CN113871592B

CN113871592B - Coated composite material and preparation method and application thereof

Info

Publication number: CN113871592B
Application number: CN202111120367.3A
Authority: CN
Inventors: 谭强强; 夏青
Original assignee: Institute of Process Engineering of CAS
Current assignee: Institute of Process Engineering of CAS
Priority date: 2021-09-24
Filing date: 2021-09-24
Publication date: 2023-04-11
Anticipated expiration: 2041-09-24
Also published as: CN113871592A

Abstract

The invention provides a coated composite material and a preparation method and application thereof, the coated composite material comprises an electrode material core and a coating layer coated on the surface of the electrode material core, the coating layer comprises an Fe-F-O compound, a heteroatom doped carbon material, a carbon nanotube compound and an amorphous carbon material, and the preparation method comprises the following steps: (1) Mixing an electrode material inner core, an Fe-F-O compound, a heteroatom doped carbon material, a carbon nano tube and an organic solvent to obtain a mixed solution; (2) And (2) drying the mixed solution obtained in the step (1) and then carrying out heat treatment to obtain the coated composite material. The prepared coated composite material can improve the cycle stability, reversible specific capacity, rate capability and first coulombic efficiency of the battery, and has wide application prospect.

Description

Coated composite material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of lithium ion battery materials, and particularly relates to a coated composite material and a preparation method and application thereof.

Background

With the rapid development of new energy automobiles, the lithium ion battery industry has entered a rapid development stage. The key materials influencing the performance of the lithium ion battery mainly comprise electrode materials, electrolyte, a diaphragm and the like. Among them, the electrode material is currently a major factor limiting the performance of the battery.

The lithium ion battery realizes large-scale application and simultaneously meets a series of requirements of low cost, safety, no natural resource limitation, high energy density and the like. The electrode materials of the lithium ion battery researched at present mainly comprise lithium cobaltate, lithium nickelate, lithium manganate with a spinel structure, lithium nickelate, lithium iron phosphate, silicon-based materials and the like. However, liCoO ₂ High cost, co ³⁺ Toxic, and the material is structurally unstable when overcharged; liNiO ₂ The synthesis conditions are harsh, part of lithium sites are occupied by nickel sites, the degree of order is low, and the reversibility is poor; the silicon-based material can expand in volume during charging and discharging processes, and the stability of the material is influenced. Therefore, in order to improve the comprehensive electrochemical performance of lithium ion batteries, various methods are used to improve the electrode materials to improve the conductivity, the cycling stability, the service life, the rate capability and the like of the lithium ion batteries.

CN109305700A discloses a preparation method of a positive electrode material containing a niobium/tantalum cation disordered rock salt structure, which adopts a stable water-soluble Nb/Ta precursor to synthesize the positive electrode material containing the Nb/Ta cation disordered rock salt structure oxide by a wet chemical method. The initial discharge capacity of the obtained material is up to 250mAh/g, the rate capability and the cycle performance are excellent, and the capacity retention rate after 0.5C cycle for 100 times is more than 85%.

CN112680791A discloses a single crystal type IV-VI-VIII family lithium-rich disordered rock salt structureThe positive electrode material has the following general formula: li _1+a Ti _b W _c Ni _d O ₂ Wherein, 0.1<a<0.3，0.1<b<0.4，0.1<c<0.4，0.1<d<0.4, and a +4b +6c +2d =3. The capacity of the obtained material is larger than 257mAh/g at 0.05C multiplying power (1C = 200mA/g) for the first time, and then the capacity retention rate is larger than 48% after the charge and discharge test is carried out at 0.1C multiplying power after the cycle for 50 weeks.

CN105406067A discloses a preparation method of a titanium oxide modified lithium manganese iron phosphate anode material, which adopts titanium dioxide to modify the surface of the lithium manganese iron phosphate anode material so as to improve the cycle service life and stability of the lithium manganese iron phosphate anode material.

However, the reversible specific capacity, rate capability and cycle performance of the electrode material obtained by the scheme are all to be improved, so that the development of a lithium ion battery electrode material with more excellent performance has important significance in the field.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a coated composite material and a preparation method and application thereof. The electrode material synthesized by the invention can improve the cycle stability, reversible specific capacity, rate capability and first coulomb efficiency of the battery when being applied to the lithium ion battery, and has wide application prospect.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a coated composite material, including an electrode material core and a coating layer coated on a surface of the electrode material core, wherein the coating layer includes an Fe-F-O compound, a heteroatom-doped carbon material, a carbon nanotube composite, and an amorphous carbon material.

The invention uses Fe-F-O compound, heteroatom doped carbon material, carbon nano tube and amorphous carbon material as cladding to construct cladding, the four materials have synergistic effect and are cladded on the surface of an electrode, the cycle stability, reversible specific capacity, rate capability and first coulomb efficiency of the cladded composite material can be improved, and the technical principle is as follows: the first, fe-F-O compound has the ability of releasing and inserting lithium, and is used for the coating layer, which not only provides a physical barrier layer between the electrode and the electrolyte, inhibits the side reaction, but also improves the charge transfer kinetics, is beneficial to the transmission of lithium ions between the electrode material core and the electrolyte, and enables the coating type composite material to have better electrochemical performance. Secondly, the heteroatom doped carbon material and the carbon nano tube have good conductivity, so that the electronic conductance of the inner core of the electrode material can be improved, and the overall conductivity of the material is improved; meanwhile, the heteroatom doped carbon material and the carbon nano tube have the advantages of high mechanical property, good thermal stability and the like, can keep stable structure after charge/discharge cycle, and improve the cycle stability of the material. Thirdly, the amorphous carbon can bond the material particles and improve the stability of the whole material.

Preferably, the electrode material core is a positive electrode material core or a negative electrode material core, and the coating layer can achieve a good coating effect on both the positive electrode material core and the negative electrode material core, and is preferably the positive electrode material core.

Preferably, the core of the cathode material is of a disordered cubic rock salt structure, wherein anions (O) are contained in the core ^2- And F ^- ) Occupying the sites of the face centered cubic lattice, and cations (lithium ions and transition metal ions) randomly occupy the face centered cubic sublattices of the octahedral voids.

Preferably, the chemical formula of the cathode material core with the disordered cubic rock salt structure is Li _1+x M _1-x O _2-y F _y Wherein x is 0.1. Ltoreq. X.ltoreq.0.3, for example, 0.1, 0.15, 0.2, 0.25, or 0.3, etc., y is 0 < y.ltoreq.0.3, for example, 0.05, 0.1, 0.15, 0.2, 0.25, or 0.3, etc., and M is a transition metal element.

