WO2016032223A1 - Matériau actif d'électrode positive revêtu en surface, son procédé de préparation, et batterie rechargeable au lithium le comprenant - Google Patents

Matériau actif d'électrode positive revêtu en surface, son procédé de préparation, et batterie rechargeable au lithium le comprenant Download PDF

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WO2016032223A1
WO2016032223A1 PCT/KR2015/008915 KR2015008915W WO2016032223A1 WO 2016032223 A1 WO2016032223 A1 WO 2016032223A1 KR 2015008915 W KR2015008915 W KR 2015008915W WO 2016032223 A1 WO2016032223 A1 WO 2016032223A1
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active material
positive electrode
electrode active
carbon black
coated
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PCT/KR2015/008915
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English (en)
Korean (ko)
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장욱
이상영
조승범
안준성
박장훈
김주명
Original Assignee
주식회사 엘지화학
국립대학법인 울산과학기술대학교 산학협력단
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Priority claimed from KR1020150117752A external-priority patent/KR101714892B1/ko
Application filed by 주식회사 엘지화학, 국립대학법인 울산과학기술대학교 산학협력단 filed Critical 주식회사 엘지화학
Priority to EP15835187.4A priority Critical patent/EP3188290B1/fr
Priority to CN201580030667.9A priority patent/CN106663799B/zh
Priority to US15/039,266 priority patent/US10476082B2/en
Publication of WO2016032223A1 publication Critical patent/WO2016032223A1/fr

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    • 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
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • 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
    • H01M4/36—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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • 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
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • 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
    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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 surface-coated positive electrode active material, a method of manufacturing the same, and a lithium secondary battery including the same. More specifically, the present invention relates to a cathode active material surface-coated with a nano-film including polyimide (PI) and carbon black, a method of manufacturing the same, and a lithium secondary battery including the same.
  • PI polyimide
  • Lithium secondary batteries have been widely used as power sources for portable devices since they emerged in 1991 as small, light and large capacity batteries. Recently, with the rapid development of electronics, telecommunications, and computer industry, camcorders, mobile phones, notebook PCs, etc. have emerged, and they are developing remarkably, and the demand for lithium secondary battery as a power source to drive these portable electronic information communication devices increases day by day. Doing.
  • Lithium secondary batteries have a problem in that their lifespan drops rapidly as they are repeatedly charged and discharged.
  • the surfaces of these cathode active materials are Al 2 O 3 , ZrO 2 , and AlPO 4. It is generally known that oxides such as these can be coated on the surface of the positive electrode active material. It is also established that the coating layer improves the safety characteristics of the positive electrode active material.
  • the oxide coating layer is finely dispersed in the form of nano-sized particles rather than entirely covering the surface of the positive electrode active material.
  • the surface modification effect of the positive electrode active material by the oxide coating layer was limited to be limited.
  • the oxide coating layer is a kind of ion insulating layer that is difficult to move lithium ions, and may cause a decrease in ion conductivity.
  • the present inventors are studying a positive electrode active material which is excellent in safety and can exhibit excellent life characteristics even under high voltage conditions, the present inventors include polyimide and carbon black having a specific iodine number and oil absorption number on the surface of the positive electrode active material.
  • the surface-coated positive electrode active material prepared by forming a nano-film can effectively suppress side reactions between the positive electrode active material and the electrolyte due to the nano-film, thereby providing excellent safety and excellent life characteristics and conductivity even under high voltage conditions.
  • the present invention was completed by confirming.
  • Patent Document 1 KR2009-0018981 A
  • the present invention has been made to solve the above problems, an object of the present invention by coating the entire surface of the positive electrode active material with a nano-film capable of lithium ion migration, it effectively suppresses side reactions between the positive electrode active material and the electrolyte solution and excellent safety. At the same time, to provide a surface-coated positive electrode active material having excellent lifespan characteristics under high temperature and high voltage conditions as well as excellent conductivity.
  • Another object of the present invention to provide a method for producing the surface-coated positive electrode active material.
  • Still another object of the present invention is to provide a positive electrode including the surface-coated positive electrode active material.
  • another object of the present invention is to provide a lithium secondary battery including a separator interposed between the positive electrode, the negative electrode and the positive electrode and the negative electrode.
