable of inserting / desorbing lithium ions, a negative electrode containing a negative electrode active material capable of inserting / removing lithium ions, and an electrode having a microporous separator interposed between the positive electrode and the negative electrode. It refers to a battery containing a nonaqueous electrolyte containing lithium ions in the assembly.
  • the positive electrode and / or the negative electrode may include a positive electrode active material layer containing a conductive material.
  • a positive electrode active material layer containing a conductive material Conventionally, viscous conductive materials, such as carbon black, were mainly used.
  • the capacity of the battery decreases while the amount of the positive electrode active material or the negative electrode active material is relatively reduced, or the adhesive force decreases while the positive electrode binder or the negative electrode binder is reduced.
  • the conductivity of the positive electrode active material itself is a low level, the problem appears more.
  • the carbon nanotubes have a relatively longer length than the particulate conductive material, the carbon nanotubes may improve the conductivity even with a small amount, and also improve the bonding strength of the positive electrode active material layers.
  • the positive electrode active material layer may include a binder.
  • the binder generally does not contribute to improving the conductivity of the positive electrode active material layer. Accordingly, even when carbon nanotubes are used, there is a limit in improving the conductivity by using them in combination with a binder.
  • a current collector and a positive electrode active material layer disposed on the current collector includes a positive electrode active material, carbon nanotubes, and a binder
  • the binder is a weight average molecular weight comprises at 720,000g / mol to 980,000g / mol of poly vinylidene fluoride and, BET specific surface area of the carbon nanotube is 140m 2 / g to 195m 2 / g, there is provided a positive electrode satisfies the following formula 1 .
  • B is the content (wt%) of the polyvinylidene fluoride in the positive electrode active material layer
  • A is the content (wt%) of the carbon nanotubes in the positive electrode active material layer.
  • a secondary battery including the positive electrode is provided.
  • the present invention by adjusting the BET specific surface area of the carbon nanotubes, the content ratio of the polyvinylidene fluoride and the carbon nanotubes, the weight average molecular weight of the polyvinylidene fluoride, to improve the conductivity and anode adhesion of the positive electrode
  • excessive increase and excessive decrease of the positive electrode slurry can be suppressed. Accordingly, there is an advantage in terms of processability and manufacturing cost in manufacturing the positive electrode, easy application of the positive electrode slurry, and the positive electrode active material layer may be uniformly formed.
  • the output of the battery and the service life at high temperatures can be further improved.
  • An anode according to an embodiment of the present invention.
  • B is the content (wt%) of the polyvinylidene fluoride in the positive electrode active material layer
  • A is the content (wt%) of the carbon nanotubes in the positive electrode active material layer.
  • the current collector may be any conductive material without causing chemical change in the battery, and is not particularly limited.
  • the current collector may be copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or a surface treated with carbon, nickel, titanium, silver, or the like on the surface of aluminum or stainless steel.
  • a transition metal that adsorbs carbon such as copper and nickel can be used as the current collector.
  • the positive electrode active material layer may be disposed on the current collector.
  • the positive electrode active material layer may be disposed on one surface or both surfaces of the current collector.
  • the cathode active material layer may include a cathode active material, carbon nanotubes, and a binder.
  • the cathode active material layer may be composed of a cathode active material, carbon nanotubes, and a binder.
  • the positive electrode active material has a high energy density, and enables a battery of high capacity.
  • the cathode active material has high energy density and excellent safety.
  • the average particle diameter (D 50 ) of the cathode active material may be 3 ⁇ m to 20 ⁇ m, specifically 6 ⁇ m to 18 ⁇ m, and more specifically 9 ⁇ m to 16 ⁇ m.
  • the average particle diameter D 50 may be defined as a particle size corresponding to 50% of the volume cumulative amount in the particle size distribution curve of the particles.
  • the average particle diameter D 50 may be measured using, for example, a laser diffraction method. In general, the laser diffraction method can measure the particle diameter of several mm from the submicron region, and high reproducibility and high resolution can be obtained.
  • the cathode active material may be 95.6% by weight to 99.0% by weight in the cathode active material layer, specifically, may be 97.0% by weight to 98.0% by weight.
  • the positive electrode adhesion and the conductivity of the positive electrode can be improved at the same time.
  • Carbon nanotubes in the present invention may serve as a cathode conductive material.
  • the cathode active material layer may include only carbon nanotubes as the cathode conductive material.
  • the positive electrode active material layer includes a particulate conductive material such as acetylene black or a plate conductive material in addition to carbon nanotubes, the conductivity of the positive electrode may be lower than that of the positive electrode of the present invention.