Preferably, the transition metal element is any one or a combination of at least two of Mn, ni, V, mo, fe, ti, zr, cr, co, cu, zn, nb, sc, or Y, and may be, for example, mn, ni, V, a combination of Fe and Ti, a combination of Zr and Cr, or a combination of Fe, co and Ti, and the like, and is preferably any one or a combination of at least two of Mn, ni, V, mo, fe, or Ti.

Preferably, the Fe-F-O composition is FeF _x At least one ofWith Fe _y O _z Wherein 2. Ltoreq. X.ltoreq.3, for example 2 or 3,0<y.ltoreq.3, for example 0.5, 1, 2 or 3, 1. Ltoreq.z.ltoreq.4, for example 1, 2, 3 or 4.

In an alternative embodiment, the Fe-F-O composition may specifically be FeF ₂ And/or FeF ₃ With FeO, fe ₂ O ₃ Or Fe ₃ O ₄ At least one of (a) and (b). For example, feF may be used ₂ And Fe ₂ O ₃ Composition formed, feF ₂ Composition formed with FeO, feF ₂ And Fe ₃ O ₄ Composition formed, feF ₂ 、FeF ₃ And Fe ₃ O ₄ Composition formed, feF ₃ 、Fe ₂ O ₃ And Fe ₃ O ₄ The resulting composition, or FeF ₂ 、FeF ₃ And Fe ₂ O ₃ The resulting composition, and the like.

Preferably, the Fe-F-O compound is FeF _x And Fe _y O _z The resulting composition, wherein 2. Ltoreq. X.ltoreq.3, 2. Ltoreq. Y.ltoreq.3, 3. Ltoreq. Z.ltoreq.4, may be in particular FeF ₂ And Fe ₂ O ₃ Of FeF ₂ And Fe ₃ O ₄ Of FeF ₃ And Fe ₂ O ₃ Of FeF ₃ And Fe ₃ O ₄ The composition of (1).

Preferably, the Fe-F-O composition is FeF ₂ 、FeF ₃ 、Fe ₂ O ₃ And Fe ₃ O ₄ The resulting composition.

Preferably, the heteroatom-doped carbon material is a boron, nitrogen, sulfur and phosphorus co-doped carbon material.

Preferably, the atomic ratio of boron, nitrogen, sulfur and phosphorus in the boron, nitrogen, sulfur and phosphorus co-doped carbon material is (0.5-1): (1-2): (0.5-1), wherein the selection range of boron (0.5-1) can be, for example, 0.5, 0.6, 0.8 or 1, the selection range of nitrogen (1-2) can be, for example, 1, 1.2, 1.5, 1.8 or 2, etc., the selection range of sulfur (1-2) can be, for example, 1, 1.2, 1.5, 1.8 or 2, etc., and the selection range of phosphorus (0.5-1) can be, for example, 0.5, 0.6, 0.8 or 1, etc.

The heteroatoms of the heteroatom doped carbon material have a synergistic effect, can provide short-range ultrafast electronic conductance, and can buffer the volume change of the inner core of the electrode material in the circulating process. By optimizing the atomic ratio of four atoms of boron, nitrogen, sulfur and phosphorus in the heteroatom doped carbon material, the microstructure of the heteroatom doped carbon material can be improved, and the electronic conductance of the heteroatom doped carbon material can be improved.

Preferably, the carbon nanotubes are single-walled carbon nanotubes and/or multi-walled carbon nanotubes, preferably multi-walled carbon nanotubes.

Preferably, the carbon nanotubes have an aspect ratio of 500 to 3000, such as 500, 750, 1000, 1500, 2000, 2500, 3000, etc., preferably 1000 to 2000, and when the aspect ratio is too short, the carbon nanotubes cannot form a long-range conductive path, and cannot construct a stable material structure, and when the aspect ratio is too long, the carbon nanotubes are wound around each other, and it is difficult to form a uniform coating structure on the core of the electrode material.

In a preferred embodiment of the coated composite material of the present invention, the particle size of the electrode material core is 100 to 2000nm, for example, 100nm, 200nm, 300nm, 500nm, 1000nm, 1500nm, 2000nm, and the like, preferably 300 to 1000nm.

The particle size of the electrode material core can influence the electrochemical performance of the coated composite material, when the particle size of the electrode material core is smaller, agglomeration is easily caused, the structure and the stability of the material are damaged, and when the particle size difference between the electrode material core and the outer layer particles is too small, a uniform coating layer is difficult to form on the surface of the coated material; when the particle size of the electrode material core is large, the electrochemical activity of the clad composite material is reduced.

Preferably, the particle size of the Fe-F-O compound is 20-100nm, such as 20nm, 30nm, 50nm, 80nm, or 100nm.

Preferably, the content of the electrode material core is 82 to 98.4%, for example, 82%, 85%, 87%, 90%, 92%, 95%, 97%, 98.4%, or the like, preferably 90 to 97%, based on 100% by mass of the coated composite material.

Preferably, the content of the Fe — F — O compound is 0.5 to 5%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or 5%, and preferably 1 to 3%, based on 100% by mass of the clad composite material.

Preferably, the content of the heteroatom-doped carbon material is 0.5 to 4%, for example, 0.5%, 1%, 2%, 2.5%, 3%, 3.5%, or 4%, preferably 1 to 3%, based on 100% by mass of the coated composite material.

Preferably, the content of the carbon nanotubes is 0.5 to 5%, for example, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or the like, preferably 0.5 to 2%, based on 100% by mass of the coated composite material.

Preferably, the content of the amorphous carbon material is 0.1 to 4%, for example, 0.1%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or the like, preferably 0.5 to 2%, based on 100% by mass of the coated composite material.

Preferably, the FeF is calculated by taking the mass of the Fe-F-O composition as 100 percent _x The content of (A) is 70 to 90%, and may be, for example, 70%, 75%, 80%, 85%, 90%, or the like.

The electrochemical performance of the coated composite material can be influenced by the contents of the Fe-F-O compound, the heteroatom doped carbon material and the carbon nano tube, and when the contents of the Fe-F-O compound, the heteroatom doped carbon material and the carbon nano tube in the coating layer are too high, the transmission of lithium ions between interfaces can be hindered, and the integral specific capacity of the material can be reduced; when the coating content is too low, the effects of stabilizing the material structure, improving the rate capability and the first coulombic efficiency cannot be achieved.

Preferably, the coating layer is coated on part of or all of the surface of the electrode material core, and can play a role in improving the cycling stability, reversible specific capacity, rate capability and initial coulomb efficiency of the material.

