CN105845909B - Lithium ion battery positive electrode active material, preparation method thereof and lithium ion battery - Google Patents

Lithium ion battery positive electrode active material, preparation method thereof and lithium ion battery Download PDF

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CN105845909B
CN105845909B CN201610268679.1A CN201610268679A CN105845909B CN 105845909 B CN105845909 B CN 105845909B CN 201610268679 A CN201610268679 A CN 201610268679A CN 105845909 B CN105845909 B CN 105845909B
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lithium ion
ion battery
precursor
active material
lic
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CN105845909A (en
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尚伟丽
孔令涌
方东升
李佳佳
黄少真
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Qujing Defang Nano Technology Co.,Ltd.
SHENZHEN DYNANONIC Co.,Ltd.
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Qujing Defang Nano Technology Co ltd
Shenzhen Dynanonic 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
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—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
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • 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
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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    • 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
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E60/10—Energy storage using batteries

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Abstract

The invention provides a lithium ion battery anode active material, the chemical expression of which is (A)1‑x·(LiC6)x，0<x<1, A is LiM1PO4、LiM2O2And LiM3 2O4At least one of (1), M1、M2Or M3Is selected from at least one of iron, cobalt, manganese, nickel, aluminum and vanadium. The lithium ion battery anode active material provided by the invention has higher capacity. The invention also provides a preparation method of the lithium ion battery anode active material, which comprises the following steps: separately providing A precursor and LiC6A precursor; pre-burning the precursor A in protective gas or air at a constant temperature of 200-500 ℃ for 1-5h, and naturally cooling to room temperature to obtain the pre-burned precursor A; pre-burning the A precursor and LiC6Uniformly mixing the precursors according to the molar ratio of 1-x: x to obtain a precursor of the lithium ion battery anode active material, and sintering the precursor of the lithium ion battery anode active material in a protective gas at the constant temperature of 300-700 ℃ for 5min-2h to obtain the lithium ion battery anode active material. The preparation method is unique and effective.

Description

Lithium ion battery positive electrode active material, preparation method thereof and lithium ion battery
Technical Field
The invention relates to the field of lithium ion batteries, in particular to a lithium ion battery anode active material, a preparation method thereof and a lithium ion battery.
Background
With the increasing demand of portable electronic devices and electric vehicles for lithium ion battery energy density, the research and development of lithium ion battery materials with high energy density are becoming more and more important.
Currently, commonly used lithium ion battery positive electrode materials include lithium cobaltate (LiCoO)2) Lithium manganate (LiMn)2O4) And lithium iron phosphate (LiFePO)4) And the actual specific capacities of the three materials are less than 160mAh/g, and the lithium ion batteries made of the electrode materials have low energy density due to low capacity, so that the high capacity requirements of the batteries on the materials are difficult to meet. Therefore, it is necessary to provide a positive electrode active material for a lithium ion battery having a high capacity.
Disclosure of Invention
In order to solve the problems, the invention provides a positive electrode active material of a lithium ion battery. The lithium ion battery anode active material is prepared from the conventional commonly used anode active material and LiC6Formed by compounding, LiC6The capacity of the anode is higher, and the capacity of the commonly used anode active material is greatly improved. The invention also provides a preparation method of the lithium ion battery anode active material, and the preparation method is unique and effective.
Hair brushIn a first aspect, a lithium ion battery positive active material is provided, wherein the chemical expression of the lithium ion battery positive active material is (A)1-x·(LiC6)xWherein, 0<x<1, A is LiM1PO4、LiM2O2And LiM3 2O4At least one of (1), M1、M2Or M3Is selected from at least one of iron, cobalt, manganese, nickel, aluminum and vanadium.
Wherein the value range of x is more than or equal to 0.05 and less than or equal to 0.4.
Wherein the surface of the A is coated with a first carbon layer or the LiC6Or the surface of the A is coated with a first carbon layer while the LiC is coated with a second carbon layer6Is coated with a second carbon layer.
Wherein, when the surface of the A is coated with a first carbon layer, the surface of the first carbon layer and the LiC6The surface of (a) is further coated with a third carbon layer, and the third carbon layer simultaneously contains the LiC6And A coated with the first carbon layer;
when the LiC is6When the surface of (a) is coated with the second carbon layer, the surface of (a) and the surface of the second carbon layer are further coated with a third carbon layer, and the third carbon layer simultaneously contains (a) and LiC having the surface coated with the second carbon layer6；
Coating the surface of the A with a first carbon layer while the LiC6When the surface of the carbon layer is coated with the second carbon layer, the surface of the first carbon layer and the surface of the second carbon layer are further coated with a third carbon layer, and the third carbon layer simultaneously comprises a coated with the first carbon layer and LiC coated with the second carbon layer6。
The lithium ion battery anode active material provided by the first aspect of the invention has high capacity, and in addition, the lithium ion battery anode active material has good stability and good conductivity.
The invention provides a preparation method of a lithium ion battery anode active material, which comprises the following steps:
providing a precursor A; a is LiM1PO4、LiM2O2And LiM3 2O4At least one of (1), M1、M2Or M3At least one of iron, cobalt, manganese, nickel, aluminum and vanadium is selected, the precursor A is presintered in protective gas or air at a constant temperature of 200-500 ℃ for 1-5h, and then is naturally cooled to room temperature, so as to obtain the presintered precursor A;
providing LiC6A precursor;
the pre-sintered A precursor and the LiC are mixed6Uniformly mixing the precursors according to the molar ratio of 1-x: x to obtain the precursor of the lithium ion battery anode active material, 0<x<1, then sintering the precursor of the lithium ion battery anode active material at the constant temperature of 300-700 ℃ for 5min-2h in protective gas to obtain the lithium ion battery anode active material, wherein the chemical formula of the lithium ion battery anode active material is (A)1-x·(LiC6)x，0<x<1。
The sintering operation of the precursor of the lithium ion battery positive electrode active material comprises the following specific steps: heating the precursor of the lithium ion battery anode active material to 400-600 ℃ at the heating rate of 1-5 ℃/min, sintering at constant temperature for 5-10min, and cooling to normal temperature at the cooling rate of 1-5 ℃/min.