  • the present invention is a positive electrode active material; And a nano coating including polyimide (PI) and carbon black coated on the surface of the positive electrode active material, wherein the nano coating includes the polyimide and carbon black in a weight ratio of 0.5 to 5 by weight.
  • a coated cathode active material is provided.
  • the present invention comprises the steps of preparing a mixed solution in which carbon black is mixed and dispersed in an organic solvent in which a polyamic acid is diluted; Dispersing a positive electrode active material in the mixed solution to form a film including polyamic acid and carbon black on the surface of the positive electrode active material; And imidizing the positive electrode active material having the coating formed thereon, wherein the carbon black is used in an amount of 0.05 wt% to 5 wt% based on 100 wt% of the positive electrode active material. It provides a method of manufacturing.
  • the present invention provides a positive electrode including the surface-coated positive electrode active material.
  • the present invention provides a lithium secondary battery including the positive electrode, the negative electrode, and a separator interposed between the positive electrode and the negative electrode.
  • the positive electrode active material according to the present invention has a polyimide and carbon black, especially an iodine number of 200 mg / g to 400 mg / g, and an oil absorption number of 0.1 cc / g to 0.2 cc / g. Since the surface is coated with a nano-film including phosphorous carbon black, direct contact between the positive electrode active material and the electrolyte may be prevented, thereby preventing side reactions between the positive electrode active material and the electrolyte.
  • the life characteristics of the lithium secondary battery using the positive electrode including the positive electrode active material surface-coated with the nano-film according to the present invention can be significantly improved, in particular, the life characteristics and conductivity at high temperature and high voltage conditions can be improved.
  • Example 1 is an electron microscope (FE-SEM) photograph of the surface of a cathode active material surface-coated with a nano-film including polyimide and carbon black prepared in Example 1 of the present invention.
  • FIG. 2 is an electron microscope (FE-SEM) photograph of the surface of the uncoated positive electrode active material prepared in Comparative Example 1.
  • FIG. 2 is an electron microscope (FE-SEM) photograph of the surface of the uncoated positive electrode active material prepared in Comparative Example 1.
  • the present invention provides a surface-coated positive electrode active material having excellent safety and excellent life characteristics and conductivity at high temperature and high voltage conditions.
  • the surface-coated positive electrode active material according to an embodiment of the present invention is a positive electrode active material; And a nano coating comprising polyimide (PI) and carbon black coated on the surface of the positive electrode active material, wherein the nano coating includes the polyimide and carbon black in a weight ratio of 0.5 to 5 by weight.
  • PI polyimide
  • the nano-film according to the present invention is a lithium ion transfer is not an ion insulating layer, such as inorganic oxide surface coating layer generally known in the art, the nano-film as described above may include polyimide (PI) and carbon black Can be.
  • the nano-film may include a lithium ion migration by including polyimide (PI), and the electronic conductivity may be improved by including carbon black.
  • the nanofilm may surround the entire surface of the positive electrode active material, and the nanofilm surrounding the surface of the positive electrode active material may prevent direct contact between the positive electrode active material and the electrolyte, thereby causing side reactions between the positive electrode active material and the electrolyte. It can be suppressed. As a result, it is possible to improve the safety and lifespan characteristics of the lithium secondary battery using the positive electrode including the positive electrode active material coated with the nano-film, and in particular, not only general voltage conditions, but also high temperature and high voltage conditions The conductivity may be excellent.
  • the polyimide included in the nano-film may serve as a protective film to prevent the positive electrode active material from directly contacting the electrolyte.
  • the polyimide is a generic term for a polymer having an acid imide structure, and can be obtained by synthesizing using an aromatic anhydride and an aromatic diamine.
  • the polyimide can be obtained by imidization reaction using a polyamic acid as described below.
  • the carbon black included in the nano-film is very excellent in electrical conductivity and lithium ion conductivity may serve to provide a path (path) to react with lithium ions in the electrode, the nano-film is coated on the surface During the charge and discharge cycle of the lithium secondary battery including the positive electrode active material, the current and voltage distribution in the electrode may be maintained uniformly, thereby greatly improving the life characteristics.
  • the carbon black according to the present invention may have a value in which the iodine value and the oil absorption number are selected within a specific numerical range.