In a second aspect, the present invention provides a method of making a clad composite material as defined in the first aspect, the method comprising the steps of:

(1) Mixing an electrode material inner core, an Fe-F-O compound, a heteroatom doped carbon material, a carbon nano tube and an organic solution to obtain a mixed solution;

(2) And (2) drying the mixed solution obtained in the step (1) and then carrying out heat treatment to obtain the coated composite material.

According to the invention, the organic solvent is used as the carbon source and the solvent, so that the dispersibility of the electrode material core, the Fe-F-O compound, the heteroatom doped carbon material and the carbon nano tube is ensured, the organic solvent is converted into amorphous carbon after drying and heat treatment, and the prepared coated composite material has the advantages that the Fe-F-O compound, the heteroatom doped carbon material, the carbon nano tube and the amorphous carbon have good associativity and can form a stable coating layer, meanwhile, the coating layer formed by the four is uniformly coated on the surface of the electrode material core, so that the dispersibility is good, the structural stability of the electrode material core in the charge-discharge process can be enhanced, the volume change of the material is relieved, and the first coulomb efficiency, reversible capacity, rate capability and cycle stability of the coated composite material are improved.

Preferably, the heteroatom doped carbon material in the step (1) is prepared by the following steps: mixing boric acid, a nitrogen source, a sulfur source, a phosphorus source and a carbon source, transferring the mixture into a closed container, filling protective gas into the closed container, carrying out heat treatment on the closed container in the protective gas, and cooling to obtain the heteroatom doped carbon material.

Preferably, the nitrogen source is melamine and/or nitrilotriacetic acid, which may be, for example, melamine, nitrilotriacetic acid or a combination of melamine and nitrilotriacetic acid.

Preferably, the sulfur source is any one or a combination of at least two of sodium sulfide, sodium thiosulfate, thiourea, thiol, thiophenol, thioether, disulfide, polysulfide or cyclic sulfide, and may be, for example, sodium sulfide, sodium thiosulfate, thiourea, thiol, thiophenol, thioether, disulfide, polysulfide, cyclic sulfide, a combination of sodium sulfide and sodium thiosulfate, a combination of thiourea and thiol, a combination of disulfide and polysulfide, a combination of sodium thiosulfate, thiourea and thiol, a combination of thiophenol, thioether and disulfide, a combination of sodium thiosulfate, thiourea, thiol and thiophenol, or a combination of thiol, thiophenol, thioether, disulfide and polysulfide.

Preferably, the phosphorus source is any one or a combination of at least two of phosphonitrile trichloride chloride, adenosine triphosphate, adenosine diphosphate, phosphoenone pyruvate, phosphate ester, tetrakis hydroxymethyl phosphonium chloride, dimethyl vinylphosphate, hexachlorocyclotriphosphazene, polydichlorophosphazene, polyalkoxyphosphazene, polyaryloxy phosphazene or polyfluorooxyphosphazene, and may be, for example, phosphonitrile trichloride chloride, adenosine triphosphate, adenosine diphosphate, a combination of adenosine diphosphate and phosphoenone pyruvate, tetrakis hydroxymethyl phosphonium chloride, dimethyl vinylphosphate and hexachlorocyclotriphosphazene, dimethyl vinylphosphate, hexachlorocyclotriphosphazene, polydichlorophosphazene and polyalkoxyphosphazene, or a combination of adenosine diphosphate, phosphoenone pyruvate, phosphate ester, tetrakis hydroxymethyl phosphonium chloride and dimethyl vinylphosphate.

Preferably, the carbon source is any one of polyvinylpyrrolidone, poly (4-vinylpyridine) or polyethylene terephthalate or a combination of at least two thereof, and may be, for example, polyvinylpyrrolidone, poly (4-vinylpyridine), polyethylene terephthalate, a combination of polyvinylpyrrolidone and poly (4-vinylpyridine) or a combination of polyvinylpyrrolidone, poly (4-vinylpyridine) and polyethylene terephthalate.

Preferably, in the method for preparing the heteroatom-doped carbon material, the protective atmosphere is any one or a combination of at least two of nitrogen, argon or helium, and may be, for example, nitrogen, argon, a combination of argon and helium or a combination of nitrogen, argon and helium.

Preferably, in the method for preparing the heteroatom-doped carbon material, the temperature of the heat treatment is 350 to 500 ℃, and may be 350 ℃, 400 ℃, 450 ℃, 500 ℃ or the like, for example.

Preferably, in the preparation method of the heteroatom doped carbon material, the heat treatment is carried out for 1-4h, such as 1h, 1.5h, 2h, 2.5h, 3h, 3.5h or 4h.

Preferably, in the method for preparing the heteroatom-doped carbon material, the heating rate of the heat treatment is 2-10 ℃/min, for example, 2 ℃/min, 4 ℃/min, 6 ℃/min, 8 ℃/min, 10 ℃/min or the like.

As a preferred embodiment of the preparation method of the present invention, the mixing in step (1) is performed in the following manner: dispersing the electrode material inner core, the Fe-F-O compound, the heteroatom doped carbon material and the carbon nano tube in an organic solution, and uniformly dispersing by ultrasonic.

Preferably, the organic solution is any one of or a combination of at least two of ethylene glycol, glycerol or phenolic resin, and may be, for example, ethylene glycol, glycerol, phenolic resin, a combination of ethylene glycol and glycerol, a combination of glycerol and phenolic resin or a combination of ethylene glycol, glycerol and phenolic resin.

The preferable organic solvents of ethylene glycol, glycerol and phenolic resin in the invention have certain viscosity, can realize uniform dispersion of particles, can be carbonized in the heat treatment process to generate amorphous carbon, realize uniform coating and play a role in bonding the particles.

Preferably, the power of the ultrasound is 150-250W, such as 150W, 180W, 200W, 220W or 250W, etc., and the time of ultrasound is 20-60min, such as 20min, 30min, 40min, 50min or 60min, etc.

Preferably, the drying in the step (2) is spray drying, and granulation can be performed while drying, so that uniform coating of the coating layer is realized, particle agglomeration is reduced, and the effect is better than that of a common drying mode.

Preferably, the outlet temperature of the spray drying is 100-250 ℃, for example, 100 ℃, 110 ℃, 120 ℃, 150 ℃, 180 ℃, 200 ℃, 230 ℃ or 250 ℃ and the like.

The outlet temperature of the spray drying in the invention can influence the electrochemical performance of the material, when the temperature is too low, the coated composite material cannot be dried fully, and the uniform granulation effect cannot be realized, and when the temperature is too high, the uniform granulation degree can be influenced, and the electrochemical performance of the material is further influenced.

