WO2013029212A1

WO2013029212A1 - Lithium-ion battery negative electrode material, preparation method therefor, and lithium-ion battery

Info

Publication number: WO2013029212A1
Application number: PCT/CN2011/002025
Authority: WO
Inventors: 岳敏; 闫慧青; 邓明华; 黄友元
Original assignee: 深圳市贝特瑞新能源材料股份有限公司
Priority date: 2011-09-03
Filing date: 2011-12-02
Publication date: 2013-03-07
Also published as: JP6021912B2; KR101768019B1; CN102299308A; JP2014524636A; KR20140030319A; CN102299308B; KR20160128445A

Abstract

Disclosed are a lithium-ion battery negative electrode material, a preparation method therefor, and a lithium-ion battery, where the technical problem to be solved is to improve for the lithium-ion battery the discharge capacity, discharge rate, and the performance in liquid-absorption and in cycling. The negative electrode material of the present invention is a composite material consisting of graphite substrates, networked carbon nanotubes and/or carbon nanofibers grown in situ on the graphite substrates, and/or networked carbon nanotubes and/or carbon nanofibers mixed between the graphite substrates, and nano-columnar structures. The preparation method of the present invention comprises: adding a catalyst into a graphite substrate material, placing same into a furnace chamber, and introducing a carbon source gas when the temperature reaches between 300°C and 1300°C. Compared with the prior art, the present invention allows for simplified process, precise and accurate control, facilitated reproduction, increased material specific surface area, improved electrical conductivity, an increase between 10 and 30 mAh/g in discharge capacity, and a 10C/1C ratio of ≥ 94%. Employment of the material of the present invention in the preparation of batteries reduces the amount of a conductive agent used and reduces costs for the lithium-ion battery.

Description

Lithium ion battery anode material and preparation method thereof, lithium ion battery

Technical field

The invention relates to a battery anode material, a preparation method thereof, and a battery using the anode material, in particular to a lithium ion battery composite carbon anode material, a preparation method thereof, and a lithium ion battery using the anode material.

Background technique

With the miniaturization of various portable electronic devices and the rapid development of electric vehicles, higher performance requirements have been proposed for lithium ion batteries as chemical power sources. The improvement in the performance of lithium ion batteries depends mainly on the improvement of the electrochemical properties of the electrode materials. The electrochemical properties of the electrode material can be improved by modifying it. Commonly used modification methods include surface-coated structure core-shell structure, doping modification, and surface oxidation. The existing carbon coating method can improve the electrochemical performance of the material to a certain extent, but the coating layer is thick and the wettability of the electrolyte is poor, which further affects the electrochemical performance of the anode material. When the electrode sheet is fabricated, a conductive agent is added, and during the lithium-intercalation cycle, the volume of the electrode material changes, so that the contact between the electrode material particles and the current collector after the charge-discharge cycle is poor, forming an "island". The effect causes the conductive network between the electrode material, the conductive agent carbon black and the current collector to be destroyed and the resistance to increase, and the cycle performance of the battery is degraded.

Summary of the invention

The object of the present invention is to provide a lithium ion battery anode material, a preparation method thereof, and a lithium ion battery, and the technical problem to be solved is to improve the charge and discharge capacity, rate performance and liquid absorption performance of the lithium ion battery, and have excellent cycle performance. , reduce battery expansion.

The present invention adopts the following technical solutions: a lithium ion battery anode material, the lithium ion battery anode material, a graphite matrix, mesh carbon nanotubes and/or carbon fibers grown in situ on the surface of the graphite substrate, and/or mixed in The composite carbon nanotubes and/or carbon fibers are composed of a graphite matrix, and the crystal layer spacing d _{002 of the} composite material is between 0.3356 and 0.347 nm, and the specific surface area is between 1 and 20 m ² /g; the network carbon nanometer The mass of the tube and the network carbon fiber is 0.1 to 15% of the mass of the graphite matrix; the reticulated carbon nanotubes and the reticulated carbon fibers have an average diameter of 100 to 500 nm and an average length of 5 to 100 μm.

A method for preparing a negative electrode material for a lithium ion battery comprises the following steps: 1. adding a catalyst having a mass of graphite matrix of more than 0 to 5% in a graphite matrix material to obtain a mixture; the graphite matrix has a carbon content of 85 More than one of natural flake graphite, microcrystalline graphite, artificial graphite, carbon microspheres, and conductive graphite, one or more of a spherical shape, a block shape, and a sheet shape having a spherical shape and a length-to-minor axis ratio of 1.0 to 4.5. The particle size D ₅₀ is 3-40 μm; the catalyst is: a nitrate, a sulfate, a halide or an oxide of iron, cobalt or nickel; 2. The mixture is placed in a furnace chamber at a rate of 0.1 to 50 ° C/min. When the temperature is raised, the protective gas nitrogen or argon gas is introduced at a flow rate of 0.05 to 10 m ³ /h. When the temperature reaches 300 to 1300 ° C, the carbon source gas is introduced at a flow rate of 0.05 to 10 m ³ /h, and the passage time is 0.1～5h; the carbon source gas is methane, acetylene, ethylene, CO ₂ , natural gas, liquefied petroleum gas, benzene or thiophene; 3. cooling water is introduced between the furnace wall and the heat conducting layer in the furnace wall to cool Way or natural cooling method in the furnace to 100 The following four; at a heating rate of 0.5 ~ 50 ° C / min, the temperature is raised to 300 ~ 3000 ° C, heat preservation 0.5 ~ 10h; 5, using the cooling water between the furnace wall and the furnace wall to cool the way Or the natural cooling mode in the furnace is below 100 °C, and the protective gas nitrogen or argon gas is stopped to obtain the negative electrode material of the lithium ion battery.

The catalyst to be added of the present invention employs solid phase mixing or liquid phase mixing.

The solid phase mixing of the present invention is mechanically mixed by a high-speed modified mixer, a conical mixer or a ball mill, and mixed at a rotational speed of 500 to 5000 r/min for 5 to 180 minutes.

The liquid phase mixing of the present invention is mixed by a high speed mixer or a sol gel, and mixed and stirred at a speed of 500 to 8000 rpm for 5 to 180 minutes. The solvent used is water or an organic solvent, and the organic solvent is anhydrous ethylene glycol or glycerol. , isopropanol or acetone, tetrahydrofuran, N-methylpyrrolidone NMP or dimethylacetamide, the mass of the solvent is 0.1 to 3.0 times the mass of the graphite matrix, the mixing temperature is 10 to 90 ° C, and then a spray dryer is used. Dry with a suction filter or a freeze dryer.

The spray drying inlet temperature of the present invention is 150 to 350 ° C, the outlet temperature is 50 to 150 ° C, and the pressure is 10 to 100 Pa.

The invention puts the mixture into the furnace cavity of the rotary furnace, the tube furnace and the carbon tube furnace, and the volume of the mixture is 0.1-50% of the furnace capacity, and the furnace chamber is rotated at a rotation speed greater than 0 to 20 rpm.

In the present invention, the mixture is placed in a furnace chamber and heated at a rate of 0.1 to 50 ° C / min. When the temperature reaches 300 to 1300 ° C, the temperature is maintained for more than 0 to 0.5 h, and then the flow rate is 0.05 to 10 m ³ /h. Into the carbon source gas.

After the invention stops the introduction of the carbon source gas, it is maintained at 300 to 1300 ° C for more than 0 to 6 h.

The lithium ion battery anode material adopts heating under 100° C., vacuum drying or other prior art to control the moisture content thereof to be less than 0.1%, and then sieving, demagnetizing, and demagnetizing times of 1 to 10 times. The magnetic induction intensity is 3,000 to 30,000 Gs, the treatment temperature is 10 to 80 ° C, and the number of electromagnetic hammer strikes is 3 to 180 / sec, and a lithium ion battery negative electrode material having an average particle size D ₅₀ of 3 to 50 μm is obtained.

A lithium ion battery anode material, wherein the lithium ion battery anode material is composed of a graphite matrix and a nano columnar and/or nanoparticle structure in which the surface is grown in situ; the graphite matrix is a natural stone having a carbon content of 85% or more. Ink, natural flake graphite, microcrystalline graphite, artificial graphite, carbon microspheres or conductive graphite, having a spherical, spheroidal, massive and/or sheet-like morphology with a spherical to long-axis ratio of 1.0 to 4.5, and a particle size of D ₅₀ 3 to 40 um; the nano-columnar and/or nano-granular structure is a disordered crystal, and the nano-columnar and/or nano-granular structure has a mass of 0.05 to 10% of the mass of the graphite matrix.

A method for preparing a negative electrode material for a lithium ion battery comprises the following steps: 1. heat treatment, heat treating the graphite substrate at a heating rate of 1 to 20 ° C / min to a temperature of 300 to 3000 ° C in a protective gas nitrogen or argon atmosphere 1 ~ 144 h, then the furnace naturally cools to below 100 ° C; the graphite matrix material is more than 85% carbon natural graphite, natural flake graphite, microcrystalline graphite, artificial graphite, carbon microspheres or conductive graphite, particle size For D ₅₀ is 3-40 um; second, mixing, adding a catalyst having a mass of graphite matrix of more than 0 to 5% in the graphite matrix, using solid phase mixing or liquid phase mixing to obtain a mixture; the catalyst is: iron, a nitrate, a sulfate, a halide or an oxide of cobalt or nickel; three, vapor deposition, the mixture is placed in a furnace chamber, heated at a rate of 0.1 to 50 ° C / min, and passed through a flow rate of 0.1 to 10 m ³ /h. The protective gas nitrogen or argon gas is maintained at a temperature of 300 to 1300 ° C for 0.1 to 0.5 h, and a carbon source gas is introduced at a flow rate of 0.1 to 10 m ³ /h, and the introduction time is 0.1 to 4 h; source gas is methane, acetylene, ethylene, CO ₂ Natural gas, liquefied petroleum gas, benzene or thiophene; Fourth, heat preservation, maintained at 300 ~ 1300 ° C for 0.5 ~ 6h; Fifth, using compressed air between the furnace wall and the furnace wall to reduce the temperature or The natural cooling method in the furnace is below 100 ° C, and the protective gas nitrogen or argon gas is stopped to obtain a negative electrode material for the lithium ion battery.

