CN106803586B - Composite positive electrode material, preparation method thereof and lithium ion battery containing composite positive electrode material - Google Patents

Composite positive electrode material, preparation method thereof and lithium ion battery containing composite positive electrode material Download PDF

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CN106803586B
CN106803586B CN201710117454.0A CN201710117454A CN106803586B CN 106803586 B CN106803586 B CN 106803586B CN 201710117454 A CN201710117454 A CN 201710117454A CN 106803586 B CN106803586 B CN 106803586B
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indium
positive electrode
tin
conductive film
electrode material
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CN106803586A (en
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任付金
吴小珍
杨顺毅
庞钧友
黄友元
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Shenzhen City Battery Nanometer Technology Co ltd
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Shenzhen City Battery Nanometer Technology Co ltd
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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • 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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • H01M4/624—Electric conductive 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

Abstract

The invention provides a composite anode material, a preparation method thereof and a lithium ion battery containing the composite anode material. The composite anode material comprises an anode material and a conductive film which is completely and uniformly coated on the surface of the anode material. The invention also provides a preparation method of the composite cathode material, and the method can ensure that the conductive film is uniformly coated on the surface of the cathode material and realizes complete coating. In the composite cathode material, the conductive film with stronger conductivity is completely and uniformly coated, so that the direct contact between the electrolyte and the cathode material can be prevented, the occurrence of side reactions is reduced, and the rate capability, the cycle performance and the safety performance of a battery can be improved. Compared with a battery made of the anode material without the conductive film, the 5C rate performance of the composite material is improved by 15-28%, the capacity retention rate after 50 cycles is improved by 7-11%, the heat release temperature is improved by 20-30 ℃, and the safety performance is improved.

Description

Composite positive electrode material, preparation method thereof and lithium ion battery containing composite positive electrode material
Technical Field
The invention belongs to the field of lithium ion battery anode materials, and relates to a composite anode material, a preparation method thereof and a lithium ion battery containing the composite anode material, in particular to a composite anode material with an ITO nano conductive film coating the anode material, a preparation method thereof and a lithium ion battery containing the composite anode material.
Background
With the technological progress and the rapid development of human society, the industrialization process is accelerated continuously, and the demand of people on energy is increased continuously. Traditional fossil fuels such as coal, oil and natural gas are largely exploited and used, so that the non-renewable fossil energy is gradually exhausted, and the energy crisis problem is severe. During the combustion process of fossil fuel, a large amount of dust and harmful gas are generated, which causes serious environmental pollution and brings great harm to the ecological environment and the life and body health of people.
In order to relieve the energy shortage condition and protect the ecological environment, the sustainable energy use mode must be changed. With the advancement of technology and the development of society, a large number of portable electronic devices, electric vehicles, and the like are introduced into the life of people, and thus, the appearance of high-performance batteries is urgently needed. The conventional secondary battery has been difficult to satisfy the demand of higher performance of the battery for electronic products, power generation systems, new energy vehicles, and the like at the present stage.
Lithium ion batteries have the advantages of higher energy density, power density, higher working voltage, better cycle performance, lower self-discharge rate and the like, are known as green power sources, are considered as the most ideal chemical energy sources by international society, and are widely applied to electronic products such as mobile phones, notebook computers, electric tools, portable cameras and the like. With the improvement of the existing materials and battery design technologies and the emergence of new materials, the application range of lithium ion batteries is continuously expanded, from the information industry (mobile phones, PDAs and notebook computers) to energy traffic (electric vehicles and power grid peak shaving), and from the space (satellites and spaceships) to the underwater (submarines and underwater robots). The lithium ion battery serves as a new energy source with the most development prospect for human beings, and becomes a research and development hotspot in the present century.
For a lithium ion battery, a positive electrode material, a negative electrode material and an electrolyte are key factors determining the electrochemical performance of the lithium ion battery, and the positive electrode material plays a role as a lithium source in the lithium ion battery, is one of important components of the lithium ion battery, and is a key factor restricting the electrochemical performance of the lithium ion battery such as specific energy, specific power and the like. Currently, commonly used lithium ion battery anode materials mainly include: a positive electrode material having a layered structure comprising lithium cobaltate (LiCoO)2) Lithium nickelate (LiNiO)2) Lithium manganate (LiMnO)2) And a two/three-element composite layered positive electrode material (LiNi)xCoyMnzO2) Etc.; lithium manganate (LiMn) of spinel structure2O4) (ii) a Lithium iron phosphate (LiFePO) having olivine-type structure4) And the like.
Although the lithium ion battery material has many advantages, when used for a power battery, the lithium ion battery material also has many problems to be solved urgently, such as the material cycle performance and the safety performance are far from the requirements, the capacity attenuation under large current is serious, the rate capability is poor, and the like. In order to solve these problems, materials are usually modified by doping and surface coating, etc. to improve the performance of the cathode material.
Chinese invention patent CN105118963A discloses a transparent anode material of a lithium ion battery and a preparation method thereof. The structure of the lithium ion battery comprises a substrate, a charge transmission layer and a lithium ion storage layer, wherein the charge transmission layer and the lithium ion storage layer are arranged on the substrate. Also discloses a preparation method of the transparent anode material of the lithium ion battery, which comprises the following steps: preparing the ITO or AZO charge transmission layer on the cleaned substrate by adopting a nano magnetron sputtering, electron beam evaporation or pulse laser deposition method; preparing a lithium ion storage layer LiV on the charge transport layer in situ by adopting an ion-assisted magnetron sputtering method, an electron beam evaporation method or a pulse laser deposition method3O8. The average transmittance of the prepared transparent anode material of the lithium ion battery in a visible light wave band is 70-80%,the transparent positive electrode material of the lithium ion battery is used for preparing the positive electrode and further assembling the positive electrode into the lithium ion battery, the charge-discharge capacity is high, the cycle stability is good, the first charge-discharge specific capacity is 300-350 mAh/g, the capacity can still be kept above 80% after 100 cycles, and the transparent positive electrode material of the lithium ion battery can be applied to the field of novel transparent lithium ion batteries. However, the positive electrode material prepared by this method is LiV3O8Transparent positive electrode materials, inventive materials and uses are all limited.
Chinese invention patent CN103956458A discloses a lithium ion battery composite positive electrode, a preparation method thereof and application in all solid-state lithium ion batteries. The composite anode of the lithium ion battery consists of an anode active substance, an inorganic solid electrolyte and an oxidation conductive additive; the positive active substance is any one of ternary materials of lithium cobaltate, lithium manganate, lithium iron phosphate and nickel cobalt manganese; the inorganic solid electrolyte is at least one of lithium borate, lithium metaborate and lithium fluoride; the oxide conductive additive is any one of indium tin oxide, indium oxide, tin dioxide, zinc oxide, nickel oxide and ferroferric oxide. The patent also discloses a preparation method of the lithium ion battery composite anode, which comprises the following steps: (1) mixing the positive active substance, the inorganic solid electrolyte and the oxide conductive additive, ball-milling, drying and pressing into a ceramic wafer; (2) and sintering the ceramic wafer to obtain the composite anode. The prepared composite positive electrode has good specific mass capacity, specific area capacity and cycle performance, can be used for preparing all-solid-state lithium ion batteries, and can be used at high temperature. However, the anode material prepared by the method mainly adopts a solid-phase ball milling method to mix and add the powder indium tin oxide into the anode material for sintering, and belongs to the common doping category.