Preferably, the heat treatment of step (2) is performed under a protective atmosphere.

Preferably, the gas in the protective atmosphere in step (2) is any one of nitrogen, argon or helium or a combination of at least two of nitrogen, argon, helium, a combination of nitrogen and argon, a combination of argon and helium or a combination of nitrogen, argon and helium, and the like.

Preferably, the temperature of the heat treatment in step (2) is 300-600 ℃, such as 300 ℃, 350 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃ or 600 ℃.

Preferably, the heating rate of the heat treatment in step (2) is 1-10 deg.C/min, such as 1 deg.C/min, 2 deg.C/min, 4 deg.C/min, 6 deg.C/min, 8 deg.C/min, or 10 deg.C/min.

Preferably, the heat treatment in step (2) has a holding time of 0.5 to 6 hours, such as 0.5 hour, 0.8 hour, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours, preferably 1 to 4 hours.

In the invention, the heat treatment temperature in the step (2) can influence the electrochemical performance of the material, and when the heat treatment temperature is too low, the solvent cannot be completely carbonized, and the effects of bonding particles and conducting electricity cannot be achieved; when the heat treatment temperature is too high, the crystal grains grow along with the heat treatment temperature, and the lithium ion diffusion path is enlarged.

As a further preferable technical scheme of the preparation method of the invention, the preparation method comprises the following steps:

(1) Uniformly mixing boric acid, a nitrogen source, a sulfur source, a phosphorus source and a carbon source, and transferring the mixture into a closed container to make up for the fact that the container is filled with protective gas; carrying out heat treatment on the closed container at 350-500 ℃ for 1-4h, wherein the heating rate of the heat treatment is 2-10 ℃/min, and cooling to obtain the heteroatom doped carbon material;

(2) Dispersing an electrode material inner core, a Fe-F-O compound, a heteroatom doped carbon material and a carbon nano tube in an organic solution, and uniformly dispersing by ultrasonic to obtain a mixed solution;

(3) And (3) spray-drying the mixed solution obtained in the step (2) at the temperature of 100-250 ℃, then carrying out heat treatment in a protective atmosphere, heating to 300-600 ℃ at the heating rate of 1-10 ℃/min for heat treatment for 0.5-6h, and cooling to obtain the coated composite material.

In a third aspect, the present invention provides a lithium ion battery comprising the coated composite material according to the first aspect.

Compared with the prior art, the invention has the following beneficial effects:

(1) According to the invention, the Fe-F-O compound, the heteroatom doped carbon material, the carbon nano tube and the amorphous carbon material are used for constructing the coating layer, a physical barrier layer is provided between the electrode and the electrolyte, side reaction is inhibited, charge transfer kinetics is improved, the composite anode material has better electrochemical performance, and meanwhile, the four components have synergistic effect, so that the cycle stability, reversible specific capacity, rate capability and initial coulomb efficiency of the coated composite material are improved.

(2) The invention adopts a spray drying method to directly granulate the obtained coated composite material, so that the obtained coated composite material has uniform coating and uniform grain diameter.

(3) The preparation method of the coated composite material provided by the invention has the advantages of simple process, low requirement on equipment and relatively low cost, and is suitable for industrial production.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

The embodiment provides a coated composite material, which comprises an electrode material core and a coating layer coated on the surface of the electrode material core, wherein the coating layer comprises a Fe-F-O compound, a heteroatom-doped carbon material, a carbon nanotube composite and an amorphous carbon material, and the electrode material core is Li _1.2 Mo _0.7 Ti _0.1 O _1.8 F _0.2 The particle size is 1000nm, and the Fe-F-O compound is FeF with the mass ratio of 7 ₃ And Fe ₂ O ₃ The composition of (1), having an average particle diameter of 50nm,the heteroatom doped carbon material is a boron, nitrogen, sulfur and phosphorus co-doped composite carbon material, the atomic ratio of boron, nitrogen, sulfur and phosphorus is 0.8.

The mass of the coated composite material is 100%, the content of an electrode material core in the coated composite material is 93%, the mass of the Fe-F-O compound is 2%, the mass of the heteroatom doped carbon material is 3%, the mass of the carbon nano tube is 1%, and the mass of the amorphous carbon material is 1%. The preparation method of the coated composite material comprises the following steps:

(1) Mixing boric acid, melamine, sodium sulfide, tetrakis (hydroxymethyl) phosphonium chloride, polyvinylpyrrolidone and poly (4-vinylpyridine), transferring the mixture into a closed container, filling argon into the closed container, carrying out heat treatment on the closed container at 450 ℃ for 2.5h, wherein the heating rate of the heat treatment is 6 ℃/min, and cooling to obtain a heteroatom doped carbon material;

(2) Mixing Li _1.2 Mo _0.7 Ti _0.1 O _1.8 F _0.2 The Fe-F-O compound, the heteroatom doped carbon material and the multi-walled carbon nanotube are dispersed in glycerol and uniformly dispersed by ultrasonic; wherein the Fe-F-O compound is FeF with the mass ratio of 7 ₃ (trade name 011487) and Fe ₂ O ₃ (composition No. F299311);

(3) And (3) spray-drying the solution at the temperature of 120 ℃, then carrying out heat treatment in a nitrogen atmosphere, heating to 450 ℃ at the heating rate of 5 ℃/min for heat treatment for 2h, and cooling to obtain the coated composite material.

Example 2

The embodiment provides a coated composite material, which comprises an electrode material core and a coating layer coated on the surface of the electrode material core, wherein the coating layer comprises a Fe-F-O compound, a heteroatom-doped carbon material, a carbon nanotube composite and an amorphous carbon material, and the electrode material core is Li _1.1 Fe _0.6 V _0.3 O _1.8 F _0.2 The particle size is 100nm, and the mass ratio of the Fe-F-O compound is 8 ₂ 、FeF ₃ And Fe ₃ O ₄ The average particle size of the composition is 100nm, the heteroatom doped carbon material is a boron, nitrogen, sulfur and phosphorus co-doped composite carbon material, the atomic ratio of boron, nitrogen, sulfur and phosphorus is 0.5.

The mass of the coated composite material is 100%, the content of the inner core of the electrode material in the coated composite material is 94.4%, the mass of the Fe-F-O compound is 3%, the mass of the heteroatom doped carbon material is 0.5%, the mass of the carbon nano tube is 2%, and the mass of the amorphous carbon material is 0.1%.