  • the carbon nanotubes may be bundled carbon nanotubes.
  • the bundled carbon nanotubes may include a plurality of carbon nanotube units.
  • the term 'bundle type' herein refers to a bundle in which a plurality of carbon nanotube units are arranged or intertwined side by side in substantially the same orientation in the longitudinal axis of the carbon nanotube unit unless otherwise stated. It refers to a secondary shape in the form of a bundle or rope.
  • the carbon nanotube unit has a graphite sheet having a nano size diameter cylinder shape, and has a sp 2 bonding structure. In this case, the graphite surface may exhibit characteristics of a conductor or a semiconductor depending on the angle and structure of the surface.
  • Carbon nanotube units are single-walled carbon nanotube (SWCNT) units, double-walled carbon nanotube (DWCNT) units and multi-walled carbon nanotubes (MWCNT) multi-walledcarbon nanotube) monomers.
  • the carbon nanotube unit may be a multi-walled carbon nanotube unit.
  • the multi-walled carbon nanotube unit has a lower energy required for dispersion than the single-walled carbon nanotube unit and the double-walled carbon nanotube unit, and is preferable in that it has a level of dispersion conditions that can be easily adjusted.
  • the average diameter of the carbon nanotube unit may be 1nm to 30nm, specifically 3nm to 26nm, may be more specifically 5nm to 22nm.
  • the average diameter can be measured by TEM or SEM.
  • the BET specific surface area of the carbon nanotubes may be 140m 2 / g to 195m 2 / g, specifically 145m 2 / g to 195m 2 / g, more specifically 160m 2 / g to 190m 2 / g day Can be.
  • the BET specific surface area of the carbon nanotube is less than 140 m 2 / g, since the viscosity of the positive electrode slurry is too low during the production of the positive electrode, the positive electrode slurry coating and drying processability is lowered and the manufacturing cost is excessively increased.
  • due to the reduction in the BET specific surface area the conductive path is reduced, and the conductivity of the anode is greatly reduced.
  • the BET specific surface area of the carbon nanotube is more than 195m 2 / g, the viscosity of the positive electrode slurry is too high, it is very difficult to apply the positive electrode slurry to the current collector, the positive electrode formed because the positive electrode slurry can not be uniformly applied The active material layer is not uniform.
  • the BET specific surface area can be measured by nitrogen adsorption BET method.
  • the binder may include poly vinylidene fluoride (PVdF).
  • PVdF poly vinylidene fluoride
  • the weight average molecular weight of the polyvinylidene fluoride may be 720,000g / mol to 980,000g / mol, specifically 750,000g / mol to 950,000g / mol, more specifically 800,000g / mol to 920,000g / may be mol.
  • the weight average molecular weight is less than 720,000g / mol, even if the formula 1 to be described later to meet the viscosity of the positive electrode slurry formed during the production of the positive electrode is too low, the coating of the positive electrode slurry is difficult, the processability during drying is too low, the manufacturing cost is excessive Will rise.
  • the positive electrode adhesive force is excessively reduced to detach the positive electrode active material.
  • the weight average molecular weight is more than 980,000g / mol
  • the positive electrode and the battery resistance is excessively increased.
  • the viscosity of the positive electrode slurry is excessively increased, for example, is excessively increased to 50,000 cps or more at room temperature, the application of the positive electrode slurry is difficult, and the positive electrode active material layer formed is not uniform, and battery performance may be reduced.
  • the weight average molecular weight of the polyvinylidene fluoride simultaneously satisfies the improvement of processability and manufacturing cost, uniformity of the positive electrode active material layer, improvement of the conductivity of the positive electrode, and improvement of the positive electrode adhesion, within a limited composition, considering the amount of the carbon nanotubes used. Is the most optimal range.
  • the binder may further include a non-fluorine binder.
  • the non-fluorine-based binder may be at least one of nitrile butadiene rubber (NBR) and hydrogenated nitrile butadiene rubber (H-NBR), and specifically, may be hydrogenated nitrile butadiene rubber.
  • the weight ratio of the polyvinylidene fluoride and the non-fluorine-based binder may be 23: 1 to 1: 1, specifically 20: 1 to 3: 1. When satisfying the above range, there is an effect of improving the positive electrode adhesion and dispersion of carbon nanotubes.
  • the positive electrode of the present invention may satisfy the following Equation 1.
  • B is the content (wt%) of the polyvinylidene fluoride in the positive electrode active material layer
  • A is the content (wt%) of the carbon nanotubes in the positive electrode active material layer.