Wherein, the LiC6The preparation method of the precursor comprises the following steps: an electrochemical cell is provided which uses C as a cathode, Li as an anode, and lithium hexafluorophosphate, tetraethylammonium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate (V), lithium trifluoromethanesulfonate, a dry solid polymer, a gel polymer or lithium bistrifluoromethylsulfonimide as an electrolyte, and a voltage of 0.5-2.5V is applied to the electrochemical cell in a protective gas to ionize the Li ionized from the anode+Depositing on a cathode C to obtain the LiC6And (3) precursor.
Wherein the cathode after deposition is dried at 40-100 ℃ under vacuum condition, and the LiC is obtained6Stripping the precursor from the cathode, and performing ball milling or sanding to obtain nanoscale LiC6And (3) precursor.
Wherein, LiC6Precursor bodyThe particle size of (A) is 10-80 nm.
The preparation method of the lithium ion battery anode active material provided by the second aspect of the embodiment of the invention is unique and effective, the prepared lithium ion battery anode active material has higher capacity, and in addition, the lithium ion battery anode active material has good stability and better conductivity.
In a third aspect, the invention provides a lithium ion battery, which comprises the lithium ion battery positive electrode active material provided by the first aspect of the invention.
The third aspect of the present invention provides a lithium ion battery having excellent discharge capacity.
Advantages of embodiments of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of embodiments of the invention.
Drawings
FIG. 1 is a graph of the cycle performance of a lithium ion battery prepared in example 1 of the present invention;
fig. 2 is a cycle performance diagram of the lithium ion battery prepared in example 1 of the present invention at different magnifications.
Detailed Description
While the following is a description of the preferred embodiments of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
The invention provides a lithium ion battery anode active material in a first aspect, wherein the chemical expression of the lithium ion battery anode active material is (A)1-x·(LiC6)xWherein, 0<x<1, A is LiM1PO4、LiM2O2And LiM3 2O4At least one of (1), M1、M2Or M3Is selected from at least one of iron, cobalt, manganese, nickel, aluminum and vanadium.
In the embodiment of the present invention, a is an existing commonly used positive electrode active material, and is not particularly limited.
In a preferred embodiment of the present invention, A is LiCoO2、LiMn2O4Or LiFePO4。
In the embodiment of the invention, x is more than or equal to 0.01 and less than or equal to 0.6.
In the embodiment of the invention, x is more than or equal to 0.05 and less than or equal to 0.4, and when x is more than or equal to 0.05 and less than or equal to 0.4, A and LiC are contained in the positive active material of the lithium ion battery6The positive active material has a proper proportion, and can have better stability and better electrochemical performance.
In the embodiment of the invention, x is more than or equal to 0.1 and less than or equal to 0.2.
In the embodiment of the invention, when A is LiM1PO4When the lithium ion battery anode active material is used, the particle size of the lithium ion battery anode active material is nano-scale or micron-scale, preferably 10-100nm, and the compaction density of the lithium ion battery anode active material is 2.3-2.5g/cm3. The capacity and the compaction density of the lithium ion battery anode active material are higher, so that the energy density of the battery is more favorably improved, and the application field of the battery prepared by the material is expanded.
In the embodiment of the invention, when A is LiM2O2Or LiM3 2O4When the particle size of the lithium ion battery anode active material is micron-sized, the particle size is preferably 1-1000 μm, and the compaction density of the lithium ion battery anode active material is 3.9-4.2g/cm3. The capacity and the compaction density of the lithium ion battery anode active material are higher, so that the energy density of the battery is more favorably improved, and the application field of the battery prepared by the material is expanded.
In the embodiment of the invention, the surface of A is coated with the first carbon layer or LiC6The surface of (A) is coated with a second carbon layer, or the surface of (A) is coated with a first carbon layer while LiC6Is coated with a second carbon layer. Here, the surface of A may or may not be coated with a carbon layer, LiC6The surface of the lithium ion battery anode active material can be coated with or without a carbon layer.
In the embodiment of the present invention, the surface of a may be coated with a carbon layer. Coating the surface of A with a carbon layer can improve the conductivity of A and prevent the agglomeration of A.
In a preferred embodiment of the present invention, LiC6May be coated with a carbon layer. In LiC6The surface of the carbon layer can improve LiC6Is used for the electrical conductivity of (1).
In a preferred embodiment of the present invention, the surface of the positive electrode active material of the lithium ion battery may be coated with a carbon layer. The carbon layer is coated on the surface of the lithium ion battery anode active material, so that the conductivity of the lithium ion battery anode active material can be improved, and the agglomeration of secondary particles of the lithium ion battery anode active material can be prevented.
In a preferred embodiment of the present invention, when A is LiM1PO4When the carbon coating is used, the surface of the A is coated with a first carbon layer. Due to LiM1PO4The conductive material is a semiconductor material, and in order to improve the conductive performance of the conductive material, the surface of the A is coated with a first carbon layer.
In a preferred embodiment of the present invention, when A is LiM2O2Or LiM3 2O4In this case, the surface of a may not be coated with the first carbon layer. Due to LiM2O2Or LiM3 2O4The conductive material is not coated with the first carbon layer, and the conductive performance is better.
In a preferred embodiment of the present invention, when A is LiM1PO4While the surface of A is coated with a first carbon layer, LiC6The surface of the first carbon layer and the surface of the second carbon layer are coated with a third carbon layer, and the third carbon layer simultaneously comprises LiM coated with the first carbon layer1PO4And LiC coated with a second carbon layer6. By so setting, LiM1PO4Is highly conductive, and LiC6After compounding, the LiM is not affected1PO4On the premise of conductivity of (2), the LiM is improved1PO4The capacity of (c).
In a preferred embodiment of the present invention, the carbon layer is made of at least one of artificial graphite, natural graphite, acetylene black, carbon black, mesocarbon microbeads, carbon nanotubes, carbon nanofibers, graphene, superconducting carbon black, and superconducting carbon fibers.