The preparation method of the coated composite material comprises the following steps:

(1) Mixing boric acid, melamine, nitrilotriacetic acid, thiourea, mercaptan and adenosine triphosphate, transferring the mixture into a closed container, filling helium into the closed container, carrying out heat treatment on the closed container at 450 ℃ for 2 hours at the heating rate of 10 ℃/min, and cooling to obtain a heteroatom-doped carbon material;

(2) Mixing Li _1.1 Fe _0.6 V _0.3 O _1.8 F _0.2 Dispersing the Fe-F-O compound, the heteroatom doped carbon material and the single-walled carbon nanotube in ethylene glycol, and uniformly dispersing by ultrasonic; wherein the Fe-F-O compound is FeF with the mass ratio of 8 ₂ (brand I836769), feF ₃ (designation I836755) and Fe ₃ O ₄ (composition of the brand I903424);

(2) And (3) after the solution is spray-dried at the temperature of 100 ℃, carrying out heat treatment in an argon atmosphere, heating to 600 ℃ at the heating rate of 10 ℃/min for heat treatment for 0.5h, and cooling to obtain the coated composite material.

Example 3

The embodiment provides a coated composite material, which comprises an electrode material core and a coating layer coated on the surface of the electrode material core, wherein the coating layer comprises a Fe-F-O compound, a heteroatom doped carbon material, a carbon nanotube composite and an amorphous carbon material, and the electrode material core is Li _1.3 Mn _0.7 O _1.7 F _0.3 The particle size is 2000nm, and the mass ratio of the Fe-F-O compound is 8 ₃ 、Fe ₂ O ₃ And Fe ₃ O ₄ The average particle size of the composition is 50nm, the heteroatom doped carbon material is a boron, nitrogen, sulfur and phosphorus co-doped composite carbon material, the atomic ratio of boron, nitrogen, sulfur and phosphorus is 1.

The mass content of the core of the electrode material in the coated composite material is 92.5%, the mass content of the Fe-F-O compound in the coated composite material is 1%, the mass content of the heteroatom doped carbon material is 4%, the mass content of the carbon nano tube is 0.5%, and the mass content of the amorphous carbon material is 2%, wherein the mass content of the coated composite material is 100%.

(1) Mixing boric acid, nitrilotriacetic acid, thioether, hexachlorocyclotriphosphazene, polyvinylpyrrolidone, poly (4-vinylpyridine) and polyethylene glycol terephthalate, transferring the mixture into a closed container, filling nitrogen into the closed container, carrying out heat treatment on the closed container at 400 ℃ for 3 hours at the heating rate of 8 ℃/min, and cooling to obtain a heteroatom doped carbon material;

(2) Mixing Li _1.3 Mn _0.7 O _1.7 F _0.3 The Fe-F-O compound, the heteroatom doped carbon material and the multi-walled carbon nanotube are dispersed in the phenolic resin and uniformly dispersed by ultrasonic; wherein the Fe-F-O compound is FeF with the mass ratio of 8 ₃ (trade mark 011487), fe ₂ O ₃ (designation F299311) and Fe ₃ O ₄ (composition under the designation I119031);

(3) And (3) after the solution is spray-dried at the temperature of 250 ℃, carrying out heat treatment in a nitrogen atmosphere, heating to 300 ℃ at the heating rate of 1 ℃/min for heat treatment for 6h, and cooling to obtain the coated composite material.

Example 4

The embodiment provides a coated composite material, which comprises an electrode material core and a coating layer coated on the surface of the electrode material core, wherein the coating layerComprises Fe-F-O compound, heteroatom doped carbon material, carbon nanotube composite and amorphous carbon material, wherein the core of the electrode material is Li _1.1 Mn _0.8 V _0.05 Ni _0.05 O _1.9 F _0.1 The particle size is 500nm, and the mass ratio of the Fe-F-O compound to the FeF compound is 5 ₃ And Fe ₂ O ₃ The average particle size of the composition is 20nm, the heteroatom doped carbon material is a boron, nitrogen, sulfur and phosphorus co-doped composite carbon material, the atomic ratio of boron, nitrogen, sulfur and phosphorus is 1.

The content of the inner core of the electrode material in the coated composite material is 95.42% by mass, the content of the Fe-F-O compound in the coated composite material is 1.35% by mass, the content of the heteroatom doped carbon material is 1.8% by mass, the content of the carbon nano tube is 0.85% by mass, and the content of the amorphous carbon material is 0.58% by mass, based on 100% by mass of the coated composite material.

(1) Mixing boric acid, melamine, nitrilotriacetic acid, sodium thiosulfate, thiourea, mercaptan, dimethyl vinylphosphate, hexachlorocyclotriphosphazene and polyethylene glycol terephthalate, transferring into a closed container, filling argon and helium into the closed container, carrying out heat treatment on the closed container at 500 ℃ for 1h, wherein the heating rate of the heat treatment is 2 ℃/min, and cooling to obtain a heteroatom doped carbon material;

(2) Mixing Li _1.1 Mn _0.8 V _0.05 Ni _0.05 O _1.9 F _0.1 The Fe-F-O compound, the heteroatom doped carbon material and the multi-walled carbon nanotube are dispersed in glycerol and uniformly dispersed by ultrasonic; wherein the Fe-F-O compound is FeF with the mass ratio of 5 ₃ (designation I836755) and Fe ₂ O ₃ (composition under the designation F809546);

(3) And (3) spray-drying the solution at the temperature of 150 ℃, then carrying out heat treatment in an argon atmosphere, heating to 400 ℃ at the heating rate of 4 ℃/min for heat treatment for 4h, and cooling to obtain the coated composite material.

Example 5

The embodiment provides a coated composite material, which comprises an electrode material core and a coating layer coated on the surface of the electrode material core, wherein the coating layer comprises a Fe-F-O compound, a heteroatom-doped carbon material, a carbon nanotube composite and an amorphous carbon material, and the electrode material core is Li _1.2 V _0.7 Cr _0.1 O _1.98 F _0.02 The particle size is 400nm, and the mass ratio of the Fe-F-O compound is 5 ₂ 、FeF ₃ 、Fe ₂ O ₃ And Fe ₃ O ₄ The average particle size of the composition is 60nm, the heteroatom doped carbon material is a boron, nitrogen, sulfur and phosphorus co-doped composite carbon material, the atomic ratio of boron, nitrogen, sulfur and phosphorus is 0.5.

The mass content of the core of the electrode material in the coated composite material is 94.3%, the mass content of the Fe-F-O compound in the coated composite material is 1%, the mass content of the heteroatom doped carbon material is 1.5%, the mass content of the carbon nano tube is 2%, and the mass content of the amorphous carbon material is 1.2%, wherein the mass content of the coated composite material is 100%.