  • iodine number used in the present invention refers to the amount of halogen absorbed in the case of reacting halogen or fat to fatty acids or fatty acids using a reaction in which halogen is added to a double bond to 100 g of a sample.
  • the amount of iodine to be absorbed is expressed in g, which is used as a numerical value representing the number of double bonds of unsaturated fatty acids in the sample. The higher the iodine number, the higher the number of double bonds.
  • the iodine number may be a value measured based on ASTM D-1510 of 200 mg / g to 400 mg / g, the iodine number of the carbon black If it is less than 200 mg / g it may be difficult to sufficiently disperse the carbon black in the nano-film, if it exceeds 400 mg / g may cause a problem that the conductivity is lowered.
  • the number of unsaturated bonds (double bonds) present in the carbon black may be appropriate.
  • the bonding force between the carbon black particles, the bonding strength with the solvent when dispersing in the solvent, and other mixtures The bonding strength of the resin can be controlled appropriately, and the carbon black can be uniformly dispersed when the carbon black is dispersed in the solvent, and the agglomeration can be appropriately performed to ensure the conductive network.
  • OAN Olet Absorption number
  • oil absorption number may be a value measured based on ASTM D-2414 is 100 cc / 100 g to 200 cc / 100 g.
  • the secondary structure formed by agglomeration of the primary particles of carbon black partially has an appropriate shape, and the shape of the secondary structure is appropriate.
  • the carbon black can be smoothly dispersed in a solvent and can secure various routes in securing a conductive network.
  • the carbon black according to the present invention has the iodine value and the oil absorption number, dispersibility in a solvent can be better than that of carbon black generally used, and the shape of the secondary structure is excellent to secure a conductive network. Can be fairly easy.
  • the positive electrode active material according to the present invention is a nano-coating formed on the surface, and when the carbon black is uniformly distributed with the polyimide on the nano-coating, it has better dispersibility and proper 2 It is required to have a car structure. Therefore, it may be difficult to uniformly disperse the carbon black on the nanofilm by the numerical values of the iodine value and the oil absorption number of the carbon black generally used in preparing the electrode slurry.
  • the iodine in the case of the carbon black having the iodine value and the oil absorption number value, the iodine can be distributed fairly uniformly due to its excellent dispersibility when it is distributed on the nanofilm, and because of the uniform and excellent secondary structure As a result, the challenge network can be secured.
  • the carbon black may be a mixture of primary particles, secondary particles or primary particles and secondary particles, when the carbon black is the primary particles, the average particle diameter of the carbon black is 10 nm to 100 When the carbon black is secondary particles, the average particle diameter of the carbon black may be less than 1000 nm. In addition, when the carbon black is secondary particles, the secondary particles may be pulverized to have an average particle diameter similar to that of the primary particles.
  • the surface of the carbon black is hydrophobized.
  • the surface hydrophobization treatment is not particularly limited and may be carried out by methods commonly known in the art, for example, carbon black is heat-treated in an air or nitrogen atmosphere at a temperature in the range of 450 to 550 ° C. and acid solution or alkali. It may be carried out by dispersing in a perfluorinated compound after supporting the solution by pretreatment.
  • the nano-film according to the present invention may include the polyimide and carbon black in a ratio of 1: 0.5 to 5 by weight. If the weight ratio of the polyimide and the carbon black is less than 1: 0.5, it may be difficult to obtain sufficient electrical conductivity. If the weight ratio is greater than 1: 5, the carbon black may be detached from the nano-film.
  • the carbon black may be included in an amount of 0.05 wt% to 5 wt% with respect to 100 wt% of the total surface coated positive active material, and preferably 0.2 wt% to 2 wt%.
  • the nanofilm thickness may be 1 nm to 200 nm, preferably 5 nm to 50 nm.
  • the thickness of the nanofilm is less than 1 nm, the side reaction effect of the positive electrode active material and the electrolyte due to the nanofilm and the synergistic effect of the electrical conductivity may be insignificant.
  • the thickness of the nano-film exceeds 200 nm, the thickness of the nano-film is excessively increased, the mobility of the lithium ions is hindered, the resistance may increase.
  • the cathode active material according to the present invention may be applied to a general voltage and a high voltage, and may be used without particular limitation as long as it is a compound capable of reversibly inserting / desorbing lithium.
