CN114074940A - Method for coating modified negative electrode material by adopting solid asphalt liquid-phase high-temperature spraying - Google Patents

Method for coating modified negative electrode material by adopting solid asphalt liquid-phase high-temperature spraying Download PDF

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CN114074940A
CN114074940A CN202010809450.0A CN202010809450A CN114074940A CN 114074940 A CN114074940 A CN 114074940A CN 202010809450 A CN202010809450 A CN 202010809450A CN 114074940 A CN114074940 A CN 114074940A
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边浩苹
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Wuxi Taixian Powder Technology Co ltd
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Abstract

A method for coating a modified negative electrode material by adopting solid asphalt liquid phase high-temperature spraying is disclosed, wherein the negative electrode material is prepared from 800-1200 parts of graphite fine powder or silicon monoxide fine powder and 10-50 parts of liquid asphalt. Fluidizing graphite fine powder at a high speed in a high-speed mixer, controlling the temperature within the range of 50-300 ℃, then melting solid asphalt at the temperature of 80-300 ℃, spraying at a high temperature, coating the graphite fine powder or the silicon monoxide fine powder on the surface to obtain a precursor, carrying out high-temperature heat treatment in a tube furnace under the protection of inert gas, preserving the heat, and cooling to room temperature to obtain the liquid-phase high-temperature spray-coated modified negative electrode material. The modified cathode material has excellent electrochemical performance, the first charge-discharge efficiency is up to more than 96%, the rate capability is good, the capacity is high, and the modified cathode material can be applied to high-rate power batteries of electric automobiles, model airplanes, electric tools and the like.

Description

Method for coating modified negative electrode material by adopting solid asphalt liquid-phase high-temperature spraying
Technical Field
The invention relates to the field of materials and electrochemistry, in particular to a method for coating negative electrode materials such as modified graphite and the like by solid asphalt liquid phase high-temperature spraying.
Background
The development of portable electronic devices has advanced dramatically in recent years. In addition, lithium ion secondary batteries are also being gradually pushed into the traffic field. Thus, the demand for lithium ion secondary batteries is continuously increasing, and due to this higher demand, the limitation of graphite negative electrode materials in terms of capacity and power characteristics is becoming more and more significant. In this context, studies on modification of graphite anode materials have been focused. The existing preparation method adopts a solvent to dissolve a wrapping agent which is solid in a normal state into liquid, and the solvent is usually unnecessary impurities and is used as an auxiliary wrapping agent to bring certain influence on the purity of the material.
Disclosure of Invention
The invention aims to provide a preparation method of a graphite cathode material coated and modified by solid asphalt liquid-phase high-temperature spraying, and the prepared material has excellent electrochemical performance, the first charge-discharge efficiency is up to more than 96%, the rate capability is good, and the capacity is high.
The purpose of the invention can be realized by the following steps that the preparation method of the graphite negative electrode material coated and modified by adopting the solid asphalt liquid-phase high-temperature spraying comprises the following steps:
s1, obtaining high-temperature liquid phase asphalt by the solid asphalt with high softening point at the temperature of 80-300 ℃; filtering the high-temperature liquid-phase asphalt, wherein the mesh number of a filter screen is 100-200 meshes;
s2, mixing 800-1200 parts of graphite fine powder or silicon fine powder and 10-50 parts of liquid asphalt in parts by weight; firstly, putting graphite fine powder or silicon fine powder or silica fine powder into a high-speed mixer for high-speed fluidization, keeping the temperature of 50-300 ℃, and then spraying high-temperature liquid-phase asphalt into the high-speed mixer at high temperature to coat the graphite fine powder or the silicon fine powder or the silica fine powder;
s3, feeding the coated material into a coating machine, shaping the coated material, and enabling the asphalt to be more uniform and complete in coating on the surface of the graphite fine powder, the silicon fine powder or the silicon monoxide fine powder;
and S4, carrying out high-temperature heat treatment on the shaped coating material under the protection of inert gas in a tube furnace at the heating rate of 2-8 ℃/min, preserving the heat for 3-10 h, and cooling to room temperature to obtain the liquid-phase coating modified negative electrode material.
Further, the graphite fine powder or the silicon monoxide fine powder is fluidized at a high speed in a high-speed mixer, the stirring linear speed is 10-42 m/s, and the stirring time is 5-20 minutes; and keeping the temperature at 50-300 ℃; the spraying speed of the asphalt is 20-50 s per kilogram of asphalt, the spraying pressure is 0.05-0.3 Mpa, the viscosity of the asphalt is 1000-10000 cps, and the temperature is 80-250 ℃; during spraying, stirring is carried out while spraying, the stirring linear speed is 10-42 m/s, and the time is 5-20 minutes.