(1) Mixing boric acid, melamine, sodium thiosulfate, vinyl dimethyl phosphate and polyvinylpyrrolidone, transferring the mixture into a closed container, filling nitrogen, argon and helium into the closed container, carrying out heat treatment on the closed container at 350 ℃ for 4 hours at the heating rate of 4 ℃/min, and cooling to obtain a heteroatom-doped carbon material;

(2) Mixing Li _1.2 V _0.7 Cr _0.1 O _1.98 F _0.02 The Fe-F-O compound, the heteroatom doped carbon material and the multi-walled carbon nanotube are dispersed in ethylene glycol and uniformly dispersed by ultrasonic; wherein the Fe-F-O compound is FeF with the mass ratio of 5 ₂ (brand I836755), feF ₃ (designation I836755), fe ₂ O ₃ (designation F809546) and Fe ₃ O ₄ (composition of the brand I903421);

(3) And (3) after the solution is spray-dried at the temperature of 180 ℃, carrying out heat treatment in a helium atmosphere, heating to 500 ℃ at the heating rate of 8 ℃/min for 5h, and cooling to obtain the coated composite material.

Example 6

The embodiment provides a coated composite material, which comprises an electrode material core and a coating layer coated on the surface of the electrode material core, wherein the coating layer comprises a Fe-F-O compound, a heteroatom doped carbon material, a carbon nanotube composite and an amorphous carbon material, and the electrode material core is Li _1.2 V _0.7 Cr _0.1 O _1.99 F _0.01 The particle size is 1600nm, and the mass ratio of the Fe-F-O compound is 8 ₃ And Fe ₃ O ₄ The average particle size of the composition is 50nm, the heteroatom doped carbon material is a boron, nitrogen, sulfur and phosphorus co-doped composite carbon material, the atomic ratio of boron, nitrogen, sulfur and phosphorus is 1.

The mass content of the core of the electrode material in the coated composite material is 93.2%, the mass content of the Fe-F-O compound in the coated composite material is 2%, the mass content of the heteroatom doped carbon material is 2.5%, the mass content of the carbon nano tube is 1.5%, and the mass content of the amorphous carbon material is 0.8%, wherein the mass content of the coated composite material is 100%.

(2) Mixing Li _1.2 V _0.7 Cr _0.1 O _1.99 F _0.01 The Fe-F-O compound, the heteroatom doped carbon material and the multi-walled carbon nanotube are dispersed in the phenolic resin and uniformly dispersed by ultrasonic; wherein Fe-F-O is combinedThe product is FeF with the mass ratio of 8 ₃ (designation I836755) and Fe ₃ O ₄ (composition of the brand I903421);

(3) And (3) spray-drying the solution at 160 ℃, then carrying out heat treatment in a helium atmosphere, heating to 450 ℃ at a heating rate of 4 ℃/min for 1.5h, and cooling to obtain the coated composite material.

Example 7

This example provides a coated composite material and a method for producing the same, which are the same as those of example 1 except that the spray drying in step (3) is replaced with the ordinary drying.

Example 8

This example provides a clad composite and a method for preparing the same as in example 1, except that the temperature of the heat treatment in step (3) was 200 ℃.

Example 9

This example provides a clad composite and a method for preparing the same as example 1, except that the temperature of the heat treatment in step (3) was 700 ℃.

Example 10

This example provides a coated composite material and a method for preparing the same, except for Li in the coated composite material _1.2 Mo _0.7 Ti _0.1 O _1.8 F _0.2 The particle diameter of (2) was not more than 50nm, and the same as in example 1 was repeated.

Example 11

This example provides a coated composite material and a method for preparing the same, except for Li in the coated composite material _1.2 Mo _0.7 Ti _0.1 O _1.8 F _0.2 Has a particle diameter of 3000nm.

Example 12

This example provides a coated composite material and a method for preparing the same, except that the particle size of the Fe-F-O compound in the coated composite material is 200nm, as in example 1.

Example 13

This example provides a coated composite material and a method for preparing the same, as in example 1, except that the aspect ratio of the carbon nanotubes in the coated composite material is 200.

Example 14

This example provides a coated composite material and a method for preparing the same, except that the aspect ratio of the carbon nanotubes in the coated composite material is 4000, the same as in example 1.

Example 15

The embodiment provides a cladding composite material and a preparation method thereof, and the cladding composite material is the same as the cladding composite material in the embodiment 1 except that the atomic ratio of boron, nitrogen, sulfur and phosphorus in the heteroatom doped carbon material is 1.7.

Example 16

The present embodiment provides a coated composite material and a preparation method thereof, except that the atomic ratio of boron, nitrogen, sulfur, and phosphorus in the heteroatom-doped carbon material is 0.8.

Example 17

Example 18

The embodiment provides a cladding composite material and a preparation method thereof, and the cladding composite material is the same as the embodiment 1 except that the atomic ratio of boron, nitrogen, sulfur and phosphorus in the heteroatom doped carbon material is 0.8.

Example 19

This example provides a coated composite material and a method for preparing the same, except that the atomic ratio of nitrogen, sulfur and phosphorus in the heteroatom-doped carbon material is 1.5.

Example 20

This example provides a coated composite material and a method for preparing the same, except that the atomic ratio of boron, sulfur and phosphorus in the heteroatom-doped carbon material is 0.8.

Example 21

The embodiment provides a cladding composite material and a preparation method thereof, and the cladding composite material is the same as the embodiment 1 except that the atomic ratio of boron, nitrogen and phosphorus in the heteroatom doped carbon material is 0.8.

Example 22

The embodiment provides a cladding composite material and a preparation method thereof, and the cladding composite material is the same as the embodiment 1 except that the atomic ratio of boron, nitrogen and sulfur in the heteroatom doped carbon material is 0.8.

Example 23

This example provides a coated composite material and a method for preparing the same, except that the content of the Fe — F — O compound in the coated composite material is 6%, the same as in example 1.

Example 24

This example provides a coated composite material and a method for preparing the same, except that the content of the heteroatom-doped carbon material in the coated composite material is 8%, the rest is the same as that in example 1.

Example 25

This example provides a coated composite material and a method for preparing the same, except that the carbon nanotube content in the coated composite material is 4%, the same as in example 1.

Comparative example 1

This comparative example provides a coated composite material and a method for producing the same as in example 1 except that the coated composite material does not contain the Fe-F-O compound.

Comparative example 2

This comparative example provides a coated composite material and a method for producing the same as in example 1 except that the coated composite material does not contain a heteroatom-doped carbon material.