LiCoO2、LiMn2O4Or LiFePO4The capacity of the traditional battery positive electrode active material is low, the compaction density is low, and a battery with high energy density is difficult to obtain; conventional LiC6Has a capacity of 339mAh/g, and although the capacity is high, LiC6Has poor conductivity and stability, and cannot be used as a positive electrode active material alone. The invention relates to LiM1PO4、LiM2O2And LiM3 2O4And LiC6Compounding to obtain the new positive active material (A) of lithium ion battery1-x·(LiC6)x，LiC6Sufficient lithium is provided for the anode active material, so that the capacity of the anode active material of the lithium ion battery is greatly improved. In addition, the compaction density of the lithium ion battery anode active material is also greatly improved, so that the energy density of the lithium ion battery is improved. Meanwhile, the lithium ion battery anode active material has better stability and better conductivity, and the overall performance of the lithium ion battery anode active material obtained by the invention is superior to that of the single A battery anode active material and the single LiC6A battery positive electrode active material.
The lithium ion battery anode active material provided by the first aspect of the invention has high capacity, and in addition, the lithium ion battery anode active material has good stability and good conductivity.
The invention provides a preparation method of a lithium ion battery anode active material, which comprises the following steps:
providing a precursor A; a is LiM1PO4、LiM2O2And LiM3 2O4At least one of (1), M1、M2Or M3At least one of iron, cobalt, manganese, nickel, aluminum and vanadium is selected, the precursor A is presintered in protective gas or air at the constant temperature of 200-500 ℃ for 1-5h, and then the temperature is naturally reduced to room temperature, so as to obtain the presintered precursor A;
providing LiC6A precursor;
pre-burning the A precursor and LiC6Uniformly mixing the precursors according to the molar ratio of 1-x: x to obtain the precursor of the lithium ion battery anode active material, 0<x<1, then sintering the precursor of the lithium ion battery anode active material at the constant temperature of 300-700 ℃ for 5min-2h in protective gas to obtain the lithium ion battery anode active material, wherein the chemical formula of the lithium ion battery anode active material is (A)1-x·(LiC6)x，0<x<1。
In the embodiment of the present invention, the preparation method of the a precursor may be an existing common method, such as a high-temperature solid-phase reduction method, a sol-gel method, a hydrothermal method, or a microwave method.
In a preferred embodiment of the present invention, A is LiCoO2、LiMn2O4Or LiFePO4。
In a preferred embodiment of the present invention, LiFePO4The preparation method of the precursor comprises the following steps:
respectively dissolving a lithium source, an iron source and a phosphorus source into a solvent according to a molar ratio of 1:1:1 to obtain a mixed solution, heating the mixed solution to 40-60 ℃, reacting for 10-100min, and after the reaction is finished, performing spray drying on the mixed solution to obtain nano-scale LiFePO4And (3) precursor.
In a preferred embodiment of the present invention, the lithium source is at least one of lithium oxide, lithium hydroxide, lithium acetate, lithium carbonate, lithium nitrate, lithium nitrite, lithium phosphate, lithium dihydrogen phosphate, lithium oxalate, lithium molybdate, and lithium vanadate.
In a preferred embodiment of the present invention, the iron source is at least one of iron phosphate, ferrous acetate, ferrous pyrophosphate, ferrous carbonate, ferrous chloride, ferrous hydroxide, ferrous nitrate, ferrous oxalate, ferric chloride, ferric hydroxide, ferric nitrate, ferric citrate, and ferric oxide.
In a preferred embodiment of the present invention, the phosphorus source is at least one of phosphoric acid, diammonium phosphate, iron phosphate, and lithium dihydrogen phosphate.
In a preferred embodiment of the present invention, the solvent is at least one of water, ethanol, acetone, propanol, isopropanol, isobutanol, methanol, n-butanol, acetonitrile, tetrahydrofuran, diethyl ether, dichloromethane, chloroform, dimethyl sulfoxide and dimethylformamide.
In a preferred embodiment of the present invention, 1mol of LiH is added2PO4Dissolved in water to form LiH2PO4Solution, 1mol of simple substance iron is put into glacial acetic acid and then is mixed with LiH2PO4And mixing the solutions to obtain a mixed solution. Wherein the glacial acetic acid reacts with Fe to form ferrous acetate solution, and can also be used as iron ion compound and LiH2PO4The catalyst for the reaction for forming the lithium iron phosphate precursor is used. The preparation method of the mixed solution is simple and unique.
In a preferred embodiment of the present invention, the mixed solution is spray-dried in a protective gas at a temperature of 150-.
In a preferred embodiment of the present invention, the protective gas is at least one of nitrogen, argon and helium.
After providing a precursor A, presintering the precursor A in protective gas or air at the constant temperature of 200-500 ℃ for 1-5h, and naturally cooling to room temperature; forming lattice part in A precursor by pre-burning, forming semi-finished product, and then pre-burning A precursor and LiC6The precursor is continuously sintered, and the A precursor and the LiC can be sintered at the sintering temperature without being too high and the sintering time without being too long6The precursor is fully sintered, and LiC at high temperature is avoided6The precursor is volatilized, and the lithium ion battery anode active material with sufficient sintering and good crystal lattice is obtained.
In a preferred embodiment of the present invention, when A is LiM1PO4In the case of burning, the burning is performed in a protective gas. Pre-burning in a protective gas for the purpose of preventing LiM1PO4Oxidation of the sub-metal ions.
In a preferred embodiment of the present invention, the protective gas is at least one of nitrogen, argon and helium.
In a preferred embodiment of the present invention, when A is LiM2O2Or LiM3 2O4In this case, the calcination was performed in air.
In a preferred embodiment of the present invention, a carbon material is added during the preparation of the a precursor to coat the surface of the a precursor with the first carbon layer.
In a preferred embodiment of the present invention, the carbon material is conductive carbon or an organic carbon source, and the conductive carbon is at least one of artificial graphite, natural graphite, acetylene black, carbon black, mesocarbon microbeads, carbon nanotubes, carbon nanofibers, graphene, superconducting carbon black, and superconducting carbon fibers; the organic carbon source is at least one of phenolic resin, polyvinyl alcohol, asphalt and sucrose.