Therefore, the invention of the cathode material with high conductivity, high multiplying power, high safety and good coating is a technical problem in the field of cathode materials of lithium ion batteries.
Disclosure of Invention
In view of the above problems in the prior art, an object of the present invention is to provide a composite cathode material, a method for preparing the same, and a lithium ion battery comprising the same, wherein the composite cathode material comprises a cathode material and a conductive film coated on the surface of the cathode material, and the conductive film having a relatively high conductivity is completely and uniformly coated to block direct contact between an electrolyte and the cathode material, thereby reducing side reactions and improving rate performance, cycle performance, and safety performance of the battery. Compared with a battery made of the anode material without the conductive film, the 5C rate performance of the composite material is improved by 15-28 percent, the capacity retention rate of the composite material after 50 cycles is improved by 7-11 percent, the heat release temperature is improved by 20-30 ℃, and the safety performance is improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a composite cathode material, including a cathode material and a conductive film coated on a surface of the cathode material.
In the composite cathode material, the conductive film is completely coated on the surface of the cathode material and is uniformly coated. The conductive film has stronger conductivity, and the structure that the conductive film and the anode material are completely wrapped can not only prevent the electrolyte from directly contacting with the anode material, reduce the occurrence of side reactions, but also improve the rate capability, the cycle performance and the safety performance of the assembled battery.
The mass ratio of the positive electrode material to the conductive film in the composite positive electrode material is preferably 1 (0.001 to 0.1), for example, 1:0.001, 1:0.002, 1:0.003, 1:0.004, 1:0.005, 1:0.006, 1:0.008, 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.06, 1:0.07, 1:0.08, or 1: 0.1.
Preferably, the cathode material has a chemical composition of LiNixCoyMzO2And/or LiFePO4Wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and z is more than or equal to 0 and less than or equal to 1<1, and x + y + z is 1, and M is selected from any one or a combination of at least two of Mn, Al, Mg, Zr, Zn, Cu or Cr. The positive electrode material may be, for example, but not limited to, LiNi1/3Co1/3Mn1/3O2、LiNi0.6Co0.2Mn0.2O2、LiNi0.8Co0.15Al0.05O2、LiNi1/3Co1/3Mg1/3O2、LiNi0.5Co0.3Mn0.2O2And LiNi0.8Co0.1Al0.1O2And the like.
In the invention, the chemical composition is LiFePO4The cathode material refers to a lithium iron phosphate cathode material.
Preferably, the conductive film has a thickness of the order of nanometers, the conductive film is a nano-conductive film, and the thickness is preferably 0.5nm to 200nm, for example, 0.5nm, 1nm, 3nm, 7nm, 10nm, 15nm, 20nm, 25nm, 30nm, 34.5nm, 38nm, 40nm, 42nm, 44nm, 46nm, 50nm, 54nm, 58nm, 62nm, 66nm, 70nm, 75nm, 78nm, 80nm, 85nm, 90nm, 95nm, 100nm, 110nm, 115nm, 120nm, 125nm, 130nm, 135nm, 140nm, 150nm, 160nm, 175nm, 185nm, or 200 nm.
Preferably, the chemical composition of the conductive film is Indium Tin Oxide (ITO).
Preferably, the indium tin oxide is tin-doped indium oxide, and the indium tin oxide is formed by In2O3And SnO2And (4) forming.
Preferably, the In2O3And SnO2The mass ratio of (3 to 10):1, for example, 3:1, 4:1, 4.5:1, 5:1, 6:1, 6.5:1, 7:1, 8:1, 8.5:1, 9:1 or 10:1, preferably 9: 1.
In a second aspect, the present invention provides a method for preparing the composite cathode material according to the first aspect, the method comprising: and coating the conductive film on the surface of the anode material by adopting a spray pyrolysis method to prepare the composite anode material.
Preferably, the conductive film is an indium tin oxide conductive film. The ITO conductive film has high conductivity and a resistivity of 10-3Ω·cm～10-5Omega cm is close to the resistivity of metal, and the electrolyte is completely wrapped on the surface of the anode material to prevent the electrolyte from directly contacting with the anode material, so that the occurrence of side reaction is reduced, and the rate capability, the cycle performance and the safety performance of the battery are improved.
Preferably, the method comprises the steps of:
(1) preparing a precursor solution of the conductive film;
(2) adding a positive electrode material into the conductive film precursor solution obtained in the step (1) to obtain slurry, and adding a thickening agent to adjust the viscosity of the slurry to obtain dispersion liquid;
(3) and (3) carrying out spray thermal decomposition on the dispersion liquid obtained in the step (2), and coating a conductive film on the surface of the positive electrode material to obtain the composite positive electrode material.
Preferably, the conductive film precursor solution in step (1) is an indium tin oxide precursor solution.
Preferably, the preparation process of the indium tin oxide precursor solution is as follows: dissolving an indium-based material and a tin-based material in a solvent, and stirring to obtain an indium tin oxide precursor solution;
preferably, the indium-based material is any one of indium nitrate, indium chloride, indium sulfate, indium acetate, or indium oxalate, or a combination of at least two of the following typical but non-limiting examples: combinations of indium nitrate and indium chloride, indium nitrate and indium sulfate, indium chloride and indium acetate, indium nitrate, indium chloride, and indium acetate, and the like. But is not limited to the indium-based materials listed above, and other indium-based materials commonly used in the art may also be used in the present invention.
Preferably, the tin-based material is any one of tin nitrate, tin chloride, tin sulfate, tin acetate or stannous oxalate or a combination of at least two of the following typical but non-limiting examples: a combination of tin nitrate and tin chloride, a combination of tin nitrate and tin sulfate, a combination of tin nitrate and tin acetate, a combination of tin chloride, tin sulfate, and tin acetate, and the like. But not limited to the above-listed tin-based materials, other tin-based materials commonly used in the art may also be used in the present invention.
Preferably, the molar ratio of the indium-based material to the tin-based material is (1-20): 1, for example, 1:1, 2:1, 2.5:1, 3.5:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 15:1, 16:1, 18:1, 19:1, or 20: 1.
Preferably, the solvent is any one of methanol, ethanol, benzyl alcohol or ethylene glycol or a combination of at least two of them.
Preferably, the stirring speed is 50r/min to 500r/min, such as 50r/min, 75r/min, 100r/min, 120r/min, 130r/min, 150r/min, 175r/min, 200r/min, 220r/min, 245r/min, 275r/min, 300r/min, 325r/min, 350r/min, 400r/min, 430r/min, 450r/min or 500r/min, etc.
Preferably, the stirring time is 30min to 300min, such as 30min, 45min, 60min, 80min, 100min, 120min, 150min, 180min, 200min, 210min, 245min, 260min, 270min, 285min, 300min, and the like.
Preferably, the chemical composition of the cathode material in the step (2) is LiNixCoyMzO2Wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and z is more than or equal to 0 and less than or equal to 1<1, and x + y + z is 1, M is selected from any one or a combination of at least two of Mn, Al, Mg, Zr, Zn, Cu or Cr, and the cathode material may be, for example, but not limited to, LiNi1/3Co1/3Mn1/3O2、LiNi0.6Co0.2Mn0.2O2、LiNi0.8Co0.15Al0.05O2、LiNi1/3Co1/3Mg1/3O2、LiNi0.5Co0.3Mn0.2O2And LiNi0.8Co0.1Al0.1O2And the like.