Further, the stirring linear speed of the wrapping machine is 10-42 m/s, and the time is 5-20 minutes.
Further, the temperature of the wrapping machine is 100-300 ℃.
Further, the high temperature heat treatment in step S4 is a carbonization treatment at 1000 to 2000 ℃ or a graphitization treatment at 2000 to 3200 ℃.
Further, the inert gas in step S4 is nitrogen gas having a purity of 99% or more.
Furthermore, the particle size of the graphite fine powder, the silicon fine powder or the silicon oxide fine powder is 12.2-20.2 um.
Further, the graphite fine powder is one or more of spherical natural graphite, spheroidal natural graphite, crystalline flake graphite, artificial graphite, petroleum coke, pitch coke and mesocarbon microbeads.
The invention adopts a heating melting mode, has no solvent, does not increase extra impurities and ensures the purity of the material. The modified graphite cathode material produced by the method has excellent electrochemical performance, the first charge-discharge efficiency is up to more than 96%, the rate performance is good, the capacity is high, and the modified graphite cathode material can be applied to high-rate power batteries of electric automobiles, aeromodelling, electric tools and the like.
Drawings
FIG. 1 is a graph of rate discharge curves for a preferred embodiment of the present invention;
FIG. 2 is an SEM image of a preferred embodiment of the invention.
Detailed Description
The present invention will be further described with reference to the following examples.
A preparation method of a liquid-phase high-temperature spray-coated modified graphite negative electrode material comprises the following steps:
s1, obtaining high-temperature liquid phase asphalt by the solid asphalt with high softening point at the temperature of 80-300 ℃; and filtering the high-temperature liquid-phase asphalt, wherein the mesh number of the filter screen is 100-200 meshes.
The cost of high softening point asphalt is lower than that of low softening point asphalt, and the coking value of high softening point asphalt is large. One of the purposes of the coating is to form a layer of amorphous carbon on the surface of the graphite particles, so that the larger the coking value, the better.
S2, mixing 800-1200 parts of graphite fine powder or silicon fine powder and 10-50 parts of liquid asphalt in parts by weight; firstly, putting graphite fine powder or silicon fine powder or silica fine powder into a high-speed mixer for high-speed fluidization, keeping the temperature of 50-300 ℃, and then spraying high-temperature liquid-phase asphalt into the high-speed mixer at high temperature to coat the graphite fine powder or the silicon fine powder or the silica fine powder.
Fluidizing graphite fine powder or silicon fine powder or silica fine powder at high speed in a high-speed mixer, wherein the stirring speed is 10-42 m/s, and the stirring time is 5-20 minutes; and keeping the temperature at 50-300 ℃; the spraying speed of the asphalt is 20-50 s per kilogram of asphalt, the spraying pressure is 0.05-0.3 Mpa, the viscosity of the asphalt is 1000-10000 cps, and the temperature is 80-250 ℃; during spraying, stirring is carried out while spraying, the stirring linear speed is 10-42 m/s, and the time is 5-20 minutes.
The temperature of the high-speed mixer is 50-300 ℃, and the temperature is correspondingly adjusted along with the softening point temperature of the solid asphalt with high softening point.
The particle size of the graphite fine powder or the silicon oxide fine powder is 12.2-20.2 um.
The graphite fine powder is one or more of spherical natural graphite, crystalline flake graphite, artificial graphite, petroleum coke, pitch coke and intermediate-phase carbon microspheres, and the particle size of the graphite fine powder is 12.2-20.2 um. The graphite fine powder adopted in the embodiment is spherical natural graphite, and is a graphite negative electrode material for producing a lithium battery. The main components are as follows: carbon and hydrogen with content more than 99.97%, carbon-hydrogen ratio 25:1, trace elements Fe <20ppm, Na <5ppm, Cr <5ppm, Cu <5ppm, Ni <5ppm, Al <5ppm, Mo <5 ppm.
And S3, feeding the coated material into a coating machine, shaping the coated material, and enabling the asphalt to be more uniform and complete in coating on the surface of the graphite fine powder or the silicon monoxide fine powder.
The stirring linear speed of the wrapping machine is 10-42 m/s, and the time is 5-20 minutes. The temperature of the wrapping machine is 100-300 ℃, and is adjusted correspondingly according to the softening point temperature of the used asphalt, which is slightly higher than the softening point temperature of the used asphalt.
And S4, carrying out high-temperature heat treatment on the shaped coating material under the protection of inert gas in a tube furnace at the heating rate of 2-8 ℃/min, preserving the heat for 3-10 h, and cooling to room temperature to obtain the liquid-phase coating modified negative electrode material.
The high-temperature heat treatment in the step is carbonization treatment at 1000-2000 ℃ or graphitization treatment at 2000-3200 ℃. The inert gas in the step is nitrogen with the purity of more than 99 percent.