  • the positive electrode active material according to an embodiment of the present invention is a spinel lithium transition metal oxide having a hexagonal layered rock salt structure, olivine structure, cubic structure having a high capacity characteristics, in addition to V 2 O 5 , TiS, MoS It may include any one selected from the group consisting of two or more of these complex oxides.
  • the cathode active material may include any one selected from the group consisting of oxides of Formulas 1 to 3, and V 2 O 5 , TiS, and MoS, or a mixture of two or more thereof:
  • X b (M Al, Mg, Ni, Co, Mn, Ti, Ga, Cu, V, Nb, Zr, Ce, In, Zn and Y
  • the present invention provides a method for producing the surface-coated positive electrode active material.
  • Method for producing a surface-coated positive electrode active material comprises the steps of preparing a mixed solution in which carbon black is mixed and dispersed in an organic solvent in which polyamic acid is diluted (step 1); Dispersing a cathode active material in the mixed solution to form a film including polyamic acid and carbon black on the surface of the cathode active material (step 2); And imidating the positive electrode active material on which the coating is formed (step 3), wherein the carbon black is used in an amount of 0.05 wt% to 5 wt% based on 100 wt% of the positive electrode active material.
  • Step 1 is a step for preparing a mixed solution in which the material forming the nano-film is uniformly dispersed, and may be performed by adding and mixing carbon black to the organic solvent in which the polyamic acid is diluted.
  • the dispersing agent may be further included.
  • the dispersant is not particularly limited as long as it is mixed with the organic solvent in which the carbon black and the polyamic acid are diluted, and may serve to help the carbon black to be uniformly dispersed in the organic solvent.
  • Block polymers such as styrene-butadiene-styrene block polymer or styrene-butadiene-ethylene-styrene block polymer may be applied as a dispersant.
  • step 1 Mixing and dispersing the organic solvent in which carbon black and the polyamic acid are diluted in step 1 may be performed using a mixer that can be driven at a rotational speed of 10,000 rpm or more at normal temperature (about 15 to 30 ° C.).
  • the temperature range and the rotational speed range may be a condition in which the fibrous carbon material may be smoothly dispersed in the organic solvent in which the polyamic acid is diluted. If the temperature is excessively high, the polyimide reaction converts the polyamic acid to polyimide. There is a risk of this happening early.
  • a nano film in which carbon black and polyimide are uniformly dispersed in the positive electrode active material may be formed, thereby facilitating a conductive network. It can be ensured, and the side reaction can be effectively prevented by playing an excellent role in preventing contact with the electrolyte.
  • the polyamic acid according to the present invention is a precursor material for forming the polyimide included in the above-described nanofilm, and may include a four-component polyamic acid.
  • the four-component polyamic acid may be a polyamic acid including pyromellitic dianhydride, biphenyl dianhydride, phenylenediamine, and oxydianiline. Can be.
  • the polyamic acid is not particularly limited and may be prepared and used by a method commonly known in the art, or may be used by purchasing a commercially available material.
  • the polyamic acid may be used as an aromatic anhydride.
  • Aromatic diamines can be obtained by reacting in polar aromatic solvents. At this time, the aromatic anhydride and the aromatic diamine can be reacted with the same equivalent weight.
  • the aromatic anhydride is not particularly limited, for example, phthalic anhydride, pyromellitic dihydride, 3,3'4,4'-biphenyltetracarboxylic dianhydride, 4'4-oxy Diphthalic anhydride, 3,3'4,4'-benzophenonetetracarboxylic dianhydride, trimellitic ethylene glycol, 4,4 '-(4'4-isopropylbiphenoxy) biphthalic It may be any one selected from the group consisting of an anhydride and a trimellitic anhydride, or a mixture of two or more thereof.
  • aromatic diamine is not particularly limited, for example, 4,4'-oxydianiline, p-phenyl diamine, 2,2-bis (4- (4-aminophenoxy ) -Phenyl) propane, p-methylenedianiline, propyltetramethyldisiloxane, polyaromatic amine, 4,4'-diaminodiphenyl sulfone, 2,2'-bis (trifluoromethyl) -4,4 It may be any one selected from the group consisting of '-diaminobiphenyl and 3,5-diamino-1,2,4-triazole, or a mixture of two or more thereof.