In a preferred embodiment of the present invention, a carbon material is added to the precursor a at the time of the pre-firing.
In a preferred embodiment of the present invention, the precursor a and the carbon material are mixed and then subjected to constant temperature pre-firing to obtain a precursor a having a first carbon layer coated on the surface thereof.
In the embodiment of the present invention, the amount of the carbon material is conventionally selected in the industry, and is not particularly limited herein.
In the embodiment of the invention, when the A precursor is LiM2O2And LiM3 2O4In this case, the particle size of the precursor A is conventionally selected.
In the embodiment of the invention, when the A precursor is LiM1PO4In this case, the particle size of the precursor A is conventionally selected.
In the embodiment of the present invention, LiC6The preparation method of the precursor comprises the following steps: an electrochemical cell is provided which uses C as a cathode, Li as an anode, and lithium hexafluorophosphate, tetraethylammonium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate (V), lithium trifluoromethanesulfonate, a dry solid polymer, a gel polymer or lithium bistrifluoromethylsulfonimide as an electrolyte, and a voltage of 0.5 to 2.5V is applied to the electrochemical cell in a protective gas to ionize the Li ionized from the anode+Deposited on the cathode C to obtain LiC6And (3) precursor.
In the embodiment of the invention, the deposited cathode is dried at 40-100 ℃ under the vacuum condition, and LiC is obtained6Precursor slave cathodeStripping off the silicon carbide, and performing ball milling or sanding to obtain nanoscale LiC6And (3) precursor.
In an embodiment of the present invention, LiC at the nanoscale6The surface of the precursor is coated with a second carbon layer.
In the embodiment of the invention, the LiC with the nanometer level is used6Mixing the precursor with a carbon material, and sintering at 40-300 ℃ for 5-10min in a protective gas to obtain LiC with the surface coated with a second carbon layer6And (3) precursor.
In the embodiment of the invention, the carbon material is conductive carbon or an organic carbon source, and the conductive carbon is at least one of artificial graphite, natural graphite, acetylene black, carbon black, mesocarbon microbeads, carbon nanotubes, carbon nanofibers, graphene, superconducting carbon black and superconducting carbon fibers; the organic carbon source is at least one of phenolic resin, polyvinyl alcohol, asphalt and sucrose.
In the embodiment of the present invention, LiC6The surface of the precursor is coated with a carbon layer, so that the LiC can be improved6Conductivity of the precursor.
In the embodiment of the present invention, LiC6The particle size of the precursor is 10-80 nm.
The invention adopts an electrochemical deposition method to prepare LiC6Precursors to ionize Li in a Li anode after applying a voltage to an electrochemical cell+，Li+Depositing the electrolyte on a cathode C to obtain LiC6The preparation method of the precursor is simple and effective, and the obtained LiC6The particle size of the precursor is nano-scale.
When the particle size of the A precursor is nano-scale, LiC6When the precursor material is nano-scale, in the sintering process, the A precursor and the LiC6The precursor is gathered to form a eutectic body, so that the lithium ion battery anode active material is obtained, and the capacity and the compaction density of the lithium ion battery anode active material are both high.
When the particle size of the A precursor is micron-sized, LiC6When the precursor material is in a nanometer level, a eutectic body is formed through sintering, the particle size is increased, and the micron-level lithium ion battery anode active material is obtained, and the capacity of the lithium ion battery anode active materialBoth the amount and the compacted density are higher.
In the embodiment of the invention, the specific operation of sintering the precursor of the lithium ion battery anode active material is as follows: heating the precursor of the positive active material of the lithium ion battery to 400-600 ℃ at the heating rate of 1-5 ℃/min, sintering at constant temperature for 5-10min, and cooling to normal temperature at the cooling rate of 1-5 ℃/min.
The invention has lower sintering temperature, and can avoid LiC in the sintering process6And (4) volatilizing. In addition, when the temperature rises to 400-600 ℃ at the temperature rise rate of 1-5 ℃/min, the formation of the precursor crystal lattice of the anode active material of the lithium ion battery is facilitated, the temperature is reduced to normal temperature at the temperature rise rate of 1-5 ℃/min, the temperature reduction rate is slow, and the formation of crystals with good crystal forms is facilitated.
In the embodiment of the invention, the whole sintering process is carried out in a constant temperature furnace, and any heat treatment equipment capable of uniformly heating under the protection of atmosphere can be used in the sintering process, such as a vacuum furnace, a box furnace, a tunnel furnace, a rotary atmosphere furnace, a bell jar furnace, a tubular furnace, a shuttle furnace or a pushed slab kiln.
In an embodiment of the present invention, the protective gas is at least one of nitrogen, argon and helium.
In the embodiment of the present invention, the pre-fired A precursor and LiC are mixed6The method for uniformly mixing the precursors can be stirring, ultrasonic, ball milling, sand milling or high-speed dispersion, and only the presintered A precursor and the LiC are required to be mixed6The precursor is mixed uniformly, and the specific mode is not particularly limited.
In the embodiment of the present invention, the pre-fired A precursor and LiC are mixed6And after the precursors are uniformly mixed, adding a carbon material to obtain a precursor of the lithium ion battery anode active material, and then sintering the precursor for 5min-2h at the constant temperature of 300-700 ℃ in a protective gas to obtain the lithium ion battery anode active material with the surface coated with a third carbon layer. Here, the surface A and LiC in the obtained positive electrode active material of the lithium ion battery are referred to6The surface is coated with a third carbon layer which contains A and LiC6。
In the embodiment of the present invention, LiC is used6Precursor and after pre-sinteringThe precursor A coated with the first carbon layer on the surface is uniformly mixed, then a carbon material is added to obtain a precursor of the lithium ion battery anode active material, and then the precursor is sintered for 5min-2h at the constant temperature of 300-700 ℃ in a protective gas, so that the surface of the obtained lithium ion battery anode active material is coated with a third carbon layer. The third carbon layer simultaneously contains LiC6And a coated with a first carbon layer.