  • the B / A is less than 1.3, the positive electrode adhesion is too weak to cause the detachment of the positive electrode active material during the production of the positive electrode.
  • the viscosity of the positive electrode slurry is excessively increased, application of the positive electrode slurry is difficult, and the positive electrode active material layer formed is not uniform, and battery performance may be reduced.
  • the B / A is more than 3.4, the positive electrode adhesion is excellent, but the powder resistance is too high, the battery resistance is excessively increased. As a result, the output characteristics of the battery are greatly reduced.
  • the viscosity of the positive electrode slurry formed during the production of the positive electrode is too low, coating of the positive electrode slurry is difficult, the processability during drying is excessively lowered, and the manufacturing cost is excessively increased.
  • the anode may specifically satisfy the following Equation 2.
  • the powder resistance and the anode adhesion may be further improved. This is because the viscosity of the positive electrode slurry is somewhat increased while not decreasing the uniformity of the positive electrode active material layer, and the migration of the binder in the positive electrode slurry is suppressed. Accordingly, the anode adhesion is improved, and since the binder is not applied unevenly, the conductivity across the anode can be further improved.
  • Secondary battery according to another embodiment of the present invention is a positive electrode; cathode; A separator interposed between the anode and the cathode; And it may include an electrolyte, the positive electrode is the same as the positive electrode of the above-described embodiment. The description of the anode is omitted.
  • the negative electrode may include a negative electrode current collector and a negative electrode active material layer disposed on one or both surfaces of the negative electrode current collector.
  • the negative electrode current collector may be any one having conductivity without causing chemical change in the battery, and is not particularly limited.
  • the negative electrode current collector may be copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or a surface treated with carbon, nickel, titanium, silver, or the like on the surface of aluminum or stainless steel.
  • a transition metal that adsorbs carbon such as copper and nickel can be used as the current collector.
  • the negative electrode active material layer may include a negative electrode active material, a negative electrode conductive material, and a negative electrode binder.
  • the negative electrode active material may be graphite-based active material particles or silicon-based active material particles.
  • the graphite-based active material particles may be used at least one selected from the group consisting of artificial graphite, natural graphite, graphitized carbon fibers and graphitized mesocarbon microbeads, and in particular, when using artificial graphite, the rate characteristics may be improved. .
  • the silicon-based active material particles are Si, SiO x (0 ⁇ x ⁇ 2), Si-C composite and Si-Y alloy (where Y is an alkali metal, alkaline earth metal, transition metal, group 13 element, group 14 element, rare earth element And it is an element selected from the group consisting of a combination thereof) may be used one or more selected from the group consisting of, in particular, when using Si can derive a high capacity of the battery.
  • the negative electrode binder is polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (polyvinylidene fluoride), polyacrylonitrile (polyacrylonitrile), polymethylmethacrylate (polymethylmethacrylate), Polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), Sulfonated EPDM, styrene butadiene rubber (SBR), fluorine rubber, poly acrylic acid (poly acrylic acid) and may include at least one selected from the group consisting of substances substituted with hydrogen, such as Li, Na or Ca, And also various copolymers thereof.
  • PVDF-co-HFP polyvinyliden
  • the negative electrode conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, farnes black, lamp black and thermal black; Conductive fibers such as carbon fibers and metal fibers; Conductive tubes such as carbon nanotubes; Metal powders such as fluorocarbon, aluminum and nickel powders; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.
  • graphite such as natural graphite and artificial graphite
  • Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, farnes black, lamp black and thermal black
  • Conductive fibers such as carbon fibers and metal fibers
  • Conductive tubes such as carbon nanotubes
  • Metal powders such as fluorocarbon, aluminum and nickel powders
  • the separator is to separate the negative electrode and the positive electrode and to provide a passage for the movement of lithium ions, and can be used without any particular limitation as long as the separator is used as a separator in a secondary battery. It is desirable to be excellent.
  • a porous polymer film for example, a porous polymer film made of a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer or the like Laminate structures of two or more layers may be used.
  • porous nonwoven fabrics such as nonwoven fabrics made of high melting point glass fibers, polyethylene terephthalate fibers and the like may be used.
  • a coated separator including a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength, and may be optionally used as a single layer or a multilayer structure.
  • the electrolyte may include an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, and the like, which can be used in manufacturing a lithium secondary battery, but are not limited thereto.
  • the electrolyte may include a non-aqueous organic solvent and a metal salt.