  • the polyamic acid may be used in an amount of 0.1 wt% to 1 wt% based on 100 wt% of the organic solvent.
  • the organic solvent is not particularly limited as long as it is a solvent capable of dissolving the polyamic acid, but is selected from the group consisting of cyclohexane, carbon tetrachloride, chloroform, methylene chloride, dimethylformamide, dimethylacetamide and N-methylpyrrolidone. It may be any one or a mixture of two or more thereof.
  • the carbon black according to the present invention may be used in the amount of 0.05% to 5% by weight with respect to 100% by weight of the positive electrode active material, preferably 0.2% to 2% by weight.
  • the positive electrode active material in order to form a film on the surface of the positive electrode active material, the positive electrode active material is dispersed in the mixed solution prepared in step 1 to form a film containing polyamic acid and carbon black on the surface of the positive electrode active material, the mixing
  • the positive electrode active material may be added to the solution, uniformly dispersed, and heated and concentrated to remove the solvent.
  • Dispersion of the positive electrode active material is not particularly limited, but for example, the positive electrode active material may be added to the mixed solution, followed by stirring for 1 hour or more using a high speed stirrer.
  • Step 3 is a step of imidizing the cathode active material including the film prepared in step 2 to produce a cathode active material having a nano-film formed on the surface.
  • the positive electrode active material including the film obtained in step 2 is heated to a rate of 3 ° C./minute at intervals of 50 ° C. to 100 ° C. to about 300 ° C. to 400 ° C., and 10 minutes to 300 ° C. in a range of 300 ° C. to 400 ° C. By holding for 120 minutes.
  • the temperature is raised at intervals of 50 to 100 ° C., for example, it may be maintained for 10 minutes to 120 minutes, and then heated again.
  • the positive electrode active material including the coating is heated at a rate of 3 ° C./minute at 60 ° C., 120 ° C., 200 ° C., 300 ° C., and 400 ° C., respectively, at 60 ° C. for 30 minutes, at 120 ° C. for 30 minutes,
  • the imidation reaction may be advanced by maintaining at 200 ° C. for 60 minutes, at 300 ° C. for 60 minutes, and at 400 ° C. for 10 minutes.
  • the present invention provides a positive electrode including the surface-coated positive electrode active material.
  • the positive electrode can be prepared by conventional methods known in the art. For example, a solvent, a binder, a conductive agent, a filler, and a dispersant may be mixed and stirred in the surface-coated positive electrode active material to prepare a positive electrode active material slurry, which is then coated (coated) on a positive electrode current collector, compressed, and then dried to obtain a positive electrode. Can be prepared.
  • the positive electrode current collector may be generally used having a thickness of 3 ⁇ m to 500 ⁇ m, any of the positive electrode active material slurry is a metal that can easily adhere as long as it has a high conductivity without causing chemical changes in the battery. Can also be used.
  • Non-limiting examples of the positive electrode current collector include copper, stainless steel, aluminum, nickel, titanium, calcined carbon or a surface treated with carbon, nickel, titanium, or silver on the surface of aluminum or stainless steel, and an aluminum-cadmium alloy. Can be used.
  • fine concavo-convex is formed on the surface, or may be used in various forms such as film, sheet, foil, net, porous body, foam, nonwoven fabric.
  • the solvent for forming the positive electrode includes an organic solvent such as NMP (N-methyl pyrrolidone), DMF (dimethyl formamide), acetone, dimethyl acetamide or water, and these solvents alone or in combination of two or more. Can be mixed and used. The amount of the solvent used is sufficient to dissolve and disperse the positive electrode active material, the binder, and the conductive agent in consideration of the coating thickness of the slurry and the production yield.
  • NMP N-methyl pyrrolidone
  • DMF dimethyl formamide
  • acetone dimethyl acetamide or water
  • the binder is a component that assists the bonding between the positive electrode active material and the conductive agent and the positive electrode current collector, for example, polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene Fluoride (polyvinylidenefluoride), polyacrylonitrile, 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 and hydrogens thereof , Polymers substituted with Na or Ca, or Various kinds of binder polymers such as various copolymers can be used.
  • PVDF-co-HFP poly
  • the conductive agent is not particularly limited as long as it has conductivity without causing chemical change in the battery.