In the embodiment of the present invention, the pre-fired a precursor and the LiC coated with the second carbon layer on the surface are mixed6And after the precursors are uniformly mixed, adding a carbon material to obtain a precursor of the lithium ion battery anode active material, and then sintering the precursor for 5min-2h at the constant temperature of 300-700 ℃ in a protective gas to obtain the lithium ion battery anode active material with the surface coated with a third carbon layer. The third carbon layer contains A and LiC coated with the second carbon layer6。
In the embodiment of the present invention, the a precursor coated with the first carbon layer on the surface and the LiC coated with the second carbon layer on the surface after the pre-firing are mixed6And after the precursors are uniformly mixed, adding a carbon material to obtain a precursor of the lithium ion battery anode active material, and then sintering the precursor for 5min-2h at the constant temperature of 300-700 ℃ in a protective gas to obtain the lithium ion battery anode active material with the surface coated with a third carbon layer. The third carbon layer contains both A coated with the first carbon layer and LiC coated with the second carbon layer6。
In the embodiment of the invention, x is more than or equal to 0.01 and less than or equal to 0.6.
In the embodiment of the invention, x is more than or equal to 0.05 and less than or equal to 0.4, and when x is more than or equal to 0.05 and less than or equal to 0.4, A and LiC6The positive active material has a proper proportion, and can have good stability and better electrochemical performance.
In the embodiment of the invention, x is more than or equal to 0.1 and less than or equal to 0.2.
In the embodiment of the invention, when A is LiM1PO4The particle diameter of the lithium ion battery anode active material is nano-scale or micron-scale, and the compaction density is 2.3-2.5g/cm3。
In the embodiment of the invention, when A is LiM2O2Or LiM3 2O4The particle diameter of the lithium ion battery anode active material is micron-sized, and the compaction density is 3.9-4.2g/cm3。
In the method for preparing the lithium ion battery cathode active material provided by the second aspect of the embodiment of the invention, the pre-sintered A precursor and the LiC are used6The precursor is mixed and sintered at a certain temperature and time, the sintering time is short, the method is simple, easy, unique and effective, the prepared lithium ion battery anode active material has high capacity, and in addition, the lithium ion battery anode active material has good stability and good conductivity.
In a third aspect, the present invention provides a lithium ion battery comprising the positive electrode active material of the lithium ion battery provided in the first aspect of the embodiments of the present invention.
The lithium ion battery comprises a positive pole piece, a negative pole piece, a diaphragm, electrolyte and a shell, wherein the positive pole piece consists of a current collector, the lithium ion battery positive active material provided by the first aspect of the invention, a conductive agent and a binder.
In the embodiment of the invention, the current collector is an aluminum foil, a nickel mesh or an aluminum-plastic composite film.
In an embodiment of the present invention, the conductive agent is acetylene black.
In the embodiment of the invention, the binder is polyvinylidene fluoride (PVDF), styrene butadiene rubber latex (SBR) or sodium carboxymethylcellulose (CMC).
The selection of the negative electrode plate, the separator, the electrolyte and the housing is the prior art in the industry, and is not limited herein.
The lithium ion battery provided by the third aspect of the embodiment of the invention has the advantages of excellent discharge capacity, higher energy density and better cycle performance.
Example 1:
a preparation method of a positive active material of a lithium ion battery comprises the following steps:
(1) preparation of LiFePO4Precursor body
1mol of LiH2PO4Dissolved in water to form LiH2PO4Solution, 1mol of simple substance iron is placed in glacial acetic acid, andLiH2PO4mixing the solution to obtain a mixed solution, heating the mixed solution to 40 ℃, reacting for 100min, and after the reaction is finished, carrying out spray drying to obtain the nanoscale LiFePO4A precursor; LiFePO is put in argon gas4Mixing the precursor and artificial graphite, pre-sintering at a constant temperature of 200 ℃ for 5h, and naturally cooling to room temperature to obtain a pre-sintered precursor A; the surface of the presintered precursor A is coated with a first carbon layer;
(2) preparation of LiC6Precursor body
An electrochemical cell is provided in which a cathode is C, an anode is Li, and lithium hexafluorophosphate is an electrolyte, wherein Li ionized from the anode is applied to the electrochemical cell at a voltage of 0.5 to 2.5V in an argon gas+Depositing on cathode C, drying the deposited cathode at 40 deg.C under vacuum condition, and collecting LiC6Stripping the precursor from the cathode, and then performing ball milling to obtain nanoscale LiC6Precursor, nano-scale LiC6Mixing the precursor with artificial graphite, and sintering at 100 deg.C for 6min in protective gas to obtain LiC coated with second carbon layer6And (3) precursor.
(3) Preparation (LiFePO)4)1-x·(LiC6)x
Pre-burning the A precursor and LiC coated with a second carbon layer on the surface6Uniformly mixing the precursors according to a molar ratio of 0.9:0.1 to obtain a precursor of the lithium ion battery anode active material, heating the precursor of the lithium ion battery anode active material to 400 ℃ at a heating rate of 1 ℃/min in argon gas, sintering at a constant temperature for 10min, and cooling to normal temperature at a cooling rate of 1 ℃/min to obtain the lithium ion battery anode active material (LiFePO)4)0.9·(LiC6)0.1。
Preparation method of lithium ion battery
800 grams of the lithium ion battery positive active material (LiFePO) prepared according to the above method4)0.9·(LiC6)0.1100 g of acetylene black as a conductive agent, 100 g of polyvinylidene fluoride (PVDF) as a binder, and 800 g of N-methylpyrrolidone solution (NMP solution)Liquid), stirring for 2 hours in a vacuum stirrer to prepare anode slurry;
the anode slurry is uniformly coated on an aluminum foil, dried at 110 ℃, rolled and cut into anode plates with the size of 93 x 122 mm.
Adding 920 g of negative active material natural graphite, 30 g of binder styrene butadiene rubber latex (SBR) and 30 g of sodium carboxymethylcellulose (CMC) into 500 g of water, stirring for 2h in a vacuum stirrer to prepare negative slurry, uniformly coating the negative slurry on a copper foil, drying at 120 ℃, and rolling to obtain the lithium ion battery negative pole piece.
Using a commercially available electrolyte comprising ethylene carbonate and LiPF6And an organic solvent.