The protective gas of the present invention has a nitrogen or argon atmosphere and a gas flow rate of 0.5 to 20 m ³ /h.

In the heat treatment of the present invention, the volume of the graphite matrix accounts for 1 to 50% of the capacity of the furnace.

The graphite matrix of the invention is added with a catalyst having a mass of graphite matrix of more than 0 to 5%, and the solid phase mixing method is adopted, and the rotation speed is 100-3000. r/min, the treatment time is 5 to 200 min, and the treatment temperature is 20 to 80 °C.

The graphite matrix of the invention is added with a catalyst having a mass of graphite matrix of more than 0 to 5% by mass mixing, wherein the solid mass is 10-70% of the total mass of the solid and the liquid, and the rotation speed is 600-3000 r/min. The mixing time is 90-180 min, the mixing temperature is 10-80 ° C, and the liquid phase is mixed and dried by a spray dryer, a suction filter or a freeze dryer to control the moisture content of the material to be less than 2%.

In the vapor deposition of the present invention, the mixture is placed in a furnace chamber of a rotary furnace, a tube furnace, and a carbon tube furnace, and the furnace chamber is rotated at a rotational speed of 5 to 20 rpm.

The negative electrode material of the lithium ion battery of the invention is firstly sieved and demagnetized, the magnetic removal is 1 to 10 times, the magnetic induction intensity is 3000 to 30000 Gs, the treatment temperature is 10 to 80 ° C, and the number of electromagnetic hammer strikes is 3 to 180 / second, and the particle size is obtained. The D ₅₀ is 3 to 50 um.

The heat treatment of the present invention is carried out by heat treatment at 300 to 3000 ° C for 1 to 144 hours.

In the vapor deposition of the present invention, the mixture is placed in a furnace chamber, heated at a rate of 0.1 to 50 ° C / min, and a protective gas such as nitrogen or argon is introduced at a flow rate of 0.1 to 10 m ³ /h, and the temperature reaches 300 to 1300. At °C, the carbon source gas is introduced at a flow rate of 0.1 to 10 m ³ /h for 0.1 to 0.5 h, and the introduction time is 0.1 to 4 hours.

A lithium ion battery comprising a negative electrode material comprising a graphite matrix, reticulated carbon nanotubes and/or nanocarbon fibers in situ on the surface of the graphite substrate, and/or reticulated carbon nanoparticles intercalated between the graphite substrates The tube and/or the nano carbon fiber, the nano-columnar and/or the nano-particle structure constitute a composite material, and the crystal layer spacing d _{002 of the} composite material is between 0.3356 and 0.347 nm, and the specific surface area is between 1 and 20 m ² /g; the reticulated carbon The mass of the nanotubes and the reticulated carbon fibers is 0.1 to 15% of the mass of the graphite matrix; the reticulated carbon nanotubes and the reticulated carbon fibers have an average diameter of 100 to 500 nm and an average length of 5 to 100 μm; the anode material is composed of a graphite matrix and The surface consists of nano-columnar and/or nano-particle structures grown in situ; the graphite matrix is natural graphite, natural flake graphite, microcrystalline graphite, artificial graphite, carbon microspheres or conductive graphite having a carbon content of more than 85%. a spheroidal, massive, and/or sheet-like topographical feature having a spherical, long-and short-axis ratio of 1.0 to 4.5, having a particle size D ₅₀ of 3 to 40 μm; and the nano-columnar and/or nano-particle structure being disordered crystals Na The columnar and/or nanoparticle structure mass is 0.05 to 10% of the mass of the graphite matrix.

Compared with the prior art, the invention adopts spherical flake, spheroidal, massive and/or flake-like natural flake graphite, microcrystalline graphite, artificial graphite, carbon microspheres and conductive graphite as matrix materials. Using a chemical vapor deposition method, in-situ growth of a carbon nanotube or nano-columnar having an amorphous structure of carbon or a layered structure of graphite on the surface of the base material, the process is simplified, the control is precise, the reproduction is easy, and the conduction is improved. The performance solves the "island" effect of the material in the process of lithium insertion and delithiation, improves the reversible capacity and rate performance of the anode material, and increases the discharge capacity by 10~30mAh/g, and the ratio performance of 10C/1C ratio ≥94%. The negative electrode material of the lithium ion battery of the invention has little influence on the structure of the active material of the lithium ion battery during the charging and discharging process, maintains the structural stability, greatly improves the cycle performance of the lithium ion battery, and uses the material of the invention to make the pole piece of the battery. The amount of the conductive agent in the process of fabricating the pole piece can be reduced, or the conductive electrode can be omitted, thereby further reducing the cost of the lithium ion battery.

DRAWINGS

1 is an SEM image of an electrode material of a reticulated carbon nanotube structure according to Embodiment 1 of the present invention.

2 is a cross-sectional SEM image of an electrode material of a reticulated carbon nanotube structure according to Embodiment 1 of the present invention.

3 is an SEM image of an electrode material of a nano-columnar structure according to Embodiment 7 of the present invention.

Fig. 4 is a graph showing different rate discharge curves of Example 7 of the present invention.

Figure 5 is a 10C rate discharge curve of Example 7 and Comparative Example 3 of the present invention.

detailed description

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The lithium ion battery anode material of the present invention is composed of a graphite matrix, reticulated carbon nanotubes and/or carbon fibers grown in situ on the surface of the graphite substrate, and/or mixed therein. The networked carbon nanotubes and/or carbon fibers between the graphite substrates constitute a composite material, and the crystal layer spacing d _{002 of the} composite material is between 0.3356 and 0.347 nm, and the specific surface area is between 1 and 20 m ² /g. The mass of the reticulated carbon nanotubes and the reticulated carbon fibers is 0.1 to 15% of the mass of the graphite matrix. The reticulated carbon nanotubes and the reticulated carbon fibers have an average diameter of 100 to 500 nm and an average length of 5 to 100 μm.

The graphite matrix is one or more kinds of natural flake graphite, microcrystalline graphite, artificial graphite, carbon microspheres and conductive graphite having a carbon content of 85% or more, and has a spherical shape and a spherical-like shape with a length-to-minor axis ratio of 1.0 to 4.5. one kind or more massive and sheet-like having a particle size D ₅₀ of 3 ~ 40μm.

The reticulated carbon nanotubes have the characteristics of an amorphous structure of carbon or a layered structure of graphite, and the reticulated carbon fibers have characteristics of an amorphous structure of carbon or a layered structure of graphite.

The first method for preparing the negative electrode material for a lithium ion battery of the present invention comprises the following steps:

1. Mixing, adding a catalyst to the graphite matrix material, the mass of the catalyst is more than 0 to 5% of the mass of the graphite matrix, and the mixture is mixed by solid phase or liquid phase to obtain a mixture. As a carbon source decomposition active center and a graphite carbon deposition center, the catalyst plays a vital role in the morphology and structure of the network of carbon nanotubes and/or carbon fibers formed on the surface of the graphite matrix by the cracking products of carbon on the surface of the graphite matrix. Good catalysts and other conditions of the invention allow for the formation of reticulated carbon nanotubes and carbon fiber structures.

The graphite matrix is more than one kind of natural flake graphite, microcrystalline graphite, artificial graphite, carbon microspheres and conductive graphite having a carbon content of more than 85%, and the spherical shape, the block shape and the shape of the spherical and long axis ratio of 1.0 to 4.5 One or more of the sheet forms have a particle size D ₅₀ of 3 to 40 μm.

The catalyst is: a nitrate, a sulfate, a halide or an oxide of iron, cobalt or nickel.

The solid phase mixing is mechanically mixed using a high speed modified VC mixer, a conical mixer or a ball mill. In this embodiment, a VC-150/VC-500 mixer of Wuxi Xinguang Powder Processing Technology Co., Ltd. is used, and the mixture is mixed at a speed of 500 to 5000 r/min for 5 to 180 minutes.

The liquid phase mixing is carried out by mixing with a high speed mixer or a sol gel, followed by drying using a spray dryer, a suction filter or a freeze dryer. The graphite matrix material is mixed with the catalyst liquid phase. In this embodiment, the GX-200 high-speed mixer of Wuxi Xinguang Powder Processing Technology Co., Ltd. is used, and the mixture is stirred at a speed of 500-8000 r/min for 5 to 180 minutes. The solvent used is water or The organic solvent is an anhydrous ethylene glycol, glycerin, isopropanol or acetone, tetrahydrofuran, N-methylpyrrolidone NMP or dimethylacetamide, and the mass of the solvent is 0.1 to 3.0 times the mass of the graphite matrix. The mixing temperature is 10～90°C; the gas phase is dried by GZ-500 high-speed centrifugal spray dryer of Wuxi Sunshine Drying Equipment Factory. The inlet temperature is 150-350°C, the outlet temperature is 50-150°C, and the pressure is 10 to 100 Pa, the feed flow rate is 150 to 1000 kg/h.

Second, vapor deposition, the mixture is placed in the furnace chamber of the rotary furnace, tube furnace, carbon tube furnace, the volume of the mixture is 0.1 to 50% of the furnace capacity, and the temperature is raised at a rate of 0.1 to 50 ° C / min, while 0.05 to 10 m 3 The flow rate of /h is passed through a protective gas such as nitrogen or argon, and the furnace chamber is rotated at a speed of 0 to 20 rpm. When the temperature reaches 300 to 1300 ° C, the flow rate is maintained at 0 to 0.5 h, and the flow rate is 0.05 to 10 m ³ /h. Into the carbon source gas, the introduction time is 0.1 ~ 5h, chemical vapor deposition of carbon, so that the surface of the graphite substrate grows in situ to obtain reticulated carbon nanotubes and / or carbon fibers, and / or grow between the graphite matrix to reticulate carbon nano Tube and / or carbon fiber.

The carbon source gas is methane, acetylene, ethylene, CO ₂ , natural gas, liquefied petroleum gas, benzene or thiophene.

3. Keep warm, stop the carbon source gas, keep at 0 ~ 6h under the condition of 300 ~ 1300 °C, and continue to pass the protective gas nitrogen or argon at a flow rate of 0.05 ~ 10m ³ / h. The role of this process is to prevent oxidation of residual carbon source gases, graphite matrix materials or reticulated carbon nanotubes and carbon fibers.