  • Examples of the conductive agent 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.
  • the filler is a component that suppresses the expansion of the positive electrode and can be used or not as necessary, and is not particularly limited as long as it is a fibrous material without causing chemical change in the battery.
  • an olefin polymer such as polyethylene or polypropylene may be used. ; It may be a fibrous material such as glass fiber, carbon fiber.
  • the dispersant may be an aqueous dispersant or an organic dispersant such as N-methyl-2-pyrrolidone.
  • the coating may be performed by a method commonly known in the art, but for example, the positive electrode active material slurry may be distributed on the upper surface of the positive electrode current collector and then uniformly dispersed using a doctor blade or the like. Can be.
  • the method may be performed by a die casting method, a comma coating method, a screen printing method, or the like.
  • the drying is not particularly limited, but may be performed within one day in a vacuum oven at 50 to 200 °C.
  • the present invention provides a lithium secondary battery including the positive electrode, the negative electrode, and a separator interposed between the positive electrode and the negative electrode.
  • the lithium secondary battery according to an embodiment of the present invention comprises a separator and an electrolyte interposed between the positive electrode and the negative electrode, the positive electrode and the negative electrode including a positive electrode active material coated on the surface of the nano-film including polyimide and carbon black It is characterized by including.
  • the lithium secondary battery according to an embodiment of the present invention may exhibit excellent life characteristics in both the normal voltage and the high voltage region, and may be particularly excellent in the high temperature and high voltage region.
  • the charging voltage of the lithium secondary battery is characterized in that the 4.2V to 5.0V.
  • general voltage refers to the case where the charging voltage of the lithium secondary battery is in the range of 3.0V to less than 4.2V
  • high voltage is the region of the charge voltage is 4.2V to 5.0V range It may mean a case
  • high temperature may mean a range of 45 to 65 °C.
  • the negative electrode is not particularly limited, but may be prepared by applying a negative electrode active material slurry on the upper surface of one side of the negative electrode current collector and then drying the negative electrode active material slurry, in addition to the negative electrode active material, such as a binder, a conductive agent, a filler, and a dispersant as necessary. It may include an additive.
  • a carbon material lithium metal, silicon, tin, or the like, in which lithium ions may be occluded and released, may be used.
  • a carbon material may be used, and as the carbon material, both low crystalline carbon and high crystalline carbon may be used.
  • Soft crystalline carbon and hard carbon are typical low crystalline carbon, and high crystalline carbon is natural graphite, Kish graphite, pyrolytic carbon, liquid crystal pitch carbon fiber.
  • High temperature calcined carbon such as (mesophase pitch based carbon fiber), meso-carbon microbeads, Mesophase pitches and petroleum or coal tar pitch derived cokes.
  • the negative electrode current collector may be the same as or included with the aforementioned positive electrode current collector, and additives such as binders, conductive agents, fillers, and dispersants used in the negative electrode may be the same as those used in the aforementioned positive electrode manufacture. It may be included.
  • the separator may be an insulating thin film having high ion permeability and mechanical strength, and may generally have a pore diameter of 0.01 ⁇ m to 10 ⁇ m and a thickness of 5 ⁇ m to 300 ⁇ m.
  • Such separators include porous polymer films made of polyolefin-based polymers such as ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers and ethylene / methacrylate copolymers. These may be used alone or in combination thereof, or a conventional porous nonwoven fabric, for example, a non-woven fabric made of high melting glass fibers, polyethylene terephthalate fibers, or the like may be used, but is not limited thereto.
  • the electrolyte used in the present invention may include a lithium salt commonly used in the electrolyte, and is not particularly limited.
  • the lithium salt of the anion is F -, Cl -, Br - , 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 -, SCN - one selected from the group consisting of - and (CF 3 CF 2 SO 2) 2 N It may be abnormal.
  • Examples of the electrolyte used in the present invention 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. no.
  • the external shape of the lithium secondary battery of the present invention is not particularly limited, but may be cylindrical, square, pouch type, or coin type using a can.
  • the lithium secondary battery according to the present invention may not only be used in a battery cell used as a power source for a small device, but also preferably used as a unit battery in a medium-large battery module including a plurality of battery cells.