The lithium ion battery positive electrode piece, the lithium ion battery negative electrode piece and the diaphragm prepared in the embodiment 1 are sequentially stacked and wound into a coiled battery cell by a winding machine, the obtained battery cell is placed into a shell with an opening at one end, the electrolyte prepared in the embodiment 1 is injected, and the lithium ion battery is prepared after sealing.
The lithium ion battery prepared in example 1 is subjected to a cycle performance test, the charging and discharging voltage is 2.0-3.8V, the test result is shown in fig. 1, and fig. 1 is a cycle performance diagram of the lithium ion battery prepared in example 1 of the invention; as can be seen from FIG. 1, the (LiFePO) is used4)0.9·(Li2C)0.1The lithium ion battery made of the positive electrode active material has a 1.0C charge-discharge cycle performance curve chart, and as can be seen from the chart, the capacity retention rate is 99.9% after 1C cycle 100 times, and the cycle performance is good.
Fig. 2 is a cycle performance diagram of the lithium ion battery prepared in example 1 of the present invention at different magnifications (discharge magnifications are 1.0C, 1.5C, 2.0C, 2.5C, and 3.0C, respectively). The results are shown in FIG. 2. As can be seen from FIG. 2, when the discharge is carried out at a rate of 1.0C, the first gram capacity of the discharge is 168mAh/g, and the gram capacity of the discharge after 4 times of circulation is still 168 mAh/g. When the lithium battery is discharged under the rate of 1.5C, the first discharging gram capacity is 164mAh/g, and the discharging gram capacity is still 164mAh/g after 4 times of circulation. When the lithium battery is discharged under the 2.0C multiplying power, the first discharging gram capacity is 160mAh/g, and the discharging gram capacity is still 160mAh/g after the lithium battery is circulated for 4 times. When the discharge is carried out under the multiplying power of 2.5C,the first discharge gram capacity is 156mAh/g, and the discharge gram capacity is still 156mAh/g after 4 times of circulation. When the lithium ion battery is charged and discharged under the multiplying power of 3.0C, the first gram of capacity discharged is 154mAh/g, and the gram of capacity discharged after 4 times of circulation is still 154 mAh/g. The 3.0C capacity was 91.6% of the 1.0C capacity. After 22 cycles, the discharge gram capacity at 1.0 ℃ is close to 168mAh/g, which shows that the lithium ion battery cathode active material prepared in the embodiment 1 of the invention has good discharge performance, higher capacity and good cycle performance at different multiplying powers, thereby showing that the lithium ion battery cathode active material (LiFePO) prepared in the embodiment of the invention4)1-x·(LiC6)xCan be assembled into a battery with high capacity, high multiplying power and good cycle performance.
Example 2:
a preparation method of a positive active material of a lithium ion battery comprises the following steps:
(1) preparation of LiFePO4Precursor body
1mol of LiH2PO4Dissolved in water to form LiFePO4Solution, 1mol of simple substance iron is placed in glacial acetic acid and then is mixed with LiH2PO4Mixing the solution to obtain a mixed solution, heating the mixed solution to 40 ℃, reacting for 100min, and after the reaction is finished, carrying out spray drying to obtain the nanoscale LiFePO4A precursor; LiFePO is put in argon gas4Mixing the precursor and artificial graphite, pre-sintering at a constant temperature of 500 ℃ for 1h, and naturally cooling to room temperature to obtain a pre-sintered precursor A; the surface of the presintered precursor A is coated with a first carbon layer;
(2) preparation of LiC6Precursor body
An electrochemical cell is provided in which a cathode is C, an anode is Li, and lithium hexafluorophosphate is an electrolyte, and Li ionized in the anode is applied to the electrochemical cell by applying a voltage of 0.5 to 2.5V in an argon gas atmosphere+Depositing on cathode C, drying the deposited cathode at 100 deg.C under vacuum condition, and collecting LiC6Stripping the precursor from the cathode, and then performing ball milling to obtain nanoscale LiC6Precursor, nano-scale LiC6Mixing the precursor and artificial graphite, and then putting the mixture in argon gas at 300 DEG CSintering for 5min to obtain LiC coated with a second carbon layer6And (3) precursor.
(3) Preparation (LiFePO)4)1-x·(LiC6)x
Pre-burning the A precursor and LiC coated with a second carbon layer on the surface6Uniformly mixing the precursors according to a molar ratio of 0.95:0.05, adding artificial graphite, uniformly mixing to obtain a lithium ion battery anode active material precursor, heating the lithium ion battery anode active material precursor to 600 ℃ at a heating rate of 5 ℃/min in argon gas, sintering at a constant temperature for 5min, and cooling to normal temperature at a cooling rate of 5 ℃/min to obtain a lithium ion battery anode active material (LiFePO)4)0.95·(LiC6)0.05. The surface of the positive active material of the lithium ion battery is coated with a third carbon layer.
The preparation method of the lithium ion battery is the same as that of example 1.
Example 3:
a preparation method of a positive active material of a lithium ion battery comprises the following steps:
(1) preparation of LiFePO4Precursor body
1mol of LiH2PO4Dissolved in water to form LiH2PO4Solution, 1mol of simple substance iron is placed in glacial acetic acid and then is mixed with LiH2PO4Mixing the solution to obtain a mixed solution, heating the mixed solution to 40 ℃, reacting for 100min, and after the reaction is finished, carrying out spray drying to obtain the nanoscale LiFePO4A precursor; LiFePO is put in argon gas4Presintering the precursor at the constant temperature of 300 ℃ for 2h, and naturally cooling to room temperature to obtain a presintered precursor A;
(2) preparation of LiC6Precursor body
An electrochemical cell is provided in which a cathode is C, an anode is Li, and lithium hexafluorophosphate is an electrolyte, and Li ionized from the anode is applied to the electrochemical cell by applying a voltage of 0.5 to 2.5V in an argon gas atmosphere+Depositing on cathode C, drying the deposited cathode at 100 deg.C under vacuum condition, and collecting LiC6The precursor is stripped from the cathode, thenThen ball milling is carried out to obtain nano LiC6And (3) precursor.