Preferably, the adding of the positive electrode material in the step (2) is accompanied by stirring.
Preferably, the stirring is continued for 10min to 120min after the cathode material is added in the step (2), for example, 10min, 20min, 30min, 40min, 50min, 60min, 75min, 85min, 100min, 110min or 120min, and the like, and preferably 30 min.
Preferably, the solid content of the slurry of step (2) is 20 wt% to 60 wt%, such as 20 wt%, 23 wt%, 25 wt%, 30 wt%, 32.5 wt%, 35 wt%, 38 wt%, 40 wt%, 43 wt%, 45 wt%, 47.5 wt%, 50 wt%, 55 wt%, or 60 wt%, etc.
Preferably, the thickener in step (2) is a solid alcohol thickener FR 400.
Preferably, the mass ratio of the conductive film precursor solution to the thickener in step (2) is 1 (0.0001 to 0.1), for example, 1:0.0001, 1:0.0002, 1:0.0003, 1:0.0005, 1:0.0006, 1:0.0008, 1:0.001, 1:0.003, 1:0.005, 1:0.006, 1:0.007, 1:0.008, 1:0.01, or the like. In the present invention, the thickener is preferably added in accordance with the adjustment of the slurry viscosity until the cathode material does not settle any more.
Preferably, the dispersion is continuously stirred while the spray pyrolysis is performed in step (3).
Preferably, when the spray pyrolysis is performed in the step (3), the carrier gas for spraying is compressed air.
Preferably, the carrier gas pressure in the spray pyrolysis in the step (3) is 3kg/m2～10kg/m2For example, 3kg/m2、4kg/m2、5kg/m2、6kg/m2、7kg/m2、8kg/m2、8.5kg/m2、9kg/m2Or 10kg/m2And the like.
Preferably, when the spray pyrolysis is carried out in step (3), the dispersion flow rate is 5ml/min to 500ml/min, such as 5ml/min, 10ml/min, 20ml/min, 35ml/min, 50ml/min, 65ml/min, 85ml/min, 100ml/min, 120ml/min, 150ml/min, 180ml/min, 200ml/min, 220ml/min, 240ml/min, 275ml/min, 300ml/min, 330ml/min, 360ml/min, 385ml/min, 400ml/min, 425ml/min, 450ml/min, or 500ml/min, etc.
Preferably, in the spray pyrolysis in the step (3), the temperature of the spray is 100 to 300 ℃, for example, 100 ℃, 125 ℃, 150 ℃, 165 ℃, 180 ℃, 200 ℃, 210 ℃, 220 ℃, 235 ℃, 250 ℃, 260 ℃, 280 ℃ or 300 ℃.
Preferably, when the spray pyrolysis is performed in step (3), the pyrolysis temperature is 300 to 800 ℃, for example, 300 ℃, 325 ℃, 350 ℃, 380 ℃, 400 ℃, 420 ℃, 440 ℃, 460 ℃, 480 ℃, 500 ℃, 525 ℃, 550 ℃, 575 ℃, 600 ℃, 630 ℃, 660 ℃, 700 ℃, 750 ℃, or 800 ℃.
Preferably, when the spray pyrolysis is performed in step (3), the pyrolysis time is 2h to 20h, such as 2h, 3h, 5h, 6h, 8h, 10h, 12h, 13h, 15h, 16h, 18h, 20h, and the like.
In a third aspect, the present invention provides another method for preparing the composite cathode material according to the first aspect, the method includes: the composite cathode material is prepared by coating a conductive film on the surface of the cathode material by a Chemical Vapor Deposition (CVD) method using a coating material.
Preferably, the conductive film is an indium tin oxide conductive film. When the conductive film is an indium tin oxide conductive film, the coating raw materials are an indium metal organic compound and a tin metal organic compound.
Preferably, the indium metal organic compound is any one of or a combination of at least two of indium acetylacetonate, trimethylindium, triethylindium, triphenylindium or indium diethylacetate, typical but non-limiting examples of which are: a combination of indium acetylacetonate and trimethylindium, a combination of indium acetylacetonate and triethylindium, a combination of indium trimethylacetate and indium diethylacetate, a combination of indium acetylacetonate, triethylindium and triphenylindium, a combination of indium acetylacetonate, trimethylindium and triethylindium, and the like. However, the indium metal organic compound is not limited to the above-mentioned examples, and other indium metal organic compounds commonly used in the art may be used in the present invention.
Preferably, the tin metal organic compound has a chemical composition of RxSnY, wherein R is any one or combination of alkyl or aryl, Y is halogen, and x is an integer of 0-4. Said x is for example 0, 1, 2, 3 and 4.
Preferably, the tin metal organic compound is any one of trimethyl tin, tetramethyl tin, triethyl tin, triphenyl tin or tin tetrachloride or a combination of at least two of the foregoing. Typical but non-limiting examples of such combinations are: combinations of trimethyltin and tetramethyltin, trimethyltin and stannic tetrachloride, trimethyltin, tetramethyltin and triethyltin, and the like. However, the tin organometallic compound is not limited to the above-mentioned examples, and other tin organometallic compounds commonly used in the art may be used in the present invention.
In the present invention, the indium metal organic compound and the tin metal organic compound as the coating raw materials may be in a gas phase or a non-gas phase. If the coating raw material is in a gas phase, directly introducing the gas-phase coating raw material into the rotary furnace by using carrier gas; if the coating raw material is in a non-gaseous phase, certain measures are taken to ensure that the coating raw material is vaporized and then is introduced into the rotary furnace by carrier gas. The certain measures can be a high-temperature evaporation mode, for example, when indium diethylacetate and tin tetrachloride are used as the coating raw materials, the measures are as follows: putting the indium diethyl acetate into a container with the temperature of 200-400 ℃ to obtain the steam of the indium diethyl acetate; putting tin tetrachloride into a container at 300-500 ℃ to obtain tin tetrachloride steam; the vapor of indium diethylacetate and the vapor of tin tetrachloride were introduced into the reaction furnace separately by a carrier gas.
Preferably, the method for coating the indium tin oxide conductive film on the surface of the cathode material by adopting the chemical vapor deposition method comprises the following steps:
and (2) placing the anode material in a rotary furnace, heating, introducing reaction gas, respectively introducing a gaseous indium metal organic compound and a gaseous tin metal organic compound into the rotary furnace by using carrier gas, carrying out chemical vapor deposition, and coating an indium tin oxide conductive film on the surface of the anode material to obtain the composite anode material.
Preferably, the chemical composition of the cathode material is LiNixCoyMzO2Wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and z is more than or equal to 0 and less than or equal to 1<1, and x + y + z is 1, and M is selected from any one or a combination of at least two of Mn, Al, Mg, Zr, Zn, Cu or Cr. The positive electrode material may be, for example, but not limited to, LiNi1/3Co1/3Mn1/3O2、LiNi0.6Co0.2Mn0.2O2、LiNi0.8Co0.15Al0.05O2、LiNi1/ 3Co1/3Mg1/3O2、LiNi0.5Co0.3Mn0.2O2And LiNi0.8Co0.1Al0.1O2And the like.
Preferably, the heating rate at the time of heating is 0.5 ℃/min to 15 ℃/min, for example, 0.5 ℃/min, 1 ℃/min, 2 ℃/min, 3 ℃/min, 3.5 ℃/min, 4 ℃/min, 5 ℃/min, 6 ℃/min, 7 ℃/min, 8 ℃/min, 10 ℃/min, 11 ℃/min, 12 ℃/min, 13 ℃/min, 14 ℃/min, 15 ℃/min or the like.