  • non-aqueous organic solvent for example, N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butylo lactone, 1,2-dime Methoxy ethane, tetrahydroxy franc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolon, formamide, dimethylformamide, dioxoron, acetonitrile, nitromethane, methyl formate, Methyl acetate, phosphate triester, trimethoxy methane, dioxorone derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, pyrion
  • An aprotic organic solvent such as methyl acid or ethyl
  • ethylene carbonate and propylene carbonate which are cyclic carbonates among the carbonate-based organic solvents, may be preferably used as high-viscosity organic solvents because they have high dielectric constants to dissociate lithium salts well.
  • an electrolyte having a high electrical conductivity can be made, and thus it can be more preferably used.
  • the metal salt may be a lithium salt
  • the lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for example, is in the lithium salt anion F -, Cl -, I - , NO 3 -, N (CN ) 2 -, BF 4 -, ClO 4 -, PF 6 -, (CF 3) 2 PF 4 -, (CF 3) 3 PF 3 -, (CF 3) 4 PF 2 -, (CF 3) 5 PF - , (CF 3) 6 P - , CF 3 SO 3 -, CF 3 CF 2 SO 3 -, (CF 3 SO 2) 2 N -, (FSO 2) 2 N -, CF 3 CF 2 (CF 3) 2 CO -, (CF 3 SO 2 ) 2 CH -, (SF 5) 3 C -, (CF 3 SO 2) 3 C -, CF 3 (CF 2) 7 SO 3 -, CF 3 CO 2 -, CH 3 CO 2 -
  • the electrolyte includes, for example, haloalkylene carbonate-based compounds such as difluoro ethylene carbonate, pyridine, tri, etc. for the purpose of improving battery life characteristics, reducing battery capacity, and improving discharge capacity of the battery.
  • haloalkylene carbonate-based compounds such as difluoro ethylene carbonate, pyridine, tri, etc.
  • Ethyl phosphite triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphate triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N, N-substituted imida
  • One or more additives such as zolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxy ethanol or aluminum trichloride may be included.
  • a battery module including the secondary battery as a unit cell and a battery pack including the same are provided. Since the battery module and the battery pack include the secondary battery having high capacity, high rate characteristics, and cycle characteristics, a medium-large device selected from the group consisting of an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, and a power storage system It can be used as a power source.
  • Li (Ni 0.6 Mn 0.2 Co 0.2 ) O 2 having an average particle diameter (D 50 ) of 12 ⁇ m was used, and as a conductive material, a bundle type carbon nanotube (specific surface area) composed of carbon nanotube units (multi-walls) This 185 m 2 / g) was used, and the average diameter of the carbon nanotube unit was 12 nm.
  • a conductive material dispersion including the multi-walled carbon nanotubes, hydrogenated nitrile butadiene rubber (H-NBR), and N-methylpyrrolidone (NMP, N-methylpyrrolidone) as a dispersion medium was prepared. Thereafter, the positive electrode active material, PVdF having a weight average molecular weight of 880,000 g / mol, the conductive material dispersion, and NMP were mixed to have a solid content of 72%, and a weight ratio of the positive electrode active material, carbon nanotubes, PVdF, and H-NBR was 97.5.
  • a positive electrode slurry was prepared which was: 0.7: 1.66: 0.14.
  • the carbon nanotubes, PVdF and H-NBR content, the BET specific surface area of the carbon nanotubes, and the weight average molecular weight of PVdF was changed in the same manner as in Example 1 except that The positive electrode slurries of Examples 2 to 4 and Comparative Examples 1 to 7 were prepared.
  • the content of each of the cathode active material, carbon nanotubes, PVdF, and H-NBR is based on the total weight of the cathode active material layer.
  • the viscosity of the positive electrode slurry of Examples 1 to 4 and Comparative Examples 1 to 7 was measured at 25 ° C. using a Brookfield Type B viscometer. Specifically, the viscosity after rotation for 1 minute at rotor number 64 and the rotation speed 12 rpm was measured, and is shown in Table 2.
  • Each of the positive electrode slurries of Examples 1 to 4 and Comparative Examples 1 to 7 was vacuum dried at a temperature of 130 ° C. for 3 hours and then ground to prepare a powder. Thereafter, using Loresta GP equipment of Mitsubishi Chem Analytic, pellets were prepared under a load of 9.8 MPa under 25 ° C. and 50% relative humidity. Then, after measuring the powder resistance by the 4-probe method, it is shown in Table 2.
  • a positive electrode was prepared. Specifically, the positive electrode slurry was applied to a positive electrode current collector (Al) having a thickness of 20 ⁇ m, and dried in a vacuum oven at 130 ° C. for 6 hours. Thereafter, the current collector to which the positive electrode slurry was applied was sandwiched between rolls heated at 60 ° C. and rolled at a pressure of 10 MPa to obtain a final thickness (current collector + active material layer) of 95 ⁇ m, and the loading amount of the positive electrode active material layer was 680 mg / A positive electrode having 25 cm 2 was prepared.