(3) Preparation (LiFePO)4)1-x·(LiC6)x
Pre-burning the A precursor and LiC6Uniformly mixing the precursors according to a molar ratio of 0.6:0.4 to obtain a precursor of the lithium ion battery anode active material, heating the precursor of the lithium ion battery anode active material to 500 ℃ at a heating rate of 3 ℃/min in argon gas, sintering at a constant temperature for 8min, and cooling to normal temperature at a cooling rate of 3 ℃/min to obtain the lithium ion battery anode active material (LiFePO)4)0.6·(LiC6)0.4。
The preparation method of the lithium ion battery is the same as that of example 1.
Example 4:
a preparation method of a positive active material of a lithium ion battery comprises the following steps:
(1) preparation of LiCoO2Precursor body
Mixing lithium carbonate and cobalt carbonate according to a molar ratio of 1:1, heating the mixture in air at 900 ℃ for 5 hours, and forming micron-sized LiCoO by a solid-phase synthesis method2A precursor; in air, LiCoO2Mixing the precursor and artificial graphite, presintering at the constant temperature of 300 ℃ for 2h, and naturally cooling to room temperature to obtain a presintered precursor A; the surface of the presintered A precursor is coated with a first carbon layer;
(2) preparation of LiC6Precursor body
An electrochemical cell is provided in which a cathode is C, an anode is Li, and lithium hexafluorophosphate is an electrolyte, and Li ionized from the anode is applied to the electrochemical cell by applying a voltage of 0.5 to 2.5V in an argon gas atmosphere+Depositing on cathode C, drying the deposited cathode at 100 deg.C under vacuum condition, and collecting LiC6Stripping the precursor from the cathode, and then performing ball milling to obtain nanoscale LiC6Precursor, nano-scale LiC6Mixing the precursor with artificial graphite, and sintering at 200 deg.C for 6min in argon gas to obtain LiC coated with second carbon layer6And (3) precursor.
(3) Preparation (LiCoO)2)1-x·(LiC6)x
Pre-sintering the A precursor coated with the first carbon layer and the LiC coated with the second carbon layer6Uniformly mixing the precursors according to a molar ratio of 0.6:0.4, adding artificial graphite, uniformly mixing to obtain a lithium ion battery positive active material precursor, heating the lithium ion battery positive active material precursor to 500 ℃ at a heating rate of 3 ℃/min in argon gas, sintering at a constant temperature for 8min, and cooling to normal temperature at a cooling rate of 3 ℃/min to obtain the lithium ion battery positive active material (LiCoO)2)0.6·(LiC6)0.4. The surface of the positive active material of the lithium ion battery is coated with a third carbon layer.
The preparation method of the lithium ion battery is the same as that of example 1.
Example 5:
a preparation method of a positive active material of a lithium ion battery comprises the following steps:
(1) preparation of LiMn2O4Precursor body
According to LiMn2O4Weighing lithium carbonate and electrolytic manganese dioxide according to the stoichiometric ratio, grinding the lithium carbonate and the electrolytic manganese dioxide to uniformly mix the lithium carbonate and the electrolytic manganese dioxide, drying the mixture for 2 hours at 100 ℃, and sintering the mixture for 12 hours at 850 ℃ in air atmosphere to obtain micron-sized LiMn2O4A precursor; in the air, LiMn is added2O4Mixing the precursor and artificial graphite, presintering at the constant temperature of 300 ℃ for 2h, and naturally cooling to room temperature to obtain a presintered precursor A; the surface of the presintered A precursor is coated with a first carbon layer;
(2) preparation of LiC6Precursor body
An electrochemical cell is provided in which a cathode is C, an anode is Li, and lithium hexafluorophosphate is an electrolyte, and Li ionized from the anode is applied to the electrochemical cell by applying a voltage of 0.5 to 2.5V in an argon gas atmosphere+Depositing on cathode C, drying the deposited cathode at 100 deg.C under vacuum condition, and obtaining LiC6Stripping the precursor from the cathode, and then performing ball milling to obtain nanoscale LiC6Precursor, nano-scale LiC6Precursors andmixing artificial graphite, and sintering at 40 deg.C for 10min in argon gas to obtain LiC coated with second carbon layer6And (3) precursor.
(3) Preparation (LiMn)2O4)1-x·(LiC6)x
Pre-burning the A precursor and LiC coated with a second carbon layer on the surface6Uniformly mixing the precursors according to a molar ratio of 0.6:0.4, adding artificial graphite, uniformly mixing to obtain a lithium ion battery positive active material precursor, heating the lithium ion battery positive active material precursor to 500 ℃ at a heating rate of 3 ℃/min in argon gas, sintering at a constant temperature for 8min, and cooling to normal temperature at a cooling rate of 3 ℃/min to obtain the lithium ion battery positive active material (LiMn)2O4)0.6(LiC6)0.4. The surface of the positive active material of the lithium ion battery is coated with a third carbon layer.
The preparation method of the lithium ion battery is the same as that of example 1.
Comparative example 1
Using LiFePO alone4、LiCoO2、LiMn2O4The material was used as a positive electrode active material, and an electrode and a lithium ion battery were manufactured by the same manufacturing method as in example one.
Comparative example 2
Mixing LiFePO4And LiC6The obtained mixed material was used as a positive electrode active material, and an electrode and a lithium ion battery were produced by the same production method as in example one.
The battery of example 1 described above and comparative examples 1-2 were compared in performance, and the results are shown in the following table.