Preferably, the reactive gas is oxygen.
Preferably, the reaction gas is introduced at a rate of 1m3/h～5m3H, e.g. 1m3/h、1.2m3/h、1.4m3/h、1.5m3/h、1.6m3/h、1.7m3/h、1.8m3/h、1.9m3/h、2m3/h、2.5m3/h、3m3/h、3.5m3/h、4m3H or 5m3H, etc.
Preferably, the carrier gas is any one of nitrogen, helium, neon, argon, krypton or xenon or a combination of at least two of the same.
Preferably, when the gaseous indium metal organic compound is introduced into the rotary kiln using a carrier gas, the flow rate of the mixed gas of the carrier gas and the gaseous indium metal organic compound is 0.1L/min to 100L/min, for example, 0.1L/min, 1L/min, 3L/min, 5L/min, 8L/min, 10L/min, 15L/min, 20L/min, 23L/min, 25L/min, 30L/min, 35L/min, 40L/min, 45L/min, 50L/min, 60L/min, 65L/min, 70L/min, 80L/min, 85L/min, 90L/min, 95L/min, 100L/min, or the like, preferably 5L/min to 50L/min.
Preferably, when the gaseous tin organometallic compound is introduced into the rotary kiln using a carrier gas, the flow rate of the mixed gas of the carrier gas and the gaseous tin organometallic compound is 0.1L/min to 100L/min, for example, 0.5L/min, 3L/min, 10L/min, 20L/min, 30L/min, 40L/min, 50L/min, 60L/min, 70L/min, 85L/min, 95L/min, 100L/min, etc., preferably 2L/min to 20L/min.
Preferably, the rotary kiln has a rotational speed of 0.1r/min to 10r/min, such as 0.1r/min, 0.5r/min, 1r/min, 2r/min, 3r/min, 4r/min, 5r/min, 6r/min, 7r/min, 8r/min or 10 r/min.
Preferably, the mass concentration of the reaction gas in the rotary furnace during the chemical vapor deposition is 60% or more, for example, 60%, 62%, 65%, 67.5%, 70%, 73%, 75%, 77%, 80%, 82%, 85%, or 90%.
Preferably, the temperature of the chemical vapor deposition is 300 ℃ to 1000 ℃, such as 300 ℃, 400 ℃, 450 ℃, 500 ℃, 600 ℃, 625 ℃, 650 ℃, 700 ℃, 750 ℃, 800 ℃, 850 ℃, 900 ℃, 950 ℃, or 1000 ℃, and the like.
Preferably, the time of the chemical vapor deposition is 5min to 600min, such as 5min, 30min, 45min, 60min, 90min, 120min, 150min, 180min, 210min, 240min, 260min, 270min, 300min, 320min, 350min, 380min, 400min, 420min, 450min, 480min, 500min, 520min, 550min, 570min, 600min, and the like.
The preparation method of the composite cathode material provided by the second aspect and the third aspect of the invention can enable the conductive film to be uniformly coated on the surface of the cathode material, and can realize complete coating.
In a fourth aspect, the present invention provides a positive electrode, wherein the raw material components of the positive electrode comprise the composite positive electrode material according to the first aspect.
In a fifth aspect, the present invention provides a lithium ion battery comprising the composite cathode material according to the first aspect.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the invention, the composite anode material is prepared by coating the ITO film on the surface of the anode material, the coated ITO film has strong conductivity, and the resistivity of the ITO conductive film is 10-3Ω·cm～10-5Omega cm is close to the resistivity of metal, and the material completely wraps the surface of the material, so that the direct contact between the electrolyte and the anode material can be prevented, the occurrence of side reactions can be reduced, the charging and discharging performance, the rate capability, the cycle performance and the safety performance of the battery under the condition of large flow can be improved, and the material can be applied to the field of 3C lithium ion batteries and power batteries. Compared with a battery made of the anode material without a conductive film, the composite anode material has the advantages that the 5C rate performance is improved by 15-28 percent, the capacity retention rate is improved by 7-11 percent after 50 cycles, the heat release temperature is improved by 7-11 percent, and the composite anode material is made into an anode and assembled into the batteryThe safety performance is improved at 20-30 ℃.
(2) The invention provides a method for preparing a composite anode material by respectively adopting spray pyrolysis and chemical vapor deposition, both the two methods can realize uniform and complete coating of a conductive film on the surface of the anode material, have good associativity and solve the problems that the coating of the existing anode material is not uniform and a coating object can not be completely coated on the surface of the material. The method of the invention is simple to operate and easy for industrial production.
Drawings
FIG. 1 shows LiNi, a positive electrode material in example 30.8Co0.15Al0.05O2And (4) a TEM image of the composite cathode material obtained after coating the ITO conductive film.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
And (3) testing the conductivity:
the composite positive electrode materials of examples 1 to 8 and the positive electrode materials of comparative examples 1 to 3 were subjected to conductivity tests, and 3g to 5g of the above-mentioned samples were weighed and tested for conductivity using a powder conductivity meter.
Assembling the battery:
the composite positive electrode materials of examples 1 to 8 and the positive electrode materials of comparative examples 1 to 3 were used as positive electrode materials, and slurry-mixed and coated on an aluminum foil as a positive electrode and a lithium sheet as a negative electrode according to a mass ratio of the positive electrode material to a conductive agent to a binder of 90:5:5, thereby assembling a simulated battery.
And (3) rate performance test:
testing discharge performance with different multiplying powers, and testing conditions are as follows: the voltage is 3.0V-4.3V, 0.5C charge/0.5C discharge, 0.5C charge/1.0C discharge, 0.5C charge/2.0C discharge, 0.5C charge/5.0C discharge. The test results are shown in Table 1.
And (3) testing the cycle performance:
the composite positive electrode materials of examples 1 to 8 and the positive electrode materials of comparative examples 1 to 3 were used as positive electrode materials, and slurry-mixed and coated on aluminum foil as a positive electrode and a lithium sheet as a negative electrode according to a mass ratio of the positive electrode material, a conductive agent and a binder of 96:2:2, to assemble a button cell. The charge and discharge cycle performance test is carried out under the conditions of 0.5C/1.0C and 3.0-4.2V.
And (4) safety performance testing:
disassembling the battery after the first full charge in a drying room, taking down the positive plate, soaking and cleaning the battery for 30min by using DMC, and performing DSC test after drying, wherein the DSC test conditions are as follows: n is a radical of2The exothermic peak temperature was measured in the atmosphere at a ramp rate of 10 ℃/min from 40 ℃ to 400 ℃.
Example 1
Preparing a composite cathode material:
(1) 7.82g of In (NO) were weighed out separately3)3·5H2O and 0.58g SnCl4·5H2Dissolving O in 1000ml of methanol solution, and stirring at the stirring speed of 200r/min for 60min to prepare ITO precursor solution;
(2) 500g of a positive electrode material LiNi was added to the above solution under stirring1/3Co1/3Mn1/3O2Adding a thickening agent FR400 after continuously stirring for 30min, adjusting the viscosity of the slurry until the anode material does not settle, spraying under the condition of stirring the dispersion liquid, wherein the carrier gas of spraying is compressed air, and the carrier gas pressure is 5kg/m2The flow rate of the dispersion liquid is 100ml/min, the spraying temperature is 200 ℃, the anode material coated with the ITO precursor film on the surface is obtained, then the anode material is pyrolyzed for 8 hours at 700 ℃, cooled and sieved, and the composite anode material is obtained, wherein the composite anode material is composed of the anode material and an ITO conductive film coated on the surface of the anode material, and the thickness of the ITO conductive film is about 20 nm.