The primary effect of the coated graphite powder or silicon powder or silica powder is checked through the loose packing density, the flowability of the powder, the change of the granularity and the change of the tap density, and then the coating condition of the surface is checked by using a microscope, as shown in figure 2; and then, directly manufacturing a finished product to verify the actual effect.
The high-speed mixer, the wrapping machine and the tube furnace are all commercially available equipment.
Preparing a liquid-phase coating modified negative electrode material:
example 1
(1) And (3) carrying out high-temperature treatment on the solid asphalt at the high temperature of 80 ℃ to obtain high-temperature liquid asphalt. And filtering the high-temperature liquid-phase asphalt, wherein the mesh number of the filter screen is 100 meshes.
(2) Spraying 10 parts of high-temperature liquid asphalt at high temperature into a high-speed mixer to coat 1000 parts of graphite fine powder with the particle size of 12.2um, carrying out heat preservation and heating in the high-speed mixer to mix at high speed, wherein the stirring speed of the high-speed mixer is about 42m/s, and stirring for 8 minutes after adding the graphite fine powder. High-temperature liquid-phase pitch high-temperature spraying is carried out after the graphite fine powder is fluidized at a high speed. The spraying speed of the high-temperature liquid phase asphalt is 50s per kilogram of the high-temperature liquid phase asphalt, the spraying pressure is 0.3Mpa, the viscosity of the asphalt is 10000cps, and the temperature is 80 ℃; during spraying, stirring while spraying, wherein the stirring linear speed is 42m/s, and the stirring time is 20 minutes; the temperature of the high speed mixer was about 50 ℃.
(3) And (4) feeding the coated and formed coating material into a coating machine, and shaping the coating material to ensure that the asphalt is more uniform on the graphite surface and completely coated.
The stirring linear speed of the wrapping machine is 10m/s, and the time is 10 minutes. The temperature of the wrapping machine was 100 ℃.
(4) And heating the shaped coating material to 2000 ℃ at the speed of 2 ℃/min under the protection of nitrogen in a tubular furnace, preserving the heat for 3h for graphitization treatment, and cooling to room temperature to obtain the liquid-phase coating modified graphite cathode material.
Example 2
(1) And (3) carrying out high-temperature treatment on the solid asphalt at 200 ℃ to obtain high-temperature liquid asphalt. And filtering the high-temperature liquid-phase asphalt, wherein the mesh number of the filter screen is 110 meshes.
(2) Spraying 20 parts of high-temperature liquid asphalt into a high-speed mixer at high temperature to coat 800 parts of graphite fine powder with the particle size of 16.8um, and carrying out heat preservation, heating and high-speed mixing in the high-speed mixer, wherein the stirring linear speed of the high-speed mixer is 41m/s, the temperature of the high-speed mixer is about 180 ℃, and the temperature of the asphalt is about 200 ℃;
the graphite fine powder is added and then stirred for 5 minutes. High-temperature liquid-phase pitch high-temperature spraying is carried out after the graphite fine powder is fluidized at a high speed. The spraying speed of the asphalt is 30s per kilogram of asphalt, the spraying pressure is 0.2Mpa, the viscosity of the asphalt is 9000cps, and the temperature is 200 ℃; during spraying, stirring was carried out while spraying at a stirring line speed of 41m/s for 12 minutes.
(3) The coated materials enter a coating machine, and the coated materials are shaped, so that the asphalt is more uniform on the surface of the graphite and is completely coated; the stirring linear speed of the wrapping machine was 41m/s and the time was 12 minutes. The temperature of the wrapping machine was 185 ℃.
(4) And heating the shaped coating material to 2200 ℃ at the speed of 3 ℃/min under the protection of nitrogen in a tubular furnace, preserving the heat for 4h for graphitization treatment, and cooling to room temperature to obtain the liquid-phase coating modified graphite cathode material.
Example 3
(1) And (3) carrying out high-temperature 300 ℃ on the solid asphalt to obtain high-temperature liquid asphalt. And filtering the high-temperature liquid-phase asphalt, wherein the mesh number of the filter screen is 200 meshes.
(2) Spraying 30 parts of high-temperature liquid asphalt into a high-speed mixer at high temperature to coat 1100 parts of graphite fine powder with the particle size of 17.5um, and carrying out heat preservation, heating and high-speed mixing in the high-speed mixer, wherein the stirring linear speed of the high-speed mixer is 10m/s, the temperature of the high-speed mixer is about 300 ℃, and the temperature of the asphalt is about 300 ℃;
the graphite fine powder was added and stirred for 20 minutes. High-temperature liquid-phase pitch high-temperature spraying is carried out after the graphite fine powder is fluidized at a high speed. The spraying speed of the asphalt is 20s per kilogram of asphalt, the spraying pressure is 0.05Mpa, the viscosity of the asphalt is 1000cps, and the temperature is 300 ℃; during spraying, the mixture was stirred while being sprayed at a linear velocity of 10m/s for 20 minutes.