4. Cooling, using cooling water to reduce the temperature between the furnace wall and the heat conducting layer in the furnace wall or the natural cooling method in the furnace to below 100 °C. This process continues with a protective gas nitrogen or argon at a flow rate of 0.05 to 10 m ³ /h.

5. Heat treatment, with a heating rate of 0.5 to 50 ° C / min, and continue to pass the protective gas nitrogen or argon at a flow rate of 0.05 ~ 10 m ³ / h, the temperature is raised to 300 ~ 3000 ° C, and the temperature is maintained for 0.5 ~ 10h. By heat-treating the chemical vapor deposited graphite material, the structure of the reticulated carbon nanotubes and carbon fibers on the surface of the graphite substrate and between them can be adjusted, and the distribution of the reticulated carbon nanotubes and carbon fibers on the surface of the substrate is more uniform. At this time, the function of continuously feeding the protective gas is to remove the remaining impurity gas generated in the furnace chamber to prevent oxidation of the deposit on the graphite oxide base material.

6. Cooling, using cooling water between the furnace wall and the heat transfer layer in the furnace wall to cool down or the natural cooling method in the furnace to below 100 °C, stop the introduction of protective gas nitrogen or argon.

7. Screening and demagnetization, using 100 °C or less heating, vacuum drying or other prior art to control the moisture content of the negative electrode material below 0.1%, and then sieving, demagnetizing, demagnetization times 1-10 times, magnetic induction intensity It is 3000 to 30000 Gs, the treatment temperature is 10 to 80 ° C, the number of electromagnetic hammer strikes is 3 to 180 / sec, and the average particle size D ₅₀ is 3 to 50 μm, and a lithium ion battery anode material is obtained.

The method of the invention firstly selects natural flake graphite, microcrystalline graphite, artificial graphite, carbon microspheres and conductive graphite with a carbon content of only 85% of the raw materials, and the prior art coating preparation method needs to adopt a carbon content. High graphite material, so the method of the present invention greatly reduces the cost in the selection of raw materials.

Secondly, the prior art is applied to a negative electrode material of a lithium ion battery, and a composite negative electrode material is usually prepared by a modification treatment method such as doping or coating a raw material, but the preparation process is complicated, and the composition, morphology, size, and size of the control material are controlled. The accuracy of the thickness of the cladding layer is poor, which tends to cause uneven distribution of the composite anode material, which affects the improvement of electrochemical performance. The vapor deposition preparation method adopted by the invention has simple process, and can accurately control the in-situ growth process of the electrode material by controlling the concentration of the carbon source gas, the reaction time and the like, and prepare a negative electrode having good electrochemical performance. material.

The anode material of the lithium ion battery prepared by the method of the invention is observed by a Hitachi S4800 scanning electron microscope, and the crystal layer spacing is obtained by PW3040/60 X' Pert X-ray diffractometer of the Dutch PANalytical Instruments Company. The specific surface area was tested by a nitrogen displacement BET method. As shown in FIG. 1 and FIG. 2, the anode material of the lithium ion battery of the present invention is composed of a graphite matrix, reticulated carbon nanotubes and/or carbon fibers grown in situ on the surface of the graphite substrate, and/or mixed between the graphite substrates. Reticulated carbon nanotubes and/or carbon fibers, wherein the crystal layer spacing d _{002 is} between 0.3356 and 0.347 nm, and the specific surface area is between 1 and 20 m ² /g. The reticulated carbon nanotubes and carbon fibers are distributed on the surface of the graphite substrate. It is relatively uniform, has an average length of 5 to 100 μm, and has a relatively obvious tubular structure and an inner layered structure, and has an average diameter of 100 to 500 nm. As shown in FIG. 2, reticulated carbon nanotubes and/or carbon fibers are grown inside, and reticulated carbon nanotubes and/or carbon fibers have good electronic conductivity and ionic conductivity, so that the conductivity can be improved. At the same time, lithium ion batteries made of the negative electrode material can not only be embedded in the graphite layer, but also the mesh carbon nanotubes and/or carbon fibers can be embedded in a certain amount of lithium ions, thereby increasing the lithium insertion amount of the lithium ion battery. In addition, the reticulated carbon nanotubes and/or carbon fibers present on the outside and inside of the electrode material can act as a "fixing frame" during the insertion and removal of lithium ions, thereby reducing electrode expansion in the battery.

The method of the invention directly grows a composite anode material having a reticulated carbon nanotube and/or carbon fiber structure directly on the surface of the graphite substrate by a vapor deposition method, and the carbon nanotubes and the carbon fiber have complementary properties, and further optimizes the structure of the composite anode material. Due to the in-situ growth of the reticulated carbon nanotubes and the reticulated carbon fibers having a tubular opening structure and a graphite-like layered structure, lithium can be stored between the graphite layers, and the layer spacing d ₀₀₂ is 0.3356 to 0.347 nm, which is more than the graphite layer spacing. Large, is conducive to the deintercalation of lithium ions. After the in-situ growth of the reticulated carbon nanotubes and the reticulated carbon fiber structure of the composite anode material, the ion conduction path becomes shorter, so that the intercalation and extraction of lithium ions between the graphite layers are smoother, and the destruction of the graphite layer and the solvent are reduced. The insertion phenomenon improves the reversible lithium insertion capacity and cycle performance of the composite anode material.

The reticulated carbon nanotubes or carbon fibers on the surface of the negative electrode material of the lithium ion battery of the present invention are uniformly distributed, and have an average diameter of 100 to 500 nm, and the reticulated carbon nanotubes or carbon fibers grown in situ on the surface are interdigitated to form a disordered layer structure. The structure can not only improve the surface liquid absorbing property of the material, but also prevent the graphite layer from being peeled off due to the solvation of lithium ions embedded in the graphite matrix, thereby causing damage of the anode material, thereby improving the cycle performance of the mesh carbon nanotube-like electrode material.

The reticulated carbon nanotubes or reticulated carbon fibers involved in the present invention are directly grown in situ on the surface of the graphite substrate to form a surface structure, which provides a good passage for the insertion and extraction of lithium ions, and at the same time, the intercalation of lithium ions The path becomes shorter, the solid phase diffusion is accelerated, and the polarization becomes smaller, so the conductivity of the composite anode material is increased, and the charge and discharge performance and the rate performance are improved.

In the negative electrode material of the lithium ion battery of the invention, the graphite substrate is grown in situ to obtain a lithium ion battery anode material having a larger specific surface area (1-20 m ² /g) than the graphite matrix, and on the other hand, the electrode is made The current density is reduced, which reduces the polarization of the electrode; on the other hand, lithium ions provide more migration channels, shorten the migration path, and lower the diffusion resistance, thus improving the overall electrochemical performance of the composite anode material and performing Better rate performance.

The anode of the battery is prepared by using the anode material of the lithium ion battery of the invention, adding a binder, a thickener and a solvent, stirring and pulping, coating on the copper foil, and drying and milling. The binder used may be polyvinylidene fluoride PVDF dissolved in N-methylpyrrolidone, water-soluble styrene-butadiene rubber emulsion SBR, sodium carboxymethylcellulose CMC. The positive electrode material used may be various composite oxides containing lithium ions, such as LiCoO ₂ , LiNiO ₂ or LiMn ₂ O ₄ , the electrolyte used may be a general-purpose electrolyte and a solvent, and the electrolyte may be an inorganic electrolyte or an organic electrolyte. For example, LiClO ₄ , LiPF ₆ , LiAsF ₆ or LiBF ₆ , the solvent is generally composed of a mixture of a high dielectric constant carbocyclic olefin and a low viscosity chain hydrocarbon carboester, such as carbovinyl ester EC, carbo propylene. Ester PC, carboxy dimethyl ester DMC, cardicarboxylate DEC or carboxymethyl ethyl ester MEC. The separator may be a commercially available polyethylene PE, polypropylene PP or polyethylene propylene PEP composite film.

The anode material of the lithium ion battery prepared by the invention is used for the pole piece production of the electrode, and the composite anode material is composed of the graphite matrix material and the mesh carbon nanotubes and/or carbon fibers which are grown and/or mixed in situ in the graphite matrix material, and has good performance. The conductive property can reduce the amount of the conductive agent in the process of fabricating the pole piece, or can not add the conductive agent, thereby further reducing the manufacturing cost of the lithium ion battery.

The lithium ion battery anode material of the present invention is composed of a graphite matrix and a nano-columnar and/or nano-particle structure in which the surface is grown in situ. The graphite matrix is natural graphite, natural flake graphite, microcrystalline graphite, artificial graphite, carbon microspheres or conductive graphite having a carbon content of 85% or more, and has a spherical shape and a block shape with a spherical length to length ratio of 1.0 to 4.5. And/or sheet-like topography, the particle size is D ₅₀ of 3 to 40 um. The nano-columnar and/or nano-granular structures are disordered crystals. The nano-columnar and/or nano-grain structure has a mass of 0.05 to 10% of the mass of the graphite matrix.

The nano-columnar refers to directly growing nano-columnar carbon nanotubes or carbon fibers directly on the surface of the graphite substrate, and the average diameter is 1 to 500 nm, and the nano-particles refer to carbon nanotubes directly grown on the surface of the graphite substrate or The carbon fibers are granular, disordered carbon having an average diameter of 1 to 100 nm.

The second method for preparing the negative electrode material for a lithium ion battery of the present invention comprises the following steps:

A heat treatment, in 0.5 ~ 20m ³ / protective atmosphere h flow, a graphite substrate at 1 ~ 20 ℃ / temperature rise rate min., To 300 ~ 3000 ℃ heat 1 ~ 144 h, and then furnace natural cooling to 100 °C, the volume of the graphite matrix accounts for 1 to 50% of the furnace capacity.

The graphite base material is a carbon content of 85% or more of natural graphite, natural flake graphite, crystallite graphite, artificial graphite, conductive graphite or carbon microspheres, a particle size D ₅₀ of 3 ~ 40um.

The protective gas is nitrogen or argon.