The conductivity of the composite cathode material of the embodiment is 6.51S/cm through a conductivity test.
The rate performance test is shown in table 1.
The first specific discharge capacity of the battery prepared by adopting the composite cathode material of the embodiment as the cathode material and assembling the cathode material is 155mAh/g, and the first efficiency is 89.2%.
Through cycle performance test, the capacity retention rate is 99.1 percent after 50 cycles, and the cycle performance is higher than that of the LiNi which is not coated1/ 3Co1/3Mn1/3O2The retention rate is improved from 92.6 percent to 99.1 percent,the cycle performance is obviously improved by 7 percent.
The safety performance test shows that the ITO-coated composite positive electrode material has the heat release temperature of 256.7 ℃, the peak temperature of 278.3 ℃ and the heat release finishing temperature of 296.8 ℃, which shows that the ITO-coated composite positive electrode material has the heat release temperature (the heat release starting temperature of 221.9 ℃, the peak temperature of 241.3 ℃ and the heat release finishing temperature of 258.8 ℃) higher than that of the uncoated positive electrode material, so that the safety performance of the material is improved.
Example 2
Preparing a composite cathode material:
(1) 7.82g of In (NO) were weighed out separately3)3·5H2O and 0.58g SnCl4·5H2Dissolving O in 1000ml of methanol solution, and stirring at the stirring speed of 200r/min for 60min to prepare ITO precursor solution;
(2) 500g of a positive electrode material LiNi was added to the above solution under stirring0.6Co0.2Mn0.2O2Adding a thickening agent FR400 after continuously stirring for 30min, adjusting the viscosity of the slurry until the anode material does not settle, spraying under the condition of stirring the dispersion liquid, wherein the carrier gas of spraying is compressed air, and the carrier gas pressure is 5kg/m2The flow rate of the dispersion liquid is 100ml/min, the spraying temperature is 200 ℃, the anode material coated with the ITO precursor film on the surface is obtained, then the anode material is pyrolyzed for 6 hours at 600 ℃, cooled and sieved, and the composite anode material is obtained, wherein the composite anode material is composed of the anode material and an ITO conductive film coated on the surface of the anode material, and the thickness of the ITO conductive film is about 32 nm.
The conductivity of the composite cathode material of the embodiment is 9.36S/cm through a conductivity test.
The rate performance test is shown in table 1.
The first specific discharge capacity of the battery prepared by adopting the composite cathode material of the embodiment as the cathode material and assembling the cathode material is 185mAh/g, and the first efficiency is 90.2%.
Through cycle performance test, the capacity retention rate is 98.6 percent after 50 cycles, and the cycle performance is higher than that of the LiNi which is not coated0.6Co0.2Mn0.2O2The retention rate is improved from 90.1 percent to98.6 percent, the cycle performance is obviously improved by 9 percent.
The safety performance test shows that the ITO-coated composite positive electrode material has the heat release temperature (the heat release starting temperature is 213.7 ℃, the peak temperature is 230.1 ℃ and the heat release finishing temperature is 241.2 ℃) higher than that of an uncoated positive electrode material, and further improves the safety performance of the material, wherein the heat release starting temperature is 241.4 ℃, the peak temperature is 259.3 ℃ and the heat release finishing temperature is 281.2 ℃.
Example 3
Preparing a composite cathode material:
(1) 5.86g of InCl were weighed out separately3·4H2O and 0.37g SnCl2·2H2Dissolving O in 1000ml ethanol solution, stirring for 60min at the stirring speed of 200r/min, and preparing ITO precursor solution;
(2) 1000g of positive electrode material LiNi was added to the above solution under stirring0.8Co0.15Al0.05O2Adding a thickening agent FR400 after continuously stirring for 30min, adjusting the viscosity of the slurry until the anode material does not settle, spraying under the condition of stirring the dispersion liquid, wherein the carrier gas of spraying is compressed air, and the carrier gas pressure is 5kg/m2The flow rate of the dispersion liquid is 80ml/min, the spraying temperature is 150 ℃, the anode material coated with the ITO precursor film on the surface is obtained, then the anode material is pyrolyzed for 6 hours at 600 ℃, cooled and sieved, and the composite anode material is obtained, wherein the composite anode material is composed of the anode material and the ITO conductive film coated on the surface of the anode material, and the thickness of the ITO conductive film is 45 nm.
The conductivity of the composite cathode material of the embodiment is 0.67 × 10 by conducting property test2S/cm。
FIG. 1 shows LiNi, a positive electrode material in example 30.8Co0.15Al0.05O2As can be seen from the TEM image of the composite positive electrode material obtained after coating the ITO conductive film, the thickness of the ITO conductive film was 45 nm.
The rate performance test is shown in table 1.
The first specific discharge capacity of the battery prepared by adopting the composite cathode material of the embodiment as the cathode material and assembling the cathode material is 202mAh/g, and the first efficiency is 91.5%.
Through cycle performance test, the capacity retention rate is 98.8 percent after 50 cycles, and the cycle performance is higher than that of LiNi which is not coated0.8Co0.15Al0.05O2The retention rate is improved from 89.2% to 98.8%, the cycle performance is obviously improved, and the improvement percentage is 10%.
Through safety performance tests, the heat release starting temperature is 228.6 ℃, the peak temperature is 245.8 ℃ and the heat release finishing temperature is 258.4 ℃, which shows that the ITO-coated composite positive electrode material has a higher heat release temperature (the heat release starting temperature is 208.1 ℃, the peak temperature is 218.0 ℃ and the heat release finishing temperature is 236.7 ℃) than that of an uncoated positive electrode material, and further the safety performance of the material is improved.
Example 4
Preparing a composite cathode material:
(1) respectively weighing 6.19g of indium acetate and 0.33g of tin sulfate, dissolving in 2000ml of ethanol solution, and stirring at a stirring speed of 350r/min for 120min to prepare an ITO precursor solution;
(2) 3000g of a positive electrode material LiNi was added to the above solution under stirring0.8Co0.15Al0.05O2Adding a thickening agent FR400 after continuously stirring for 30min, adjusting the viscosity of the slurry until the anode material does not settle, spraying under the condition of stirring the dispersion liquid, wherein the carrier gas of spraying is compressed air, and the carrier gas pressure is 8kg/m2The flow rate of the dispersion liquid is 150ml/min, the spraying temperature is 200 ℃, the anode material coated with the ITO precursor film on the surface is obtained, then the anode material is pyrolyzed at 500 ℃ for 12 hours, cooled and sieved, and the composite anode material is obtained, wherein the composite anode material is composed of the anode material and an ITO conductive film coated on the surface of the anode material, and the thickness of the ITO conductive film is about 52 nm.
The conductivity of the composite cathode material of the embodiment is 0.22 × 10 by conducting property test2S/cm。
The rate performance test is shown in table 1.
The first specific discharge capacity of the battery prepared by taking the composite cathode material of the embodiment as the cathode material and assembling the cathode material is 203.7mAh/g, and the first efficiency is 91.9%.