Comparative example 3

This comparative example provides a coated composite material and a process for producing the same as those in example 1, except that the coated composite material does not contain the multi-walled carbon nanotube.

Comparative example 4

This comparative example provides a coated composite material and a process for producing the same as in example 1, except that glycerol was replaced with deionized water in step (2).

The coating layer of the coated composite material prepared by the comparative example does not contain amorphous carbon.

Electrochemical performance tests are carried out on the coated composite materials provided in examples 1-25 and comparative examples 1-4, and the pole piece ratio is that the coated composite material, the mass ratio of acetylene black to PVDF is 90. 1mol/L LiPF with metal lithium sheet as counter electrode and polypropylene microporous membrane Celgard 2400 as diaphragm ₆ The volume ratio of/EC + DEC + DMC (1. And (3) performing constant-current charge and discharge test on the battery by adopting a LAND battery test system: the voltage range is 1.5-5.0V, the current density is 50mA/g and 200mA/g respectively, the capacity retention rate is obtained by testing the charge-discharge cycle for 200 circles under the current density of 50mA/g, and the test results are shown in Table 1.

TABLE 1

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The rate performance was characterized by the capacity tested at 50mA/g and 200mA/g current densities.

It can be seen from the above examples 1-25 that the cycling stability, reversible specific capacity, rate capability and first coulombic efficiency of the electrode material can be improved by the synergistic effect of the Fe-F-O compound, the heteroatom doped carbon material, the carbon nanotube and the amorphous carbon to construct the coating layer.

It can be known from the comparison between the embodiment 1 and the embodiment 7 that when the coated composite material is prepared by the method provided by the invention, spray drying is an optimal drying mode, and the coated composite material can play a role in granulation while being dried, so that uniform coating is realized, particle agglomeration is reduced, and the comprehensive electrochemical performance is improved.

As can be seen from the comparison between example 1 and examples 8-9, the heat treatment temperature in step (3) affects the electrochemical properties of the material, and the heat treatment temperature has a preferred range, and when the heat treatment temperature is too low, the solvent cannot be completely carbonized, and the effects of bonding particles and conducting electricity cannot be achieved; when the heat treatment temperature is too high, crystal grains grow along with the heat treatment temperature, and a lithium ion diffusion path is enlarged.

As can be seen from the comparison between example 1 and examples 10-11, the particle size of the core of the positive electrode material in the coated composite material affects the electrochemical performance of the material, when the particle size is smaller, agglomeration is easily caused, and the particle size difference between the core and the outer layer is too small, so that a uniform coating layer is difficult to form on the core of the positive electrode material, and the electrochemical performance, particularly the first coulombic efficiency and the cycle performance are reduced; when the particle size is larger, the electrochemical activity is reduced, resulting in a reduction in the overall electrochemical performance of the electrode material.

It is understood from a comparison between example 1 and example 12 that when the particle size of the Fe — F — O compound in the coated composite material is too large, the particle activity is lowered, and it is difficult to form a uniform coating layer, resulting in a decrease in electrochemical performance of the coated composite material.

As can be seen from the comparison between example 1 and examples 13-14, when the aspect ratio of the carbon nanotubes in the coated composite material is too short, a long-range conductive path cannot be formed, which is not favorable for constructing a stable material structure, and leads to the reduction of electrochemical performance, especially cycle performance; when the length-diameter ratio is too long, winding occurs, a uniform coating structure is difficult to form, and the electrochemical performance of the electrode material is reduced.

It can be seen from the comparison between example 1 and examples 15-18 that the heteroatom-doped carbon material has an optimal ratio of atoms of boron, nitrogen, sulfur and phosphorus, and an excessively large or excessively small ratio affects the microstructure of the heteroatom-doped carbon material, affects the electronic conductivity of the heteroatom-doped carbon material, and further affects the electrochemical performance of the electrode material.

It is understood from comparison between example 1 and examples 19 to 22 that the doping type of the heteroatom in the heteroatom-doped carbon material affects the electrochemical performance of the cathode material, and that the heteroatoms have a synergistic effect, and the effect of the present invention cannot be achieved in the absence of atoms.

It can be seen from the comparison between example 1 and examples 23-25 that the contents of the Fe-F-O compound, the heteroatom-doped carbon material and the carbon nanotubes in the coated composite material affect the electrochemical performance of the material, and when the coating content is too high, the transmission of lithium ions between interfaces is hindered, and the specific capacity of the whole material is reduced.

It is understood from the comparison between example 1 and comparative examples 1 to 3 that the absence of the Fe — F — O compound, the heteroatom-doped carbon material, and the carbon nanotube in the coating layer of the positive electrode material all have a bad effect on the electrochemical performance of the positive electrode material, and the expected result can be obtained only when the Fe — F-O compound, the heteroatom-doped carbon material, and the carbon nanotube are contained together.

It can be known from comparison of example 1 and comparative example 4 that the type of the solvent in step (2) affects the electrochemical performance of the material, and the solvent such as glycerol selected by the invention has certain viscosity, so that the effect of uniformly dispersing the particles can be realized, and simultaneously, the solvent can be carbonized to generate amorphous carbon in the heat treatment process, so that uniform coating is realized, and the function of bonding the particles is achieved. After glycerol is replaced by deionized water, the circulation stability and rate capability of the obtained electrode material are reduced because amorphous carbon cannot be provided.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention disclosed herein fall within the scope and disclosure of the present invention.

Claims

1. The coated composite material is characterized by comprising an electrode material core and a coating layer coated on the surface of the electrode material core, wherein the coating layer comprises an Fe-F-O compound, a heteroatom doped carbon material, a carbon nanotube compound and an amorphous carbon material;

the electrode material core is a positive electrode material core, the positive electrode material core is of a disordered cubic rock salt structure, and the Fe-F-O composition is FeF ₂ 、FeF ₃ 、Fe ₂ O ₃ And Fe ₃ O ₄ The composition formed, the heteroatom-doped carbon material is a boron, nitrogen, sulfur and phosphorus co-doped carbon material.

2. The clad composite material as claimed in claim 1 wherein the chemical formula of the disordered cubic rock salt structure positive electrode material core is Li _1+x M _1-x O _2-y F _y Wherein x is more than or equal to 0.1 and less than or equal to 0.3, y is more than 0 and less than or equal to 0.3, and M is a transition metal element.

3. The clad composite of claim 2 wherein the transition metal element is any one or a combination of at least two of Mn, ni, V, mo, fe, ti, zr, cr, co, cu, zn, nb, sc, or Y.

4. The clad composite of claim 3 wherein the transition metal element is any one or a combination of at least two of Mn, ni, V, mo, fe or Ti.