2. Mixing, adding a catalyst to the heat-treated graphite matrix, the mass of the catalyst is more than 0 to 5% of the mass of the graphite matrix, and the mixture is obtained by solid phase mixing or liquid phase mixing.

The solid phase mixing adopts high-speed modified VC mixer, cone mixer and ball mill, and the rotation speed is 100-3000. r/min, the treatment time is 5 to 200 min, and the treatment temperature is 20 to 80 °C.

High-speed mixer for liquid phase mixing, the solid mass is 10-70% of the total mass of solid and liquid, the rotation speed is 600-3000r/min, the mixing time is 90-180min, the mixing temperature is 10-80°C, and the liquid phase is mixed. Drying by spray dryer, suction filter or freeze dryer to control the moisture content of the material below 2%.

The catalyst is: a nitrate, a sulfate, a halide or an oxide of iron, cobalt or nickel. The catalyst is added to decompose the active carbon center and the graphite carbon deposition center on the surface of the graphite substrate to control the morphology and structure of the carbon cracking product.

3. Vapor deposition, placing a mixture of graphite matrix and catalyst in a furnace chamber of a rotary furnace, raising the temperature at a rate of 0.1 to 50 ° C/min, and introducing a protective gas at a flow rate of 0.1 to 10 m ³ /h, to 5 to 5 The furnace chamber is rotated at a speed of 20 rpm. When the temperature reaches 300-1300 ° C, the temperature is maintained for 0.1 to 0.5 h, and at the same time, the carbon source gas is introduced at a flow rate of 0.1 to 10 m ³ /h, and the introduction time is 0.1 to 4 h.

The protective gas is nitrogen or argon.

The carbon source gas is methane, acetylene, ethylene, CO ₂ , natural gas, liquefied petroleum gas, benzene or thiophene. Used to grow in situ in the form of nano-columns on the surface of the graphite substrate.

4. Keep warm, stop the carbon source gas, keep it at 0.5~6h under the condition of 300～1300°C, and continue to pass the protective gas at a flow rate of 0.05～10m ³ /h.

The protective gas is nitrogen or argon.

5. The method of cooling the air between the furnace wall and the heat conducting layer in the furnace wall to reduce the temperature or the natural cooling in the furnace to 100 ° C or less is adopted, and the protective gas is stopped.

The protective gas is nitrogen or argon.

6. Screening and demagnetization, using 100 ° C or less heating, vacuum drying or other prior art to control the moisture content of the negative electrode material below 0.1%, and then sieving, demagnetizing, demagnetizing 1 to 10 times, magnetic induction intensity is 3000 to 30000 Gs, the treatment temperature is 10 to 80 ° C, the number of electromagnetic hammer strikes is 3 to 180 / sec, and the particle size is D ₅₀ is 3 to 50 um, and the package is obtained to obtain a lithium ion battery anode material.

The method of the present invention firstly selects natural flake graphite, microcrystalline graphite, artificial graphite, carbon microspheres or conductive graphite having a carbon content of 85% or more, and the prior art coating preparation method requires high carbon content. The graphite material, therefore, the method of the present invention greatly reduces the cost in the selection of raw materials.

The negative electrode material of the lithium ion battery prepared by the method of the present invention was observed by a scanning electron microscope of Hitachi Hitachi S4800-I. The resistivity of the lithium ion battery anode material was tested by FZ-9601 powder resistivity tester of Shanghai Hongyun Testing Instrument Co., Ltd. The higher the resistivity, the worse the conductivity of the material, and the lower the resistivity, the better the conductivity of the material. The mass of the nano carbon fiber is calculated to be 0.05 to 10% of the mass of the graphite matrix by calculation (the obtained composite material mass - graphite matrix mass) / graphite matrix mass).

The electrode pole piece prepared by using the anode material of the lithium ion battery prepared by the invention is composed of a graphite matrix and a nano columnar and/or nano particle structure in which the surface is grown in situ, and has good electrical conductivity, so that the process of manufacturing the pole piece can be reduced. The amount of the binder and the conductive agent may be omitted without adding a conductive agent, thereby further reducing the manufacturing cost of the lithium ion battery.

Example 1: A spherical natural graphite having a particle size D ₅₀ of 3 to 40 μm and a carbon content of 85% was placed in a VC-500 mixer, and a 5% catalyst Fe(NO ₃ ) ₃ solid phase was introduced, and the rotation speed was 500r/min, mixing time is 180min, the mixture is obtained; the mixture is placed in the furnace cavity of the rotary furnace, the volume of the mixture is 10% of the furnace capacity, and the nitrogen gas is introduced at a flow rate of 10 m ³ /h at a rate of 0.1 ° C / min. The temperature was raised to 1300 ° C, and the furnace cavity was rotated at 20 rpm for 0.5 h; then the carbon source gas methane was introduced at a flow rate of 10 m 3 /h, and the carbon source gas was stopped after 0.1 h (maintained at 1300 ° C for 0 h). ); cooling water is passed between the furnace wall and the heat conducting layer in the furnace wall to cool down to below 100 ° C; nitrogen gas is continuously applied at a flow rate of 10 m ³ /h, and the temperature is raised to 0.5 ° C / min to Maintained at 300 ° C for 10 h, naturally cooled to below 100 ° C, stop the introduction of nitrogen; the moisture content of the obtained composite material is controlled below 0.1%, and then sieved, demagnetization, demagnetization times 5 times, magnetic induction intensity is 10000Gs , the processing temperature is 10 ° C, the number of electromagnetic hammer strikes is 20 / sec; get the average A lithium ion battery anode material having a particle size D ₅₀ of 17.8 μm is packaged in a finished product. Tested by the BET method, the specific surface area was 20 m ² /g. Observed in the PW3040/60 X' Pert X-ray diffractometer of the Dutch PANalytical Instruments, as shown in Figure 1, reticulated carbon nanotubes and/or carbon fibers grown in situ on the surface of the graphite substrate, and/or mixed The reticulated carbon nanotubes and/or carbon fibers between the graphite substrates constitute a composite material, and the crystal layer spacing d _{002 of the} composite material is between 0.3356 and 0.347 nm. The mass of the reticulated carbon nanotubes and the reticulated carbon fibers is 11.3% of the mass of the graphite matrix by calculation (the obtained composite mass - graphite matrix mass) / graphite matrix mass), and the reticulated carbon nanotubes and the reticulated carbon fibers have an average diameter of 100 ～500 nm, average length 5 to 100 μm.

Example 2, a spherical natural graphite having a particle size D ₅₀ of 3 to 40 μm and a carbon content of 85% was placed in a VC-500 mixer, and a 3% catalyst Fe(NO ₃ ) ₃ solid phase was introduced, and the rotation speed was 5000r/min, mixing time is 5min, the mixture is obtained; the mixture is placed in the cavity of the rotary furnace, the volume of the mixture is 50% of the furnace capacity, and the nitrogen gas is introduced at a flow rate of 0.05 m ³ /h to 50 ° C / min. The temperature is raised to 300 ° C, and the furnace chamber is kept for 0.1 h; then the carbon source gas methane is introduced at a flow rate of 0.05 m ³ /h, and the carbon source gas is stopped after 5 h, and maintained at 300 ° C for 6 h; Cool to room temperature; continue to pass nitrogen gas protection at a flow rate of 0.05 m ³ /h, heat up to 3000 ° C at a rate of 50 ° C / min for 0.5 h, use cooling water between the furnace wall and the heat conduction layer in the furnace wall The method of cooling is performed to room temperature, and nitrogen gas is stopped; the moisture content of the obtained composite material is controlled to be less than 0.1%, and then sieved, demagnetized, the number of times of demagnetization is 5 times, the magnetic induction intensity is 10000 Gs, and the treatment temperature is 10 °C, the number of electromagnetic hammer strikes is 20 / sec; lithium ion with an average particle size D ₅₀ of 18.0 μm is obtained. Sub-cell anode material, finished packaging. The specific surface area was 4.6 m ² /g by the BET method. Observed in situ in the form of a PW3040/60 X' Pert X-ray diffractometer from the Dutch PANalytical Instruments, reticulated carbon nanotubes and/or carbon fibers grown on the surface of the graphite substrate, and/or a network mixed between the graphite substrates The carbon nanotubes and/or carbon fibers are composite materials, and the crystal layer spacing d _{002 of the} composite material is between 0.3356 and 0.347 nm. The mass of the reticulated carbon nanotubes and the reticulated carbon fibers was calculated to be 12.4% of the mass of the graphite matrix. The reticulated carbon nanotubes and the reticulated carbon fibers have an average diameter of 100 to 500 nm and an average length of 5 to 100 μm.

In Example 3, artificial graphite having a particle size D ₅₀ of 3 to 40 μm and a carbon content of 85% was placed in a VC-500 mixer, and a 4% catalyst Fe(NO ₃ ) ₃ liquid phase was introduced, and the rotation speed was 500r. /min, mixing time is 180min, the solvent used is water, the mass of the solvent is 0.1 times the mass of the graphite matrix, the mixing temperature is 10 ° C, the gas phase is dried by a spray dryer, the inlet temperature is 150 ° C, and the outlet temperature is 50. °C, pressure is 10Pa, feed flow rate is 1000kg / h, the mixture is obtained; the mixture is placed in the furnace cavity of the rotary furnace, the volume of the mixture is 0.1% of the furnace capacity, and the nitrogen gas is introduced at a flow rate of 5 m ³ /h. The temperature was raised to 600 ° C at a rate of 10 ° C / min, and the furnace cavity was rotated at 10 rpm for 0.2 h; then the carbon source gas acetylene was introduced at a flow rate of 5 m ³ /h, and the carbon source gas was stopped after 3 h, and Hold at 600 ° C for 3 h; naturally cool to room temperature; continue to pass nitrogen at a flow rate of 5 m ³ /h, heat up to 600 ° C at 10 ° C / min for 5 h, naturally cool to room temperature, stop introducing nitrogen; The moisture content of the composite material is controlled to be below 0.1%, and then the sieve is demagnetized. 1 times the number of magnetic, magnetic induction 30000Gs, the treatment temperature is 20 ℃, electromagnetic hammer blow was 100 times / sec; to give an average particle size D ₅₀ of 17.9μm negative electrode material for lithium ion batteries, the finished package. The specific surface area was 3.6 m ² /g by the BET method. Observed in situ by a PW3040/60 X' Pert X-ray diffractometer from the Dutch PANalytical Instruments, reticulated carbon nanotubes and/or carbon fibers coated on the surface of the graphite substrate, and/or mixed between the graphite substrates The composite material is composed of reticulated carbon nanotubes and/or carbon fibers, and the crystal layer spacing d _{002 of the} composite material is between 0.3356 and 0.347 nm. The mass of the reticulated carbon nanotubes and the reticulated carbon fibers measured by calculation was 11.8% of the mass of the graphite matrix. The reticulated carbon nanotubes and the reticulated carbon fibers have an average diameter of 100 to 500 nm and an average length of 5 to 100 μm.