  • Preferred examples of the medium-to-large device include, but are not limited to, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and electric power storage systems.
  • the positive electrode active material coated on the surface of the film containing polyamic acid and carbon black was prepared by increasing the temperature to the boiling point of the solvent while evaporating the solvent while evaporating the solvent.
  • the cathode active material coated on the surface of the film containing the polyamic acid and carbon black prepared above was heated to 60 ° C., 120 ° C., 200 ° C., 300 ° C., and 400 ° C. at a rate of 3 ° C./min, respectively, at 60 ° C. for 30 minutes. , 30 minutes at 120 ° C, 60 minutes at 200 ° C, 60 minutes at 300 ° C, and 10 minutes at 400 ° C to proceed with the imidization reaction.
  • LiNi 0 coated on the surface of the nano-film including the polyimide and carbon black as the imidization reaction is completed . 6 Mn 0 . 2 Co 0 .
  • a 2 0 2 positive electrode active material was prepared. At this time, the polyimide and carbon black in the prepared nano-film showed a weight ratio of 1: 0.5.
  • Polyimide and carbon black were included in the same manner as in Preparation Example 1, except that the amount of polyamic acid and carbon black added so that the polyimide and carbon black had a weight ratio of 1:15 in the finally prepared nanofilm. LiNi 0 coated on the surface . 6 Mn 0 . 2 Co 0 . A 2 0 2 positive electrode active material was prepared.
  • LiNi 0 prepared in Preparation Example 1 . 6 Mn 0 . 2 Co 0 . 2 O 2 positive electrode active material, carbon black as a conductive agent, polyvinylidene fluoride (PVdF) as a binder is mixed in a weight ratio of 95: 3: 2, and N-methyl-2-pyrrolidone (NMP) solvent It was added to to prepare a positive electrode active material slurry.
  • the positive electrode active material slurry is applied to a thin film of aluminum (Al), which is a positive electrode current collector having a thickness of about 20 ⁇ m, and dried at 130 ° C. for 2 hours to prepare a positive electrode, followed by roll press to prepare a positive electrode. It was.
  • Al aluminum
  • Lithium metal foil was used as the negative electrode.
  • LiPF 6 non-aqueous electrolyte was prepared by adding LiPF 6 to a non-aqueous electrolyte solvent prepared by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 1: 2 as an electrolyte.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • a lithium secondary battery was manufactured in the same manner as in Example 1, except that the cathode active material prepared in Preparation Example 2 was used instead of the cathode active material prepared in Preparation Example 1.
  • a lithium secondary battery was manufactured in the same manner as in Example 1, except that the cathode active material prepared in Preparation Example 3 was used instead of the cathode active material prepared in Preparation Example 1.
  • a lithium secondary battery was manufactured in the same manner as in Example 1, except that the cathode active material prepared in Preparation Example 4 was used instead of the cathode active material prepared in Preparation Example 1.
  • a lithium secondary battery was manufactured in the same manner as in Example 1, except that the cathode active material prepared in Preparation Example 5 was used instead of the cathode active material prepared in Preparation Example 1.
  • a lithium secondary battery was manufactured in the same manner as in Example 1, except that the cathode active material prepared in Comparative Preparation Example 1 was used instead of the cathode active material prepared in Preparation Example 1.
  • a lithium secondary battery was manufactured in the same manner as in Example 1, except that the cathode active material prepared in Comparative Preparation Example 2 was used instead of the cathode active material prepared in Preparation Example 1.
  • a lithium secondary battery was manufactured in the same manner as in Example 1, except that the cathode active material prepared in Comparative Preparation Example 3 was used instead of the cathode active material prepared in Preparation Example 1.
  • a lithium secondary battery was manufactured in the same manner as in Example 1, except that the cathode active material prepared in Comparative Preparation Example 4 was used instead of the cathode active material prepared in Preparation Example 1.
  • a lithium secondary battery was manufactured in the same manner as in Example 1, except that the cathode active material prepared in Comparative Preparation Example 5 was used instead of the cathode active material prepared in Preparation Example 1.
  • a lithium secondary battery was manufactured in the same manner as in Example 1, except that the cathode active material prepared in Comparative Preparation Example 6 was used instead of the cathode active material prepared in Preparation Example 1.