Through cycle performance test, the capacity retention rate is 99.0 percent after 50 cycles, and the cycle performance is higher than that of the LiNi which is not coated0.8Co0.15Al0.05O2The retention rate is improved from 89.2% to 99.0%, the cycle performance is obviously improved, and the improvement percentage is 11%.
The safety performance test shows that the ITO-coated composite positive electrode material has the heat release temperature of 231.3 ℃, the peak temperature of 249.0 ℃ and the heat release finishing temperature of 262.1 ℃, compared with the uncoated positive electrode material (the heat release starting temperature of 208.1 ℃, the peak temperature of 218.0 ℃ and the heat release finishing temperature of 236.7 ℃), and further improves the safety performance of the material.
Example 5
Firstly, the positive electrode material LiNi is used1/3Co1/3Mn1/3O2Placing in a rotary furnace, heating at 5 deg.C/min while heating at 2.0m3Introducing oxygen into the rotary furnace at a speed of 5r/min at a speed of/h, placing the trimethyl indium in a container at 300 ℃, and vaporizing to obtain trimethyl indium vapor; putting tin tetrachloride into a container at 250 ℃, vaporizing to obtain tin tetrachloride steam, introducing the generated trimethyl indium steam and the generated tin tetrachloride steam into a rotary furnace by using carrier gas nitrogen, carrying out chemical vapor deposition at 700 ℃ for 30min at a flow rate of a mixed gas of the trimethyl indium steam and the carrier gas of 20L/min and a flow rate of a mixed gas of the tin tetrachloride steam and the carrier gas of 5L/min, and cooling to room temperature to obtain the composite anode material, wherein the composite anode material is composed of an anode material and an ITO conductive film coated on the surface of the anode material, and the thickness of the ITO conductive film is about 38 nm.
The conductivity of the composite cathode material of the embodiment is 1.07 multiplied by 10S/cm after being tested by a conductivity test.
The rate performance test is shown in table 1.
The first specific discharge capacity of the battery prepared by adopting the composite cathode material of the embodiment as the cathode material and assembling the cathode material is 158.3mAh/g, and the first efficiency is 89.5%.
Through cycle performance test, the capacity retention rate is 99.8 percent after 50 cycles, and the cycle performance is higher than that of the LiNi which is not coated1/ 3Co1/3Mn1/3O2The retention rate is improved from 89.8% to 99.8%, the cycle performance is obviously improved, and the improvement percentage is 11%.
The safety performance test shows that the heat release starting temperature is 260.4 ℃, the peak temperature is 282.9 ℃ and the heat release finishing temperature is 300.8 ℃, which shows that the ITO-coated composite anode material has higher heat release temperature (the heat release starting temperature is 221.9 ℃, the peak temperature is 241.3 ℃ and the heat release finishing temperature is 258.8 ℃) than the uncoated anode material, and further improves the safety performance of the material.
Example 6
Firstly, the positive electrode material LiNi is used0.6Co0.2Mn0.2O2Placing in a rotary furnace, heating at 5 deg.C/min while heating at 1.0m3Introducing oxygen into the rotary furnace at a speed of 5r/min, placing the acetylacetone indium in a container at 500 ℃, and vaporizing to obtain acetylacetone indium vapor; putting tetramethyltin in a container at 200 ℃, vaporizing to obtain tetramethyltin steam, introducing the generated acetylacetone indium steam and tetramethyltin steam into a rotary furnace by using carrier gas nitrogen, carrying out chemical vapor deposition at 500 ℃ for 60min at a flow rate of a mixed gas of the acetylacetone indium steam and the carrier gas of 30L/min and a flow rate of a mixed gas of the tetramethyltin steam and the carrier gas of 10L/min, and cooling to room temperature to obtain the composite anode material, wherein the composite anode material is composed of an anode material and an ITO conductive film coated on the surface of the anode material, and the thickness of the ITO conductive film is about 55 nm. .
The conductivity of the composite cathode material of the embodiment is 3.89 multiplied by 10S/cm after being tested by the conductivity performance.
The rate performance test is shown in table 1.
The first specific discharge capacity of the battery prepared by adopting the composite cathode material of the embodiment as the cathode material and assembling the cathode material is 182.1mAh/g, and the first efficiency is 90.5%.
Through cycle performance test, the capacity retention rate is 99.3 percent after 50 cycles, and the cycle performance is higher than that of the LiNi which is not coated0.6Co0.2Mn0.2O2The retention rate is improved from 90.1 percent to 99.3 percent, the cycle performance is obviously improved, and the improvement percentageThe ratio is 10%.
Through safety performance tests, the heat release starting temperature is 247.5 ℃, the peak temperature is 264.1 ℃ and the heat release finishing temperature is 291.5 ℃, which shows that the ITO-coated composite anode material has higher heat release temperature (the heat release starting temperature is 213.7 ℃, the peak temperature is 230.1 ℃ and the heat release finishing temperature is 241.2 ℃) than that of an uncoated anode material, and further improves the safety performance of the material.
Example 7
Firstly, the positive electrode material LiNi is used0.8Co0.15Al0.05O2Placing in a rotary furnace, heating at 5 deg.C/min while heating at 1.0m3Introducing oxygen into the rotary furnace at a speed of 5r/min at a speed of/h, placing the trimethyl indium in a container at 300 ℃, and vaporizing to obtain trimethyl indium vapor; putting tin tetrachloride into a container at 250 ℃, vaporizing to obtain tin tetrachloride steam, introducing the generated trimethyl indium steam and the generated tin tetrachloride steam into a rotary furnace by using carrier gas nitrogen, carrying out chemical vapor deposition at 600 ℃ for 30min at a flow rate of a mixed gas of the trimethyl indium steam and the carrier gas of 20L/min and a flow rate of a mixed gas of the tin tetrachloride steam and the carrier gas of 10L/min, and then cooling to room temperature to obtain the composite anode material, wherein the composite anode material is composed of an anode material and an ITO conductive film coated on the surface of the anode material, and the thickness of the ITO conductive film is about 70 nm.
The conductivity of the composite cathode material of the embodiment is 7.59 multiplied by 10 after being tested by the conductivity test2S/cm。
The rate performance test is shown in table 1.
The first specific discharge capacity of the battery prepared by taking the composite cathode material of the embodiment as the cathode material and assembling the cathode material is 203.7mAh/g, and the first efficiency is 91.1%.
Through cycle performance test, the capacity retention rate is 99.2 percent after 50 cycles, and the cycle performance is higher than that of the LiNi which is not coated0.8Co0.15Al0.05O2The retention rate is improved from 89.2% to 99.2%, the cycle performance is obviously improved, and the improvement percentage is 11%.
Through safety performance tests, the heat release starting temperature is 232.7 ℃, the peak temperature is 251.6 ℃ and the heat release finishing temperature is 279.8 ℃, which shows that the ITO-coated composite cathode material has higher heat release temperature (the heat release starting temperature is 208.1 ℃, the peak temperature is 218.0 ℃ and the heat release finishing temperature is 236.7 ℃) than the uncoated cathode material, and further improves the safety performance of the material.