Example 4, carbon microspheres having a particle size D ₅₀ of 3 to 40 μm and a carbon content of 85% were placed in a VC-150 mixer, and 0.05% of the catalyst Fe(NO ₃ ) _{3 was introduced for} solid phase mixing. 2400r/min, mixing time is 90min, the mixture is obtained; the mixture is placed in the furnace cavity of the rotary furnace, the volume of the mixture is 20% of the furnace capacity, and the nitrogen gas is introduced at a flow rate of 2 m ³ /h to 30 ° C / min. The temperature was raised to 1000 ° C, and the furnace cavity was rotated at 15 rpm for 0.3 h; then the carbon source gas acetylene was introduced at a flow rate of 2 m ³ /h, and the carbon source gas was stopped after 2 h, and maintained at 1000 ° C. 1h; using cooling water between the furnace wall and the heat transfer layer in the furnace wall to cool down to room temperature; continuously flowing nitrogen at a flow rate of 2 m ³ /h, and heating to 1000 ° C at a rate of 30 ° C / min 4h, naturally cool to room temperature, stop the introduction of nitrogen; the moisture content of the obtained composite material is controlled below 0.1%, and then sieved, demagnetization, demagnetization times 2 times, magnetic induction intensity is 30000Gs, processing temperature is 20 ℃, electromagnetic hammer blow was 100 times / sec; to give an average particle size D ₅₀ of 22.1μm lithium Subcell negative electrode material, the finished package. The specific surface area was 5.7 m ² /g by the BET method. Observed in situ by a PW3040/60 X' Pert X-ray diffractometer from the Dutch PANalytical Instruments, reticulated carbon nanotubes and/or carbon fibers coated on the surface of the graphite substrate, and/or mixed between the graphite substrates The composite material is composed of reticulated carbon nanotubes and/or carbon fibers, and the crystal layer spacing d _{002 of the} composite material is between 0.3356 and 0.347 nm. The mass of the reticulated carbon nanotubes and the reticulated carbon fibers measured by calculation was 14.7% of the mass of the graphite matrix. The reticulated carbon nanotubes and the reticulated carbon fibers have an average diameter of 100 to 500 nm and an average length of 5 to 100 μm.

In Example 5, conductive graphite having a particle size D ₅₀ of 3 to 40 μm and a carbon content of 85% was placed in a VC-150 mixer, and a 1% catalyst Fe(NO ₃ ) ₃ liquid phase was introduced, and the rotation speed was 8000 r. /min, mixing time is 5min, the solvent used is organic solvent anhydrous ethylene glycol, the mass of the solvent is 3.0 times the mass of the graphite matrix, the mixing temperature is 90 ° C, and the gas is dried by a spray dryer at an inlet temperature of 200 ° C, the outlet temperature is 80 ° C, the pressure is 30 Pa, the feed flow rate is 550 kg / h, the mixture is obtained; the mixture is placed in the furnace cavity of the rotary furnace, the volume of the mixture is 15% of the furnace capacity, 8 m ³ / h The flow rate was passed through nitrogen, and the temperature was raised to 1100 ° C at a rate of 40 ° C / min, and the furnace chamber was rotated at 5 rpm for 0.4 h; then the carbon source gas acetylene was introduced at a flow rate of 8 m ³ /h, and the loading was stopped after 4 h. Carbon source gas, and maintained at 1100 ° C for 5 h; use cooling water between the furnace wall and the furnace wall to cool down to room temperature; continue to flow nitrogen at a flow rate of 8 m ³ / h, Increasing the temperature at 40 ° C / min to 1100 ° C for 8 h, naturally cooling to room temperature, stop the introduction of nitrogen The moisture content of the obtained composite material is controlled to be less than 0.1%, and then sieved, demagnetized, the number of times of demagnetization is 10 times, the magnetic induction intensity is 3000 Gs, the treatment temperature is 10 ° C, and the number of electromagnetic hammer strikes is 180 / sec. A lithium ion battery anode material having an average particle size D ₅₀ of 5.3 μm is packaged in a finished product. Tested by BET method, specific surface area of 15 m ² /g, observed in the PW3040/60 X' Pert X-ray diffractometer of the Dutch PANaly Instruments, reticulated carbon nanotubes grown in situ on the surface of the graphite substrate and / or The carbon fiber, and/or the reticulated carbon nanotubes and/or carbon fibers mixed between the graphite substrates constitute a composite material, and the crystal layer spacing d _{002 of the} composite material is 0.3356 to 0.347 nm. The mass of the reticulated carbon nanotubes and the reticulated carbon fibers was measured by calculation to be 0.1% of the mass of the graphite matrix. The reticulated carbon nanotubes and the reticulated carbon fibers have an average diameter of 100 to 500 nm and an average length of 5 to 100 μm.

Example 6, a spherical natural graphite having a particle size D ₅₀ of 3 to 40 μm and a carbon content of 85% was placed in a VC-150 mixer, and a 0.1% catalyst Fe(NO ₃ ) ₃ liquid phase was introduced, and the rotation speed was 3200r / min, mixing time is 90min, the solvent used is the organic solvent N-methylpyrrolidone NMP, the mass of the solvent is twice the mass of the graphite matrix, the mixing temperature is 35 ° C, the gas phase is dried by a spray dryer, the inlet temperature is 350 ° C, the outlet temperature is 150 ° C, the pressure is 100 Pa, the feed flow rate is 150 kg / h, the mixture is obtained; the mixture is placed in the furnace cavity of the rotary furnace, the volume of the mixture is 20% of the furnace capacity, to 5 m ³ / The flow rate of h was introduced into the nitrogen gas, and the temperature was raised to 800 ° C at a rate of 25 ° C / min, and the furnace chamber was rotated at 15 rpm for 0.25 h; then the carbon source gas acetylene was introduced at a flow rate of 5 m ³ /h for 2.5 h. Stop loading the carbon source gas and keep it at 800 °C for 3h; naturally cool down to room temperature; continue to pass nitrogen at a flow rate of 5m ³ /h, heat up to 800 ° C at 25 ° C / min for 5h, naturally cool down to At room temperature, nitrogen gas is stopped; the moisture content of the obtained composite material is controlled. 0.1% or less, and then sieved, in addition to magnetic, magnetic as 10. In addition, magnetic induction 3000GS, a treatment temperature of 10 ℃, electromagnetic hammer blow was 180 times / sec, an average particle size D ₅₀ of the lithium ion 20.8μm Battery anode material, finished packaging. The specific surface area was 10 m ² /g by the BET method. Observed in situ in the form of a PW3040/60 X' Pert X-ray diffractometer from the Dutch PANalytical Instruments, reticulated carbon nanotubes and/or carbon fibers grown on the surface of the graphite substrate, and/or a network mixed between the graphite substrates The carbon nanotubes and/or carbon fibers are composite materials, and the crystal layer spacing d _{002 of the} composite material is between 0.3356 and 0.347 nm. The mass of the reticulated carbon nanotubes and the reticulated carbon fibers was determined by calculation to be 5.8% of the mass of the graphite matrix. The reticulated carbon nanotubes and the reticulated carbon fibers have an average diameter of 100 to 500 nm and an average length of 5 to 100 μm.

Electrochemical performance test: The lithium ion battery anode material prepared in Examples 1 to 6 and the binder SBR: CMC were mixed and slurried according to a mass ratio of 98:1:1, coated on a copper foil collector, and vacuum dried. After that, it is used as a negative electrode; the 18650 type battery cell is assembled by a conventional production process, the positive electrode material is LiCoO ₂ , LiNiO ₂ or LiMn ₂ O ₄ , the EC/DMC/MEC solution using 1M LiPF6 is used as the electrolyte, and the separator is PE/PP/PE composite. Membrane, testing the first charge-discharge specific capacity of the lithium-ion battery anode material, the first efficiency, and the discharge capacity after the 10th cycle, the rapid charge-discharge performance evaluation is charged with a constant current of 0.5 mA/cm ² , and then 1 C, 5 C, respectively. , 10C discharge current discharge, test changes in discharge capacity. The test equipment is the CT2001C battery detection system of Wuhan Jinnuo's blue battery test system. The test results are listed in Table 1.

Comparative Example 1 Using the prior art spherical natural graphite material, the 18650 type battery cell was prepared according to the above lithium ion battery preparation method, and the electrochemical performance was tested by the same method and equipment. The test results are listed in Table 1;

Comparative example 2 Using the prior art artificial graphite MCMB, the 18650 type battery cell was prepared according to the above lithium ion battery preparation method, and the electrochemical performance was tested by the same method and equipment, and the test results are listed in Table 1;

Table 1 Electrochemical properties measured in Examples 1 to 6 and Comparative Examples 1 and 2

		Example 1	Example 2	Example 3	Example 4	Example 5	Example 6	Comparative example 1	Comparative example 2
First cycle	Charging capacity (mAh/g)	388	370	345	368	384	372	365	373
First cycle	Discharge specific capacity (mAh/g)	365	345	320	345	358	350	331	336
First cycle	Irreversible specific capacity (mAh/g)	twenty three	25	25	twenty three	26	twenty two	34	37
First cycle	Coulomb efficiency (%)	94.1	93.2	92.8	93.8	93.2	94.1	90.7	90.1
10th cycle discharge capacity (mAh/g)		360	342	307	335	354	347	314	335
Rate discharge	1C discharge specific capacity (mAh/g)	357	340	315	342	352	346	329	333
Rate discharge	5C discharge specific capacity (mAh/g)	338	325	296	318	323	315	301	310
Rate discharge	10C discharge specific capacity (mAh/g)	324	315	287	315	317	308	280	300

As can be seen from the comparison, the lithium ion battery anode material prepared by the method of the invention has excellent electrochemical performance as the anode material of the lithium ion battery, and the first discharge specific capacity is increased by 10~30 mAh/g, and the first efficiency is improved by 1 to 5%. After 10 weeks, the reversible capacity retention rate was 98% or more, and the rate performance 10C/1C ratio was increased by 1 to 5%.