  • a lithium secondary battery was manufactured in the same manner as in Example 1, except that the cathode active material prepared in Comparative Preparation Example 7 was used instead of the cathode active material prepared in Preparation Example 1.
  • a lithium secondary battery was manufactured in the same manner as in Example 1, except that the cathode active material prepared in Comparative Preparation Example 8 was used instead of the cathode active material prepared in Preparation Example 1.
  • Figure 1 is LiNi 0 coated on the surface of the nano-film including the polyimide and carbon black prepared in Example 1 of the present invention . 6 Mn 0 . 2 Co 0 .
  • the coated LiNi 0 . 6 Mn 0 . 2 Co 0 As a result of observing the surface of the 2 O 2 particles, the coated LiNi 0 . 6 Mn 0 . 2 Co 0 . It can be seen that a nanofilm having a thickness of several nanometers in which polyimide and carbon black are well dispersed is formed on the surface of the 2 O 2 particles.
  • FIG. 2 is LiNi 0 of Comparative Preparation Example 1 . 6 Mn 0 . 2 Co 0 . Pure LiNi 0 with 2 O 2 particles and uncoated on the surface . 6 Mn 0 . 2 Co 0 . 2 O 2 particles, FIG. 3 shows LiNi 0. Surface coated with polyimide prepared in Comparative Preparation Example 2 . 6 Mn 0 . 2 Co 0 . As 2 O 2 particles, no carbon black was observed.
  • the lithium secondary batteries of Examples 1 to 5 were similar in the initial charge and discharge capacity compared to the lithium secondary batteries of Comparative Examples 1 to 8, but the rate-rate characteristics (C-rate) and 50 It can be seen that the capacity retention rate is remarkably excellent.
  • the positive electrode active material according to the present invention is compared with the lithium secondary batteries of Comparative Examples 3 to 8, which are coated with polyimide and carbon black, but which are not carbon black according to the present invention or include a positive electrode active material which is out of the mixing ratio. It was confirmed that the lithium secondary batteries of Examples 1 to 5, including the rate-rate characteristics and the 50th capacity retention rate were excellent, in particular, the 50th capacity retention rate was significantly increased.

Abstract

La présente invention concerne un matériau actif d'électrode positive revêtu en surface, son procédé de préparation, et une batterie rechargeable au lithium le comprenant. Plus spécifiquement, la présente invention porte sur un matériau actif d'électrode positive qui est revêtu en surface avec un nanofilm contenant du polyimide (PI) et du noir de carbone, sur son procédé de préparation, et sur une batterie rechargeable au lithium le comprenant. Le matériau actif d'électrode positive qui est revêtu en surface avec ce nanofilm peut empêcher un contact direct entre un matériau actif d'électrode positive et un électrolyte, et peut ainsi supprimer une réaction secondaire entre le matériau actif d'électrode positive et l'électrolyte, peut améliorer sensiblement les caractéristiques de durée de vie d'une batterie rechargeable au lithium utilisant une électrode positive contenant le matériau actif d'électrode positive, et peut en particulier améliorer les caractéristiques de durée de vie et la conductivité dans des conditions de température élevée et de tension élevée.
PCT/KR2015/008915 2014-08-26 2015-08-26 Matériau actif d'électrode positive revêtu en surface, son procédé de préparation, et batterie rechargeable au lithium le comprenant WO2016032223A1 (fr)

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EP15835187.4A EP3188290B1 (fr) 2014-08-26 2015-08-26 Matériau actif d'électrode positive enduit de surface, procédé de préparation de celui-ci, et batterie secondaire au lithium comprenant celui-ci
CN201580030667.9A CN106663799B (zh) 2014-08-26 2015-08-26 表面涂覆的正极活性材料、其制备方法和包含其的锂二次电池
US15/039,266 US10476082B2 (en) 2014-08-26 2015-08-26 Surface coated positive electrode active material, preparation method thereof and lithium secondary battery including the same

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KR10-2014-0111504 2014-08-26
KR20140111504 2014-08-26
KR10-2015-0117752 2015-08-21
KR1020150117752A KR101714892B1 (ko) 2014-08-26 2015-08-21 표면 코팅된 양극 활물질, 이의 제조방법, 및 이를 포함하는 리튬 이차전지

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