Example 8
Firstly, the positive electrode material LiNi is used0.8Co0.15Al0.05O2Placing in a rotary furnace, heating at 10 deg.C/min while heating at 1.5m3Introducing oxygen into the rotary furnace at a speed of 8r/min, putting indium diethylacetate into a 350 ℃ container, vaporizing to obtain indium diethylacetate steam, putting triphenyl tin into a 500 ℃ container, vaporizing to obtain triphenyl tin steam, introducing the generated indium diethylacetate steam and triphenyl tin steam into the rotary furnace through carrier gas argon, wherein the flow rate of the mixed gas of the indium diethylacetate steam and the carrier gas is 10L/min, the flow rate of the mixed gas of the triphenyl tin steam and the carrier gas is 2L/min, performing chemical vapor deposition at 700 ℃ for 100min, and cooling to room temperature to obtain the composite anode material, wherein the composite anode material is composed of an anode material and an ITO conductive film coated on the surface of the anode material, and the thickness of the ITO conductive film is about 92 nm.
The conductivity of the composite cathode material of the embodiment is 2.11 × 10 by conducting property test2S/cm。
The rate performance test is shown in table 1.
The first specific discharge capacity of the battery prepared by adopting the composite cathode material of the embodiment as the cathode material and assembling the cathode material is 204.8mAh/g, and the first efficiency is 91.8%.
Through cycle performance test, the capacity retention rate is 98.9 percent after 50 cycles, and the cycle performance is higher than that of the LiNi which is not coated0.8Co0.15Al0.05O2The retention rate is improved from 89.2% to 98.9%, the cycle performance is obviously improved, and the improvement percentage is 11%.
The safety performance test shows that the ITO-coated composite positive electrode material has the heat release temperature of 229.1 ℃, the peak temperature of 250.3 ℃ and the heat release finishing temperature of 281.1 ℃, which shows that the ITO-coated composite positive electrode material has the heat release temperature (the heat release starting temperature of 208.1 ℃, the peak temperature of 218.0 ℃ and the heat release finishing temperature of 236.7 ℃) higher than that of the uncoated positive electrode material, so that the safety performance of the material is improved.
Comparative example 1
The positive electrode material of this comparative example was LiNi which was not subjected to coating treatment1/3Co1/3Mn1/3O2。
The conductivity of the positive electrode material of the present example was 3.63 × 10 as measured by conductivity test-3S/cm。
The rate performance test is shown in table 1.
The first specific discharge capacity of the battery prepared by adopting the positive electrode material of the comparative example as the positive electrode material and assembling the positive electrode material is 158mAh/g, and the first efficiency is 89.8%.
Through a cycle performance test, the capacity retention rate is 92.6 percent after 50 cycles.
Through safety performance tests, the heat release starting temperature is 221.9 ℃, the peak temperature is 241.3 ℃, and the heat release finishing temperature is 258.8 ℃, which shows that the anode material without being coated starts to release heat at 221.9 ℃, so that the thermal stability is poor, and further the safety performance is poor.
Comparative example 2
The positive electrode material of this comparative example was LiNi which was not subjected to coating treatment0.6Co0.2Mn0.2O2。
The conductivity of the positive electrode material of this comparative example was 6.98 × 10 as measured by conductivity test-3S/cm。
The rate performance test is shown in table 1.
The first specific discharge capacity of the battery prepared by adopting the positive electrode material of the comparative example as the positive electrode material and assembling the positive electrode material is 186.3mAh/g, and the first efficiency is 90.6%.
Through a cycle performance test, the capacity retention rate is 90.1 percent after 50 cycles.
Through safety performance tests, the heat release starting temperature is 213.7 ℃, the peak temperature is 230.1 ℃, and the heat release finishing temperature is 241.2 ℃, which shows that the anode material without being coated starts to release heat at 213.7 ℃, so that the thermal stability is poor, and further the safety performance is poor.
Comparative example 3
The positive electrode material of this comparative example was LiNi which was not subjected to coating treatment0.8Co0.15Al0.05O2。
The conductivity of the positive electrode material of this comparative example was 1.41 × 10 as measured by conductivity test-1S/cm。
The rate performance test is shown in table 1.
The first specific discharge capacity of the battery prepared by adopting the positive electrode material of the comparative example as the positive electrode material and assembling the positive electrode material is 204.5mAh/g, and the first efficiency is 92.1%.
Through a cycle performance test, the capacity retention rate is 89.2 percent after 50 cycles.
Through safety performance tests, the heat release starting temperature is 208.1 ℃, the peak temperature is 218.0 ℃, and the heat release finishing temperature is 236.7 ℃, which shows that the anode material without being coated starts to release heat at 208.1 ℃, so that the thermal stability is poor, and further the safety performance is poor.
TABLE 1 multiplying power Performance Table
Figure BDA0001235982850000221
As can be seen from Table 1, examples 1 and 5 are directed to LiNi1/3Co1/3Mn1/3O2After the conductive film is coated, the multiplying power performance is obviously improved, and the 0.5C charging/1.0C discharging multiplying power performance can be improved to 98.9% from 97.2%; the 0.5C charge/2.0C discharge rate performance can be improved from 93.1 percent to 97.7 percent; the 0.5C charge/5.0C discharge rate performance can be improved from 83.8 percent to 96.2 percent, and the improvement percentage reaches 15 percent.
Examples 2 and 6 on LiNi0.6Co0.2Mn0.2O2After the conductive film is coated, the multiplying power performance is obviously improved, and the multiplying power performance of 0.5C charge/1.0C discharge can be improved to 98.2% from 96.9%; the 0.5C charge/2.0C discharge rate performance can be improved from 91.9 percent to 97.0 percent; the 0.5C charge/5.0C discharge rate performance can be improved from 80.3% to 95.8%, and the improvement percentage reaches 19%.
Examples 3 to 4 and examples 7 to 8 on LiNi0.8Co0.15Al0.05O2After the conductive film is coated, the multiplying power performance is obviously improved, and the multiplying power performance of 0.5C charge/1.0C discharge can be improved to 99.3% from 94.6%; the 0.5C charge/2.0C discharge rate performance can be improved from 90.2 percent to 98.7 percent; the 0.5C charge/5.0C discharge rate performance is improved from 75.1% to 96.0%, and the improvement percentage reaches 28%.
The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims (39)

1. The composite anode material is characterized by comprising an anode material and a conductive film coated on the surface of the anode material, wherein the mass ratio of the anode material to the conductive film In the composite anode material is 1 (0.001-0.1), the conductive film comprises Indium Tin Oxide (ITO) which is tin-doped indium oxide, and the indium tin oxide is In2O3And SnO2The composition consists of 1 and 3-10 mass ratios;
the composite cathode material is prepared by adopting the following method, and the preparation method comprises the following steps:
(1) preparing a precursor solution of the conductive film;
(2) adding a positive electrode material into the conductive film precursor solution obtained in the step (1) to obtain slurry, and adding a thickening agent to adjust the viscosity of the slurry to obtain dispersion liquid;
(3) carrying out spray thermal decomposition on the dispersion liquid obtained in the step (2), and coating a conductive film on the surface of the positive electrode material to obtain a composite positive electrode material;
wherein the mass ratio of the conducting film precursor solution in the step (2) to the thickening agent is 1 (0.0001-0.1);
when the spray thermal decomposition is carried out in the step (3), the spray temperature is 100-300 ℃, and the pyrolysis temperature is 300-800 ℃;
or
Placing the anode material in a rotary furnace, heating, and introducing oxygen at the oxygen introduction rate of 1m3/h～5m3Respectively introducing the gaseous indium metal organic compound and the gaseous tin metal organic compound into a rotary furnace by using carrier gas, carrying out chemical vapor deposition, and coating an indium tin oxide conductive film on the surface of the anode material to obtain a composite anode material;
wherein the mass concentration of the oxygen in the rotary furnace is more than 60%, the temperature of the chemical vapor deposition is 600-1000 ℃, and the time of the chemical vapor deposition is 5-600 min.