Carbon nanotubes are hollow tubular structures. This structure of carbon nanotubes has excellent electrical conductivity and thus has potential applications in many fields. The invention adopts chemical vapor deposition method to prepare carbon nanotubes, and uses a transition metal or an oxide thereof as a growth catalyst to grow carbon atoms in situ on the surface of the substrate to form carbon nanotubes at a certain temperature.

The invention provides a composite anode material by in situ growth of reticulated carbon nanotubes and/or carbon fibers on the surface of a graphite substrate by an electrochemical vapor deposition method, and the lithium ion battery using the composite anode material as a cathode has a high charge and discharge capacity and a rate charge. It has good discharge performance, excellent cycle performance and liquid absorption performance, low production cost, reduced pole piece expansion, simple process and easy industrial reproduction.

Electrochemical performance test: The lithium ion battery anode material prepared in Examples 7 to 13 and the binder SBR: CMC were mixed and slurried according to a mass ratio of 97:2:1 to obtain a mixed slurry having a mass concentration of 10%, and coated. It is vacuum-dried on a 10μm thick copper foil collector and used as a negative electrode. The 18650 type battery cell is assembled by a conventional production process. The positive electrode material is LiCoO ₂ , LiNiO ₂ or LiMn ₂ O ₄ , and the electrolyte is 1 mol/L LiPF ₆ . The EC/DMC/EMC solution has a volume ratio of l:1:1, the separator is a PE/PP/PE composite membrane, and the CT2001C battery detection system of the Wuhan Jinnuo blue battery test system is used to test the lithium ion battery anode material for the first time. The discharge capacity and the first-time efficiency, rapid charge-discharge performance evaluation were performed by a constant current of 0.5 mA/cm ² , and then discharged at discharge currents of 1 C, 10 C, and 20 C, respectively, to test changes in discharge capacity.

In Example 7, the natural graphite containing 85% of carbon was heat-treated, mixed with a 0.05% catalyst Fe(NO ₃ ) ₃ solid phase, and the mixture was vapor-deposited with a carbon source gas methane, and the resultant was sieved and demagnetized. Machine magnetic removal, packaging. The process data and electrical performance test results are shown in Tables 2 and 3, respectively.

3, the lithium ion battery anode material particle size D ₅₀ of 3 ~ 50um, in situ on the surface of graphite substrate grown carbon negative electrode material is disordered carbon nano columnar structure, the spacing more uniform distribution, the average diameter of 1 to 100 nm.

As shown in FIG. 4, the lithium ion battery using the negative electrode material for a lithium ion battery of the present invention has a 20 C discharge specific capacity of 318 mAh/g and a 10 C discharge ratio at different rates at normal temperature (25 ° C). Capacity is 329 mAh/g, 1C discharge capacity is 365 mAh/g, indicating that the ratio performance 20C/1C ratio reached 87%, and the 10C/1C ratio reached 90%. Since the negative electrode material of the lithium ion battery of the present invention has a nano columnar structure grown in situ on the surface of the graphite substrate, a dense coating layer is formed on the surface of the graphite substrate, so that the rate performance is improved.

In Example 8, a natural flake graphite having a carbon content of 85% was heat-treated, mixed with a 5% catalyst Fe(NO ₃ ) ₃ solid phase, and the mixture was vapor-deposited with a carbon source gas acetylene, and the resultant was sieved to remove Magnetic machine demagnetization, packaging. The process data and electrical performance test results are shown in Tables 2 and 3, respectively.

Example 9, heat treatment of 85% carbon microcrystalline graphite, liquid phase mixing with 2% catalyst Fe(NO ₃ ) ₃ , solid-liquid ratio of 5%, gas phase coating of the mixture with carbon source gas methane, The resultant was sieved, demagnetized by a magnetic machine, sieved, and packaged. The process data and electrical performance test results are shown in Tables 2 and 3, respectively.

In Example 10, the natural graphite containing 85% of carbon was heat-treated, mixed with 0.1% of Fe(NO ₃ ) ₃ catalyst, and the solid-liquid ratio was 6%. The mixture was vapor-deposited with the carbon source gas ethylene. The material is sieved, and the magnetic machine is demagnetized and packaged. The process data and electrical performance test results are shown in Tables 2 and 3, respectively.

In Example 11, the artificial graphite containing 85% of carbon was heat-treated, mixed with a 1% catalyst Fe(NO ₃ ) ₃ liquid phase, and the solid-liquid ratio was 7%, and the mixture was vapor-deposited with the carbon source gas methane, and the obtained product was obtained. The material is sieved, and the magnetic machine is demagnetized and packaged. The process data and electrical performance test results are shown in Tables 2 and 3, respectively.

In Example 12, a carbon microsphere having 85% carbon content was heat-treated, mixed with a 2% catalyst Fe(NO ₃ ) ₃ solid phase, and the mixture was vapor-deposited with a carbon source gas CO ₂ , and the resultant was sieved. In addition to magnetic demagnetization, packaging. The process data and electrical performance test results are shown in Tables 2 and 3, respectively.

In Example 13, a conductive graphite containing 85% of carbon was heat-treated, mixed with a solid phase of 3% Fe(NO ₃ ) ₃ , and the mixture was vapor-deposited with a carbon source gas, and the resultant was sieved and demagnetized. Machine magnetic removal, packaging. The process data and electrical performance test results are shown in Tables 2 and 3, respectively.

Comparative Example 3, using a prior art natural graphite material having a carbon content of 85% and a specific resistance of 9 × 10 -6 Ωm, a test battery was fabricated as described above, and its performance was tested. The electrical performance test results are shown in Table 3.

As shown in FIG. 5, the battery 10C made of the lithium ion battery anode material of the present invention has a discharge specific capacity of 329 mAh/g, and under the same manufacturing conditions, a natural graphite anode having a carbon content of 85% in Comparative Example 3 is used. The discharge capacity of the battery 10C made of the material was 316 mAh/g, indicating that the lithium ion battery anode material obtained by the preparation method of the present invention has excellent high rate performance.