  • Al positive electrode current collector
  • the positive electrode was punched into 20 mm x 150 mm and fixed to the center of the 25 mm x 75 mm slide glass using a tape, and then peeled off the current collector using UTM to measure the peel strength of 90 degrees. Five or more peel strengths were measured for each positive electrode, and then the average value was expressed as positive electrode adhesion. The measurement results are shown in Table 2.
  • Comparative Example 3 and Comparative Example 7 having a BET specific surface area of 280 m 2 / g, 220 m 2 / g higher than the examples, the positive electrode slurry viscosity is too high.
  • Comparative Example 4 which has a BET specific surface area of 120 m 2 / g, which is lower than those of Examples, it can be seen that the anode slurry viscosity is too low. Therefore, since the positive electrode slurry viscosity can satisfy the desired level only when the BET specific surface area of an appropriate level is satisfied, coating and drying processability at the time of manufacturing a positive electrode can be improved, manufacturing cost can be reduced, and a positive electrode active material layer can be uniformly formed. Can be. In addition, since the powder resistance of both Comparative Example 3 and Comparative Example 4 is too high, it can be seen that the conductivity of the positive electrode is secured only when the BET specific surface area satisfies an appropriate level.
  • Comparative Example 5 in which the weight average molecular weight of polyvinylidene fluoride is 1,200,000 g / mol and higher than 980,000 g / mol, it can be seen that both the powder resistance and the positive electrode slurry viscosity are very high.
  • Comparative Example 6 in which the weight average molecular weight of polyvinylidene fluoride is 500,000 g / mol, which is lower than 720,000 g / mol, the powder resistance is good, but the viscosity of the positive electrode slurry is too low, so that coating and drying processability are extremely high when manufacturing the positive electrode. It is hindered and manufacturing costs are bound to rise. In addition, since the positive electrode adhesion is too low, desorption of the positive electrode active material is expected.

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Abstract

La présente invention concerne une cathode comprenant un collecteur de courant et une couche de matériau actif de cathode disposée sur le collecteur de courant, la couche de matériau actif de cathode comprenant un matériau actif de cathode, un nanotube de carbone et un liant, le liant comprenant du fluorure de polyvinylidène ayant un poids moléculaire moyen en poids de 720000 g/mol à 980000 g/mol, le nanotube de carbone ayant une surface spécifique BET de 140m2/g à 195m2/g, et satisfaisant la formule suivante 1. [Formule 1] 1,3 ≤ B/A ≤ 3,4 où B est une teneur (% en poids) du fluorure de polyvinylidène dans la couche de matériau actif de cathode et A est une teneur (% en poids) du nanotube de carbone dans la couche de matériau actif de cathode.
PCT/KR2019/001960 2018-02-19 2019-02-19 Cathode et batterie secondaire la comprenant WO2019160391A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP19754898.5A EP3716365A4 (fr) 2018-02-19 2019-02-19 Cathode et batterie secondaire la comprenant
US16/959,301 US20200373559A1 (en) 2018-02-19 2019-02-19 Positive Electrode and Secondary Battery Including the Positive Electrode
CN201980007105.0A CN111542950A (zh) 2018-02-19 2019-02-19 正极和包括所述正极的二次电池
JP2020535078A JP7055476B2 (ja) 2018-02-19 2019-02-19 正極及び該正極を含む二次電池

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR20180019487 2018-02-19
KR10-2018-0019487 2018-02-19
KR1020190018735A KR102254265B1 (ko) 2018-02-19 2019-02-18 양극 및 상기 양극을 포함하는 이차 전지
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CN111106302A (zh) * 2019-11-25 2020-05-05 深圳市卓能新能源股份有限公司 一种圆柱型锂离子电池及其制备方法
CN116387634A (zh) * 2023-06-05 2023-07-04 宁德时代新能源科技股份有限公司 电极组件、电池单体、电池和用电设备

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CN111106302A (zh) * 2019-11-25 2020-05-05 深圳市卓能新能源股份有限公司 一种圆柱型锂离子电池及其制备方法
CN116387634A (zh) * 2023-06-05 2023-07-04 宁德时代新能源科技股份有限公司 电极组件、电池单体、电池和用电设备
CN116387634B (zh) * 2023-06-05 2024-01-26 宁德时代新能源科技股份有限公司 电极组件、电池单体、电池和用电设备

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