2. The composite positive electrode material according to claim 1, wherein the positive electrode material has a chemical composition of LiNixCoyMzO2And/or LiFePO4Wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and z is more than or equal to 0 and less than or equal to 1<1, and x + y + z is 1, and M is selected from any one or a combination of at least two of Mn, Al, Mg, Zr, Zn, Cu or Cr.
3. The composite positive electrode material according to claim 1, wherein the thickness of the conductive film is on the order of nanometers.
4. The composite positive electrode material according to claim 1, wherein the conductive film has a thickness of 0.5nm to 200 nm.
5. The composite positive electrode material according to claim 1, wherein the In2O3And SnO2The mass ratio of (A) to (B) is 9: 1.
6. The method for preparing a composite positive electrode material according to any one of claims 1 to 5, characterized in that the method comprises the steps of:
(1) preparing a precursor solution of the conductive film;
(2) adding a positive electrode material into the conductive film precursor solution obtained in the step (1) to obtain slurry, and adding a thickening agent to adjust the viscosity of the slurry to obtain dispersion liquid;
(3) carrying out spray thermal decomposition on the dispersion liquid obtained in the step (2), and coating a conductive film on the surface of the positive electrode material to obtain a composite positive electrode material;
wherein the mass ratio of the conducting film precursor solution in the step (2) to the thickening agent is 1 (0.0001-0.1);
when the spray thermal decomposition is carried out in the step (3), the spray temperature is 100-300 ℃, and the pyrolysis temperature is 300-800 ℃.
7. The method according to claim 6, wherein the conductive film precursor solution in step (1) is an indium tin oxide precursor solution.
8. The method of claim 7, wherein the indium tin oxide precursor solution is prepared by: dissolving indium-based material and tin-based material in solvent, and stirring to obtain indium tin oxide precursor solution.
9. The method of claim 8 wherein the indium-based material is any one of indium nitrate, indium chloride, indium sulfate, indium acetate, or indium oxalate, or a combination of at least two thereof.
10. The method of claim 8, wherein the tin-based material is any one of tin nitrate, tin chloride, tin sulfate, tin acetate, or stannous oxalate, or a combination of at least two thereof.
11. The method of claim 8 wherein the molar ratio of indium-based material to tin-based material is (1-20): 1.
12. The method according to claim 8, wherein the solvent is any one of methanol, ethanol, benzyl alcohol or ethylene glycol or a combination of at least two of them.
13. The method of claim 8, wherein the stirring speed is 50r/min to 500 r/min.
14. The method according to claim 8, wherein the stirring time is 30min to 300 min.
15. The method according to claim 6, wherein the chemical composition of the cathode material of step (2) is LiNixCoyMzO2Wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and z is more than or equal to 0 and less than or equal to 1<1, and x + y + z is 1, and M is selected from any one or a combination of at least two of Mn, Al, Mg, Zr, Zn, Cu or Cr.
16. The method according to claim 6, wherein the step (2) of adding the positive electrode material is accompanied by stirring.
17. The method according to claim 16, wherein the stirring is continued for 10min to 120min after the positive electrode material is added in the step (2).
18. The method according to claim 17, wherein the stirring is continued for 30min after the cathode material is added in step (2).
19. The method according to claim 6, wherein the solid content of the slurry in the step (2) is 20-60 wt%.
20. The method according to claim 6, wherein the thickener of step (2) is a solid alcohol thickener FR 400.
21. The method of claim 6, wherein the dispersion is continuously stirred while the spray pyrolysis is performed in step (3).
22. The method of claim 6, wherein the carrier gas for spraying in the thermal decomposition of the spray in step (3) is compressed air.
23. The method according to claim 6, wherein the spray pyrolysis in the step (3) is carried out under a carrier gas pressure of 3kg/m2～10kg/m2。
24. The method according to claim 6, wherein the spray pyrolysis in the step (3) is carried out at a dispersion flow rate of 5ml/min to 500 ml/min.
25. The method of claim 6, wherein the pyrolysis time in the spray pyrolysis in step (3) is 2 to 20 hours.
26. The preparation method of the composite cathode material according to any one of claims 1 to 4, wherein the surface of the cathode material is coated with the indium tin oxide conductive film by a chemical vapor deposition method, and the method comprises the following steps:
placing the anode material in a rotary furnace, heating, and introducing oxygen at the oxygen introduction rate of 1m3/h～5m3Respectively introducing the gaseous indium metal organic compound and the gaseous tin metal organic compound into a rotary furnace by using carrier gas, carrying out chemical vapor deposition, and coating an indium tin oxide conductive film on the surface of the anode material to obtain a composite anode material;
wherein the mass concentration of the oxygen in the rotary furnace is more than 60%, the temperature of the chemical vapor deposition is 600-1000 ℃, and the time of the chemical vapor deposition is 5-600 min.
27. The method of claim 26, wherein the indium metal organic compound is any one of or a combination of at least two of indium acetylacetonate, trimethyl indium, triethyl indium, triphenyl indium, or indium diethyl acetate.
28. The method of claim 26, wherein the tin metal organic compound has a chemical composition RxSnY, wherein R is any one or combination of alkyl or aryl, Y is halogen, and x is an integer of 0-4.
29. The method of claim 26, wherein the tin metal organic compound is any one of trimethyl tin, tetramethyl tin, triethyl tin, triphenyl tin, or tin tetrachloride, or a combination of at least two thereof.
30. The method of claim 26, wherein the positive electrode material has a chemical composition of LiNixCoyMzO2Wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and z is more than or equal to 0 and less than or equal to 1<1, and x + y + z is 1, and M is selected from any one or a combination of at least two of Mn, Al, Mg, Zr, Zn, Cu or Cr.
31. The method according to claim 26, wherein the heating is performed at a temperature increase rate of 0.5 ℃/min to 15 ℃/min.
32. The method of claim 26, wherein the carrier gas is any one of nitrogen, helium, neon, argon, krypton, or xenon, or a combination of at least two thereof.
33. The method of claim 26, wherein the flow rate of the mixed gas of the carrier gas and the gaseous indium metal organic compound is 0.1L/min to 100L/min when the gaseous indium metal organic compound is introduced into the rotary kiln using the carrier gas.
34. The method of claim 33, wherein the flow rate of the mixed gas of the carrier gas and the gaseous indium metal organic compound is 5L/min to 50L/min when the gaseous indium metal organic compound is introduced into the rotary kiln using the carrier gas.
35. The method of claim 26, wherein the flow rate of the mixed gas of the carrier gas and the gaseous tin organometallic compound is 0.1L/min to 100L/min when the gaseous tin organometallic compound is introduced into the rotary kiln using the carrier gas.
36. The method of claim 35, wherein the flow rate of the mixed gas of the carrier gas and the gaseous tin organometallic compound is 2L/min to 20L/min when the gaseous tin organometallic compound is introduced into the rotary kiln using the carrier gas.
37. The method of claim 26, wherein the rotary kiln is rotated at a speed of 0.1r/min to 10 r/min.
38. A positive electrode characterized by comprising the composite positive electrode material according to any one of claims 1 to 5 as a raw material component.
39. A lithium ion battery comprising the positive electrode material according to any one of claims 1 to 5.
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