Table 2 Process data of Examples 7 to 13

实施例Example	热处理Heat treatment	混合mixing	气相沉积、保温Vapor deposition, insulation	筛分、除磁Screening, demagnetization
77	天然石墨，氮气流量0.5m³/h，升温速度20℃/min，300℃热处理 144h，占炉膛容量的10%；Natural graphite, nitrogen flow rate 0.5m ³ /h, heating rate 20 ° C / min, heat treatment at 300 ° C 144h, accounting for 10% of the furnace capacity;	与0.05%的Fe(NO₃)3，固相混合，转速100 r/min，处理时间200min，处理温度80℃；Mixed with 0.05% Fe(NO ₃ ) 3 , solid phase, rotation speed 100 r / min, treatment time 200 min, treatment temperature 80 ° C;	升温速度0.1℃/min，氮气流量0.1m³/h，炉腔旋转转速5rpm，温度300℃，保持时间0.1h，碳源气体甲烷流量0.1m³/h，保持时间0.1h；停止后300℃保持0.5h，降温至100℃以下；The heating rate is 0.1 °C/min, the nitrogen flow rate is 0.1 m ³ /h, the furnace chamber rotation speed is 5 rpm, the temperature is 300 ° C, the holding time is 0.1 h, the carbon source gas methane flow rate is 0.1 m ³ /h, the holding time is 0.1 h; the stop is 300 ° C. Maintain 0.5h, cool down to below 100 °C;	除磁5次，磁感应强度8000Gs，处理温度25℃，电磁锤打击次数65次/秒。In addition to magnetic 5 times, the magnetic induction intensity is 8000Gs, the processing temperature is 25°C, and the number of electromagnetic hammer strikes is 65 times/second.
88	天然鳞片石墨，氮气流量20m³/h，升温速度1℃/min，3000℃热处理 1h，占炉膛容量的50%；Natural flake graphite, nitrogen flow rate 20m ³ /h, heating rate 1 ° C / min, heat treatment at 3000 ° C for 1 h, accounting for 50% of the furnace capacity;	与5%的Fe(NO₃)3，固相混合，转速3000 r/min，处理时间5min，处理温度20℃；Mixed with 5% Fe(NO ₃ ) 3 , solid phase, rotation speed 3000 r / min, treatment time 5 min, treatment temperature 20 ° C;	升温速度50℃/min，氮气流量10m³/h，炉腔旋转转速20rpm，温度1300℃，保持时间0.5h，碳源气体乙炔流量10m³/h，保持时间0.1h；停止后300℃保持5h，降温至100℃以下；The heating rate is 50 °C/min, the nitrogen flow rate is 10m ³ /h, the furnace chamber rotation speed is 20rpm, the temperature is 1300°C, the holding time is 0.5h, the carbon source gas acetylene flow rate is 10m ³ /h, the holding time is 0.1h; after stopping, it is kept at 300°C for 5h. , cooling down to below 100 ° C;	除磁8次，磁感应强度12000Gs，处理温度40℃，电磁锤打击次数100次/秒。In addition to magnetic 8 times, the magnetic induction intensity is 12000Gs, the processing temperature is 40°C, and the number of electromagnetic hammer strikes is 100 times/second.
99	微晶石墨，氩气流量5m³/h，升温速度5℃/min，600℃热处理 8h，占炉膛容量的1%；Microcrystalline graphite, an argon gas flow rate of 5m ³ / h, heating rate 5 ℃ / min, a heat treatment 600 ℃ 8h, 1% of the capacity of the furnace;	与2%的Fe(NO₃)₃，液相混合，固体质量为固体和液体总质量的10%，转速600 r/min，处理时间180min，处理温度80℃；Mixed with 2% Fe(NO ₃ ) ₃ , liquid phase, solid mass is 10% of total mass of solid and liquid, rotation speed 600 r/min, treatment time 180 min, treatment temperature 80 ° C;	升温速度10℃/min，氩气流量1m³/h，炉腔旋转转速5rpm，温度800℃，保持时间0.2h，碳源气体甲烷流量1m³/h，保持时间0.2h；停止后800℃保持1h，降温至100℃以下；The heating rate is 10°C/min, the argon flow rate is 1m ³ /h, the furnace chamber rotation speed is 5rpm, the temperature is 800°C, the holding time is 0.2h, the carbon source gas methane flow rate is 1m ³ /h, the holding time is 0.2h; the stop is 800°C. 1h, cooling down to below 100 °C;	除磁1次，磁感应强度30000Gs，处理温度80℃，电磁锤打击次数10次/秒。In addition to magnetic one time, the magnetic induction intensity is 30000Gs, the processing temperature is 80°C, and the number of electromagnetic hammer strikes is 10 times/second.
1010	天然石墨，氮气流量10m³/h，升温速度10℃/min，1800℃热处理 6h，占炉膛容量的20%；Natural graphite, nitrogen flow rate 10m ³ /h, heating rate 10 ° C / min, heat treatment at 1800 ° C for 6 h, accounting for 20% of the furnace capacity;	与0.1%的Fe(NO₃)₃，液相混合，固体质量为固体和液体总质量的70%，转速1300 r/min，处理时间90min，处理温度30℃；Mixed with 0.1% Fe(NO ₃ ) ₃ , liquid phase, the solid mass is 70% of the total mass of solid and liquid, the rotation speed is 1300 r/min, the treatment time is 90 min, and the treatment temperature is 30 ° C;	升温速度15℃/min，氮气流量5m³/h，炉腔旋转转速15rpm，温度1000℃，保持时间0.4h，碳源气体乙烯流量5m³/h，保持时间2h；停止后1000℃保持2h，降温至100℃以下；The heating rate is 15 °C/min, the nitrogen flow rate is 5m ³ /h, the furnace chamber rotation speed is 15rpm, the temperature is 1000°C, the holding time is 0.4h, the carbon source gas ethylene flow rate is 5m ³ /h, the holding time is 2h; after stopping, 1000°C is kept for 2h, Cool down to below 100 ° C;	除磁2次，磁感应强度20000Gs，处理温度60℃，电磁锤打击次数30次/秒。In addition to magnetic 2 times, the magnetic induction intensity is 20000Gs, the processing temperature is 60 °C, and the number of electromagnetic hammer strikes is 30 times/second.
1111	人造石墨，氩气流量8m³/h，升温速度20℃/min，2400℃热处理 38h，占炉膛容量的15%；Artificial graphite, argon flow rate 8m ³ /h, heating rate 20 ° C / min, 2400 ° C heat treatment 38h, accounting for 15% of furnace capacity;	与1%的Fe(NO₃)₃，液相混合，固体质量为固体和液体总质量的60%，转速3000 r/min，处理时间120min，处理温度60℃；Mixed with 1% Fe(NO ₃ ) ₃ , liquid phase, solid mass is 60% of total mass of solid and liquid, rotation speed 3000 r/min, treatment time 120 min, treatment temperature 60 ° C;	升温速度20℃/min，氩气流量0.5m³/h，炉腔旋转转速8rpm，温度600℃，保持时间0.3h，碳源气体甲烷流量0.5m³/h，保持时间4h；停止后600℃保持6h，降温至100℃以下；Heating rate 20 ° C / min, argon flow 0.5 m ³ / h, furnace rotation speed 8 rpm, temperature 600 ° C, holding time 0.3 h, carbon source gas methane flow 0.5 m ³ / h, holding time 4 h; Maintain 6h, cool down to below 100 °C;	除磁5次，磁感应强度18000Gs，处理温度10℃，电磁锤打击次数180次/秒。In addition to magnetic 5 times, the magnetic induction intensity is 18000Gs, the processing temperature is 10 °C, and the number of electromagnetic hammer strikes is 180 times/second.
1212	碳微球，氮气流量15m³/h，升温速度3℃/min，1500℃热处理 2h，占炉膛容量的40%；Carbon microspheres, nitrogen flow rate 15m ³ /h, heating rate 3 ° C / min, heat treatment at 1500 ° C 2h, accounting for 40% of furnace capacity;	与2%的Fe(NO₃)₃，固相混合，转速2000 r/min，处理时间10min，处理温度40℃；Mixed with 2% Fe(NO ₃ ) ₃ , solid phase, rotation speed 2000 r/min, treatment time 10 min, treatment temperature 40 ° C;	升温速度30℃/min，氮气流量8m³/h，炉腔旋转转速15rpm，温度700℃，保持时间0.2h，碳源气体CO₂流量8m³/h，保持时间2h；停止后700℃保持5h，降温至100℃以下；The heating rate is 30 °C/min, the nitrogen flow rate is 8m ³ /h, the furnace chamber rotation speed is 15rpm, the temperature is 700°C, the holding time is 0.2h, the carbon source gas CO ₂ flow rate is 8m ³ /h, the holding time is 2h; after stopping, the 700°C is kept for 5h. , cooling down to below 100 ° C;	除磁10次，磁感应强度3000Gs，处理温度35℃，电磁锤打击次数3次/秒。In addition to magnetic 10 times, the magnetic induction intensity is 3000Gs, the processing temperature is 35°C, and the number of electromagnetic hammer strikes is 3 times/second.
1313	导电石墨，氮气流量6m³/h，升温速度15℃/min，2800℃热处理 3h，占炉膛容量的35%；Conductive graphite, nitrogen flow rate 6m ³ /h, heating rate 15 ° C / min, 2800 ° C heat treatment 3h, accounting for 35% of the furnace capacity;	与3%的Fe(NO₃)₃，固相混合，转速2400 r/min，处理时间5min，处理温度20℃；Mixed with 3% Fe(NO ₃ ) ₃ , solid phase, rotation speed 2400 r/min, treatment time 5 min, treatment temperature 20 ° C;	升温速度40℃/min，氮气流量10m³/h，炉腔旋转转速15rpm，温度1300℃，保持时间0.1h，碳源气体乙烯流量10m³/h，保持时间1h；停止后1300℃保持3h，降温至100℃以下；The heating rate is 40 ° C / min, the nitrogen flow rate is 10 m ³ /h, the furnace chamber rotation speed is 15 rpm, the temperature is 1300 ° C, the holding time is 0.1 h, the carbon source gas ethylene flow rate is 10 m ³ /h, the holding time is 1 h, and the 1300 ° C is kept for 3 h after stopping. Cool down to below 100 ° C;	除磁9次，磁感应强度28000Gs，处理温度70℃，电磁锤打击次数150次/秒。9 times of magnetic removal, magnetic induction intensity of 28000Gs, processing temperature of 70 ° C, electromagnetic hammer hits of 150 times / sec.

Table 3 Electrical property test results of Examples 7 to 13 and Comparative Example 3

		Example 7	Example 8	Example 9	Example 10	Example 11	Example 12	Example 13	Comparative example 3
Resistivity (Ωm)		4.6×10 ^-6	7.8×10 ^-6	6.4×10 ^-6	5.8×10 ^-6	5.3×10 ^-6	7.3×10 ^-6	4.8×10 ^-6	9.0×10 ^-6
First cycle	Reversible capacity (mAh/g)	370	338	354	360	365	350	369	356
First cycle	effectiveness(%)	95	93	94	94	93	93	94	91
Cyclical (100%)		94.8	95.1	94.4	95.2	94.0	93.6	93.0	90.0
Rate discharge	1C discharge capacity (mAh/g)	365	332	352	357	360	350	363	351
Rate discharge	10C discharge capacity (mAh/g)	329	279	309	318	338	312	330	316
Rate discharge	20C discharge capacity (mAh/g)	318	288	300	308	324	322	320	306

It can be seen from the test results that the lithium-ion battery anode material prepared by the method of the invention has the first reversible capacity, the first coulombic efficiency, the cycle performance and the rate performance of the lithium ion battery fabricated by using the material, indicating the surface of the graphite substrate. A lithium ion battery anode material having nano-columnar and/or nano-particle structure grown in situ forms a dense coating layer on the surface of the graphite substrate to improve its electrochemical performance; meanwhile, the lithium ion battery anode prepared by the method of the invention The resistivity of the material is smaller than that before the coating, indicating that the method of the present invention makes the contact between the electrode material particles and the current collector after the charge and discharge cycle, and solves the problem between the electrode material, the conductive agent carbon black and the current collector. The problem that the conductive network is broken and the resistance is increased, thereby improving the cycle performance of the battery.