Table 1 comparison of capacity and energy density of lithium ion batteries of the invention and comparative example 1
Lithium ion battery (0)<x<1) Maximum capacity boost rate Maximum energy density increase rate
Positive electrode active material (LiFePO)4)1-x·(LiC6)x 25％ 25％
Positive electrode active material (LiCoO)2)1-x·(LiC6)x 20％ 20％
Positive electrode active material (LiMn)2O4)1-x·(LiC6)x 20％ 20％
Table 1 shows a comparison of the capacity and energy density of the lithium ion battery of the present invention and the lithium ion battery of comparative example 1, and from table 1 it can be seen that LiFePO alone is compared to comparative example 14The anode active material of the invention is (LiFePO)4)1-x·(LiC6)xThe capacity of the lithium ion battery is improved by 25% at most, and the energy density is improved by 25% at most. LiCoO alone versus comparative example 12The positive active material of the present invention is (LiCoO)2)1-x·(LiC6)xThe capacity of the lithium ion battery is improved by 20% at most, and the energy density is improved by 20% at most. LiMn alone relative to comparative example 12O4The positive active material of the invention is (LiMn)2O4)1-x·(LiC6)xLithium ion ofThe capacity of the battery is improved by 20% at most, and the energy density is improved by 20% at most. The above lithium ion batteries both had an average capacity increase rate and an average energy density increase rate of 10% or more, relative to comparative example 1. It is emphasized that here only (LiFePO)4)1-x·(LiC6)x、(LiCoO2)1-x·(LiC6)xAnd (LiMn)2O4)1-x·(LiC6)xFor example, the capacity and energy density of lithium ion batteries made of other lithium ion battery positive electrode active materials protected by the invention are greatly improved compared with the capacity and energy density of the conventional positive electrode active materials in the prior art.
Table 2 shows a comparison of the capacity, energy density and cycle performance of the lithium ion battery of the present invention obtained in example 1 and comparative examples 1-2
Figure GDF0000008894430000171
From Table 2, it can be seen that pure LiFePO as in comparative example 14Compared with the lithium ion battery prepared by using the anode active material, the anode active material of the lithium ion battery provided by the embodiment 1 of the invention can improve the energy density and the capacity of the lithium ion battery to a certain extent. Therefore, the lithium ion battery positive electrode active material provided in embodiment 1 of the present invention enables a lithium ion battery to have a higher energy density.
And LiFePO in comparative example 24And LiC6Compared with the lithium ion battery prepared by taking the physical mixed material as the cathode active material, the cathode active material of the lithium ion battery provided by the embodiment 1 of the invention can greatly increase the capacity, the energy density and the cycle performance of the lithium ion battery. In summary, according to the positive active material of the lithium ion battery provided by the embodiment of the invention, the LiC is added into the common positive active material6And the energy density of the lithium ion battery is improved, so that the lithium ion battery can be widely applied to the field of energy storage. Meanwhile, the lithium ion battery anode active material has good cycle performance and high stability.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (8)

1. A positive electrode active material for a lithium ion battery, comprising (A)1-x·(LiC6)xWherein, 0<x<1, A is LiM1PO4And LiM2O2At least one of (1), M1Or M2At least one selected from the group consisting of iron, cobalt, manganese, nickel, aluminum and vanadium, the surface of A being coated with a first carbon layer while LiC6Is coated with a second carbon layer.
2. The positive electrode active material for lithium ion batteries according to claim 1, wherein x is in a range of 0.05. ltoreq. x.ltoreq.0.4.
3. A preparation method of a positive electrode active material of a lithium ion battery is characterized by comprising the following steps:
providing a precursor A; a is LiM1PO4And LiM2O2At least one of (1), M1Or M2At least one of iron, cobalt, manganese, nickel, aluminum and vanadium is selected, the precursor A is presintered in protective gas or air at a constant temperature of 200-500 ℃ for 1-5h, then the temperature is naturally reduced to room temperature, and a carbon material is added during presintering of the precursor A to obtain the precursor A with the surface coated with the first carbon layer;
mixing nano-scale LiC6Mixing the precursor and a carbon material, and sintering to obtain LiC with the surface coated with a second carbon layer6A precursor;
coating the surface with a firstPrecursor A of the carbon layer and LiC coated with the second carbon layer6Uniformly mixing the precursors according to the molar ratio of 1-x: x to obtain a precursor of the lithium ion battery anode active material, and sintering the precursor of the lithium ion battery anode active material at the constant temperature of 300-700 ℃ for 5min-2h in a protective gas to obtain the lithium ion battery anode active material, wherein the lithium ion battery anode active material comprises (A)1-x·(LiC6)x，0<x<1, A is coated with the first carbon layer while LiC6Is coated with the second carbon layer.
4. The method for preparing the positive electrode active material of the lithium ion battery according to claim 3, wherein the sintering of the precursor of the positive electrode active material of the lithium ion battery is specifically performed by: heating the precursor of the lithium ion battery anode active material to 400-600 ℃ at the heating rate of 1-5 ℃/min, sintering at constant temperature for 5-10min, and cooling to normal temperature at the cooling rate of 1-5 ℃/min.
5. The method of preparing a positive active material for a lithium ion battery according to claim 3, wherein the LiC is6The preparation method of the precursor comprises the following steps: an electrochemical cell is provided which uses C as a cathode, Li as an anode, and lithium hexafluorophosphate, tetraethylammonium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, a dry solid polymer, a gel polymer or lithium bistrifluoromethylsulfonimide as an electrolyte, wherein a voltage of 0.5-2.5V is applied to the electrochemical cell in a protective gas to ionize Li ionized from the anode+Depositing on a cathode C to obtain the LiC6And (3) precursor.
6. The method for preparing the positive active material of the lithium ion battery according to claim 5, wherein the deposited cathode is dried at 40-100 ℃ under vacuum condition, and the LiC is prepared6Stripping the precursor from the cathode, and performing ball milling or sanding to obtain nanoscale LiC6And (3) precursor.
7. The method for preparing a positive active material for a lithium ion battery according to claim 3 or 6, wherein the LiC is6The particle size of the precursor is 10-80 nm.
8. A lithium ion battery comprising the positive electrode active material for a lithium ion battery according to any one of claims 1 to 2.
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CN101950801A (en) * 2010-09-21 2011-01-19 新疆金盛科达有色金属新材料有限责任公司 Preparation method of positive electrode material LiFePO4/C of lithium ion battery
CN103078105A (en) * 2013-01-23 2013-05-01 宁德新能源科技有限公司 Lithium ion battery, positive active material thereof and preparation method of positive active material
CN103107309A (en) * 2013-01-31 2013-05-15 中国科学技术大学 Lithium ion battery positive pole and preparation method thereof

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