5. The clad composite of claim 1 wherein the boron, nitrogen, sulfur and phosphorus co-doped carbon material has an atomic ratio of boron, nitrogen, sulfur and phosphorus of (0.5-1): (1-2): (0.5-1).

6. The coated composite of claim 1 wherein the carbon nanotubes are single-walled carbon nanotubes and/or multi-walled carbon nanotubes.

7. The clad composite of claim 6 wherein said carbon nanotubes are multi-walled carbon nanotubes.

8. The coated composite of claim 1 wherein the carbon nanotubes have an aspect ratio of 500 to 3000.

9. The coated composite material of claim 8 wherein the carbon nanotubes have an aspect ratio of 1000 to 2000.

10. The clad composite of claim 1 wherein the particle size of the electrode material core is 100-2000nm.

11. The clad composite of claim 10 wherein the particle size of the electrode material core is 300-1000nm.

12. The clad composite of claim 1 wherein the Fe-F-O compound has a particle size of 20 to 100nm.

13. The clad composite of claim 1 wherein the electrode material core is present in an amount of 82-98.4% by mass of the clad composite taken as 100%.

14. The clad composite of claim 13 wherein the content of the electrode material core is 90-97% by mass of the clad composite as 100%.

15. The clad composite of claim 1 wherein the Fe-F-O compound is present in an amount of 0.5 to 5% based on 100% by mass of the clad composite.

16. The clad composite of claim 15 wherein the Fe-F-O compound is present in an amount of 1 to 3% based on 100% by mass of the clad composite.

17. The clad composite of claim 1 wherein the heteroatom-doped carbon material is present in an amount of 0.5 to 4% based on 100% by mass of the clad composite.

18. The clad composite of claim 17 wherein the heteroatom-doped carbon material is present in an amount of 1-3% based on 100% by mass of the clad composite.

19. The coated composite material according to claim 1, wherein the content of the carbon nanotube is 0.5 to 5% by mass of the coated composite material as 100%.

20. The coated composite material according to claim 19, wherein the carbon nanotube is contained in an amount of 0.5 to 2% by mass based on 100% by mass of the coated composite material.

21. The clad composite according to claim 1, wherein the amorphous carbon material is contained in an amount of 0.1 to 4% based on 100% by mass of the clad composite.

22. The clad composite of claim 21 wherein the amorphous carbon material is present in an amount of 0.5 to 2% based on 100% by mass of the clad composite.

23. The clad composite of claim 1 wherein the FeF is present in an amount of 100% by mass of the Fe-F-O composition ₂ And FeF ₃ The content of (A) is 70-90%.

24. The clad composite material as claimed in claim 1, wherein the clad layer is clad on a part of or the whole surface of the electrode material core.

25. A method of making the clad composite material of any one of claims 1-24 comprising the steps of:

26. The method according to claim 25, wherein the heteroatom-doped carbon material of step (1) is prepared by:

uniformly mixing boric acid, a nitrogen source, a sulfur source, a phosphorus source and a carbon source, and transferring the mixture into a closed container, wherein protective gas is filled in the closed container; and carrying out heat treatment on the closed container in the atmosphere of protective gas, and cooling to obtain the heteroatom doped carbon material.

27. The method according to claim 26, wherein the nitrogen source is melamine and/or nitrilotriacetic acid.

28. The method of claim 26, wherein the sulfur source is any one of sodium sulfide, sodium thiosulfate, thiourea, thiol, thiophenol, thioether, disulfide, polysulfide or cyclic sulfide or a combination of at least two thereof.

29. The method of claim 26, wherein the phosphorus source is any one or a combination of at least two of phosphonitrilic trichloride, adenosine triphosphate, adenosine diphosphate, phosphoenone pyruvic acid, phosphate esters, tetrakis (hydroxymethyl) phosphonium chloride, dimethyl vinylphosphate, hexachlorocyclotriphosphazene, polydichlorophosphazene, polyalkoxyphosphazene, polyaryloxy phosphazene, or polyfluorooxyphosphazene.

30. The method of claim 26, wherein the carbon source is any one of polyvinylpyrrolidone, poly (4-vinylpyridine), or polyethylene terephthalate, or a combination of at least two thereof.

31. The method according to claim 26, wherein the gas in the protective gas comprises any one of nitrogen, argon and helium or a combination of at least two of nitrogen, argon and helium in the method for preparing the heteroatom-doped carbon material.

32. The method according to claim 26, wherein the heat treatment is performed at a temperature of 350 to 500 ℃ in the method for producing the heteroatom-doped carbon material.

33. The method according to claim 26, wherein the heat treatment is performed for 1 to 4 hours in the heteroatom-doped carbon material.

34. The method according to claim 26, wherein in the method for producing a heteroatom-doped carbon material, the temperature increase rate of the heat treatment is 2 to 10 ℃/min.

35. The method of claim 25, wherein the mixing of step (1) is performed in the following manner: dispersing the electrode material inner core, the Fe-F-O compound, the heteroatom doped carbon material and the carbon nano tube in an organic solution, and performing ultrasonic dispersion uniformly.

36. The method of claim 35, wherein the organic solution is any one of ethylene glycol, glycerol, or a phenolic resin or a combination of at least two thereof.

37. The method of claim 35, wherein the power of the ultrasound is 150-250W, and the time of the ultrasound is 20-60min.

38. The method of claim 25, wherein the drying of step (2) is spray drying.

39. The method of claim 38, wherein the spray-dried exit temperature is from 100 ℃ to 250 ℃.

40. The method according to claim 25, wherein the heat treatment of step (2) is performed under a protective atmosphere.

41. The method according to claim 40, wherein the gas in the protective atmosphere in step (2) is any one of nitrogen, argon or helium or a combination of at least two of nitrogen, argon or helium.

42. The method of claim 25, wherein the temperature of the heat treatment of step (2) is 300-600 ℃.

43. The method as set forth in claim 25, wherein the temperature rise rate of the heat treatment of the step (2) is 1 to 10 ℃/min.

44. The method of claim 25, wherein the heat treatment of step (2) is performed for a holding time of 0.5 to 6 hours.

45. The method according to claim 44, wherein the heat treatment of step (2) is carried out for a holding time of 1 to 4 hours.

46. The method of any one of claims 25-45, wherein the method comprises the steps of:

(2) Dispersing an electrode material inner core, an Fe-F-O compound, a heteroatom doped carbon material and a carbon nano tube in an organic solution, and performing ultrasonic dispersion uniformly to obtain a mixed solution;

47. A lithium ion battery comprising the coated composite of any one of claims 1-24.