Claims

A negative electrode material for a lithium ion battery, characterized in that: the anode material of the lithium ion battery is composed of a graphite matrix, reticulated carbon nanotubes and/or carbon fibers grown in situ on the surface of the graphite substrate, and/or mixed in a graphite matrix The composite carbon nanotubes and/or carbon fibers constitute a composite material, and the crystal layer spacing d 002 of the composite material is between 0.3356 and 0.347 nm, and the specific surface area is between 1 and 20 m 2 /g; the reticulated carbon nanotubes and the mesh The mass of the carbon fiber is 0.1 to 15% by mass of the graphite matrix; and the reticulated carbon fiber and the reticulated carbon fiber have an average diameter of 100 to 500 nm and an average length of 5 to 100 μm.
A method for preparing a negative electrode material for a lithium ion battery comprises the following steps: 1. adding a catalyst having a mass of graphite matrix of more than 0 to 5% in a graphite matrix material to obtain a mixture; the graphite matrix has a carbon content of 85 More than one of natural flake graphite, microcrystalline graphite, artificial graphite, carbon microspheres, and conductive graphite, one or more of a spherical shape, a block shape, and a sheet shape having a spherical shape and a length-to-minor axis ratio of 1.0 to 4.5. The particle size D 50 is 3-40 μm; the catalyst is: a nitrate, a sulfate, a halide or an oxide of iron, cobalt or nickel; 2. The mixture is placed in a furnace chamber at a rate of 0.1 to 50 ° C/min. When the temperature is raised, the protective gas nitrogen or argon gas is introduced at a flow rate of 0.05 to 10 m 3 /h. When the temperature reaches 300 to 1300 ° C, the carbon source gas is introduced at a flow rate of 0.05 to 10 m 3 /h, and the passage time is 0.1～5h; the carbon source gas is methane, acetylene, ethylene, CO 2 , natural gas, liquefied petroleum gas, benzene or thiophene; 3. cooling water is introduced between the furnace wall and the heat conducting layer in the furnace wall to cool Way or natural cooling method in the furnace to 100 The following four; at a heating rate of 0.5 ~ 50 ° C / min, the temperature is raised to 300 ~ 3000 ° C, heat preservation 0.5 ~ 10h; 5, using the cooling water between the furnace wall and the furnace wall to cool the way Or the natural cooling mode in the furnace is below 100 °C, and the protective gas nitrogen or argon gas is stopped to obtain the negative electrode material of the lithium ion battery.
The method for preparing a negative electrode material for a lithium ion battery according to claim 2, wherein the catalyst is mixed by solid phase mixing, mechanically mixed by a high speed modified mixer, a conical mixer or a ball mill, and is 500 to 5000r. /min speed, mix 5 ~ 180min.
The method for preparing a negative electrode material for a lithium ion battery according to claim 2, wherein the catalyst is mixed in a liquid phase, mixed by a high speed mixer or a sol gel, and mixed at a speed of 500 to 8000 rpm. ~180min, the solvent used is water or organic solvent, the organic solvent is anhydrous ethylene glycol, glycerol, isopropanol or acetone, tetrahydrofuran, N-methylpyrrolidone NMP or dimethylacetamide, the quality of the solvent is graphite The substrate is 0.1 to 3.0 times the mass, the mixing temperature is 10 to 90 ° C, and drying is carried out using a spray dryer, a suction filter or a freeze dryer.
The method for preparing a negative electrode material for a lithium ion battery according to claim 4, wherein the spray drying inlet temperature is 150 to 350 ° C, the outlet temperature is 50 to 150 ° C, and the pressure is 10 to 100 Pa.
The method for preparing a negative electrode material for a lithium ion battery according to claim 2, wherein the mixture is placed in a furnace chamber of a rotary furnace, a tube furnace or a carbon tube furnace, and the volume of the mixture is 0.1 to 50% of the furnace capacity. Rotate the furnace chamber at a speed greater than 0 to 20 rpm.
The method for preparing a negative electrode material for a lithium ion battery according to claim 2, wherein the mixture is placed in a furnace chamber of a rotary furnace, a tube furnace or a carbon tube furnace at a rate of 0.1 to 50 ° C/min. When the temperature is raised to 300 to 1300 ° C, the carbon source gas is introduced at a flow rate of 0.05 to 10 m 3 /h after the temperature is maintained for more than 0 to 0.5 h.
The method for preparing a negative electrode material for a lithium ion battery according to claim 2, wherein after the carbon source gas is stopped, the temperature is maintained at 300 to 1300 ° C for more than 0 to 6 h.
The method for preparing a negative electrode material for a lithium ion battery according to any one of claims 2 to 2, wherein the negative electrode material of the lithium ion battery is heated at 100 ° C or lower, vacuum dried or other prior art to control the moisture of the negative electrode material. The content is below 0.1%, sieved, demagnetized, the number of times of demagnetization is 1-10 times, the magnetic induction intensity is 3000 to 30000 Gs, the treatment temperature is 10 to 80 ° C, and the number of electromagnetic hammer strikes is 3 to 180 / sec. A lithium ion battery negative electrode material having a particle size D 50 of 3 to 50 μm.
A negative electrode material for a lithium ion battery, characterized in that: the anode material of the lithium ion battery is composed of a graphite matrix and a nano columnar and/or nanoparticle structure in which the surface is grown in situ; the graphite matrix has a carbon content of 85 More than % of natural graphite, natural flake graphite, microcrystalline graphite, artificial graphite, carbon microspheres or conductive graphite, having spherical, block-like and/or sheet-like topographical features with a spherical, long-axis-to-axis ratio of 1.0 to 4.5, The particle size is D 50 of 3 to 40 um; the nano-columnar and/or nano-granular structure is a disordered crystal, and the nano-columnar and/or nano-granular mass is 0.05 to 10% of the mass of the graphite matrix.
A method for preparing a negative electrode material for a lithium ion battery comprises the following steps: 1. heat treatment, heat treating the graphite substrate at a heating rate of 1 to 20 ° C / min to a temperature of 300 to 3000 ° C in a protective gas nitrogen or argon atmosphere 1～144 h, then the furnace naturally cools to 20 ° C; the graphite matrix material is more than 85% carbon natural graphite, natural flake graphite, microcrystalline graphite, artificial graphite, carbon microspheres or conductive graphite, the particle size is D 50 is 3-40 um; second, mixing, adding a catalyst having a mass of graphite matrix of more than 0 to 5% in the graphite matrix, using solid phase mixing or liquid phase mixing to obtain a mixture; the catalyst is: iron, cobalt Or nickel nitrate, sulfate, halide or oxide; third, vapor deposition, the mixture is placed in the furnace chamber, heated at a rate of 0.1 ~ 50 ° C / min, with a flow rate of 0.1 ~ 10m 3 / h The protective gas nitrogen or argon gas is kept at a temperature of 0.1 to 0.5 h when the temperature reaches 300 to 1300 ° C, and the carbon source gas is introduced at a flow rate of 0.1 to 10 m 3 /h, and the introduction time is 0.1 to 4 h; gas is methane, acetylene, ethylene, CO 2, days Gas, liquefied petroleum gas, benzene or thiophene; Fourth, heat preservation, maintained at 300 ~ 1300 ° C for 0.5 ~ 6h; five, cooling, using compressed air between the furnace wall and the furnace wall to reduce the temperature The method or the natural cooling method in the furnace is below 100 ° C, and the protective gas nitrogen or argon gas is stopped to obtain a negative electrode material of the lithium ion battery.
The method for preparing a negative electrode material for a lithium ion battery according to claim 11, wherein the protective gas has a nitrogen or argon atmosphere and a gas flow rate of 0.5 to 20 m 3 /h.
The method for preparing a negative electrode material for a lithium ion battery according to claim 11, wherein in the heat treatment, the volume of the graphite matrix accounts for 1 to 50% of the capacity of the furnace.
The method for preparing a negative electrode material for a lithium ion battery according to claim 11, wherein a catalyst having a mass of graphite matrix of more than 0 to 5% is added to the graphite matrix, and the solid phase mixing method is used, and the rotation speed is 100. ~3000 r/min, the treatment time is 5 to 200 min, and the treatment temperature is 20 to 80 °C.
The method for preparing a negative electrode material for a lithium ion battery according to claim 11, wherein a catalyst having a mass of graphite matrix greater than 0 to 5% is added to the graphite matrix, and the liquid phase is mixed, and the rotation speed is 600. ~ 3000r / min, mixing time is 90 ~ 180min, mixing temperature is 10 ~ 80 ° C, liquid phase mixing, using a spray dryer, suction filter or freeze dryer to dry, control material moisture content below 2%.
The method for preparing a negative electrode material for a lithium ion battery according to claim 11, wherein the vapor deposition is performed, and the mixture is placed in a furnace of a rotary furnace, a tube furnace or a carbon tube furnace, and is rotated at a speed of 0 to 20 rpm. Furnace cavity.
The method for preparing a negative electrode material for a lithium ion battery according to claim 11, wherein the lithium ion battery negative electrode material is heated to a temperature below 100 ° C and vacuum dried to control the moisture content to be less than 0.1%, and then sieved. In addition to magnetic, the magnetic removal is 1 to 10 times, the magnetic induction intensity is 3000 to 30000 Gs, the processing temperature is 10 to 80 ° C, the number of electromagnetic hammer strikes is 3 to 180 / sec, and the particle size is D 50 is 3 to 50 um.
The method for preparing a negative electrode material for a lithium ion battery according to any one of claims 1 to 3, wherein the heat treatment is performed by heat-treating the graphite substrate at a temperature rising rate of 1 to 20 ° C / min to 300 to 3000 ° C. 144h.
The method for preparing a negative electrode material for a lithium ion battery according to claim 18, wherein the vapor phase deposition comprises placing the mixture in a furnace of a rotary furnace, a tube furnace or a carbon tube furnace at a temperature of 0.1 to 50 ° C/min. The temperature is increased, and a protective gas such as nitrogen or argon is introduced at a flow rate of 0.1 to 10 m 3 /h. When the temperature reaches 300 to 1300 ° C, the temperature is maintained at 0.1 to 0.5 h, and the carbon is introduced at a flow rate of 0.1 to 10 m 3 /h. Source gas, the access time is 0.1 ~ 4h.
A lithium ion battery comprising a negative electrode material, characterized in that the negative electrode material is composed of a graphite matrix, reticulated carbon nanotubes and/or carbon fibers grown in situ on the surface of the graphite substrate, and/or mixed between the graphite substrates. The composite material is composed of reticulated carbon nanotubes and/or carbon fibers, nano-columnars and/or nano-granular structures, and the crystal layer spacing d 002 of the composite material is between 0.3356 and 0.347 nm, and the specific surface area is between 1 and 20 m 2 /g; The mass of the reticulated carbon nanotubes and the reticulated carbon fibers is 0.1 to 15% of the mass of the graphite matrix; the reticulated carbon nanotubes and the reticulated carbon fibers have an average diameter of 100 to 500 nm and an average length of 5 to 100 μm; The anode material is composed of a graphite matrix and a nano-columnar and/or nano-granular structure in which the surface is grown in situ; the graphite matrix is natural graphite having a carbon content of 85% or more, natural flake graphite, microcrystalline graphite, artificial graphite, Carbon microspheres or conductive graphite having a spherical, spheroidal, massive and/or sheet-like topographical shape with a spherical, long-and short-axis ratio of 1.0 to 4.5, a particle size D 50 of 3 to 40 μm; the nano-columnar and/or nano-nano Particle structure For disordered crystals, the nano-columnar and/or nano-granular structure has a mass of 0.05 to 10% of the mass of the graphite matrix.