(3) The coated materials enter a coating machine, and the coated materials are shaped, so that the asphalt is more uniform on the surface of the graphite and is completely coated; the stirring linear speed of the wrapping machine is 10m/s, and the time is 20 minutes. The temperature of the wrapping machine was 300 ℃.
(4) And heating the shaped coating material to 2400 ℃ at a speed of 4 ℃/min under the protection of nitrogen in a tubular furnace, preserving the heat for 5h for graphitization treatment, and cooling to room temperature to obtain the liquid-phase coating modified graphite cathode material.
Example 4
(1) And (3) subjecting the solid asphalt to 280 ℃ at high temperature to obtain high-temperature liquid asphalt. And filtering the high-temperature liquid-phase asphalt, wherein the mesh number of the filter screen is 180 meshes.
(2) Spraying 40 parts of high-temperature liquid asphalt at high temperature into a high-speed mixer to coat 1150 parts of graphite fine powder with the particle size of 20.2um, and carrying out heat preservation, heating and high-speed mixing in the high-speed mixer, wherein the stirring linear speed of the high-speed mixer is 15m/s, the temperature of the high-speed mixer is about 250 ℃, and the temperature of the asphalt is about 280 ℃;
the graphite fine powder was added and stirred for 15 minutes. High-temperature liquid-phase pitch high-temperature spraying is carried out after the graphite fine powder is fluidized at a high speed. The spraying speed of the asphalt is 25s per kilogram of asphalt, the spraying pressure is 0.08Mpa, the viscosity of the asphalt is 3000cps, and the temperature is 280 ℃; during spraying, the mixture is stirred while being sprayed, the stirring linear speed is 15m/s, and the time is 15 minutes.
(3) The coated materials enter a coating machine, and the coated materials are shaped, so that the asphalt is more uniform on the surface of the graphite and is completely coated; the stirring linear speed of the wrapping machine is 16m/s, and the time is 15 minutes. The temperature of the wrapping machine was 270 ℃.
(4) And heating the shaped coating material to 2600 ℃ at the speed of 5 ℃/min under the protection of nitrogen in a tubular furnace, preserving the heat for 6h for graphitization treatment, and cooling to room temperature to obtain the liquid-phase coating modified graphite cathode material.
Example 5
(1) And (3) subjecting the solid asphalt to high temperature of 250 ℃ to obtain high-temperature liquid asphalt. And filtering the high-temperature liquid-phase asphalt, wherein the mesh number of the filter screen is 170 meshes.
(2) Spraying 50 parts of high-temperature liquid asphalt into a high-speed mixer at high temperature to coat 1200 parts of graphite fine powder with the particle size of 17.1um, and carrying out heat preservation, heating and high-speed mixing in the high-speed mixer, wherein the stirring linear speed of the high-speed mixer is 20m/s, the temperature of the high-speed mixer is about 220 ℃, and the temperature of the asphalt is about 250 ℃;
the graphite fine powder was added and stirred for 16 minutes. High-temperature liquid-phase pitch high-temperature spraying is carried out after the graphite fine powder is fluidized at a high speed. The spraying speed of the asphalt is 20s per kilogram of asphalt, the spraying pressure is 0.1Mpa, the viscosity of the asphalt is 4000cps, and the temperature is 250 ℃; during spraying, the mixture was stirred while being sprayed at a stirring speed of 20m/s for 19 minutes.
(3) The coated materials enter a coating machine, and the coated materials are shaped, so that the asphalt is more uniform on the surface of the graphite and is completely coated; the stirring linear speed of the wrapping machine is 20m/s, and the time is 18 minutes. The temperature of the wrapping machine was 230 ℃.
(4) And heating the shaped coating material to 2800 ℃ at the speed of 6 ℃/min under the protection of nitrogen in a tubular furnace, preserving the heat for 7h for graphitization treatment, and cooling to room temperature to obtain the liquid-phase coating modified graphite cathode material.
Example 6
(1) And (3) subjecting the solid asphalt to 240 ℃ at high temperature to obtain high-temperature liquid asphalt. And filtering the high-temperature liquid-phase asphalt, wherein the mesh number of the filter screen is 160 meshes.
(2) Spraying and atomizing 30 parts of high-temperature liquid asphalt, coating 950 parts of silicon fine powder with the particle size of 17.8um, and carrying out heat preservation, heating and high-speed mixing in a high-speed mixer, wherein the stirring linear speed of the high-speed mixer is 30m/s, the temperature of the high-speed mixer is about 200 ℃, and the temperature of the asphalt is about 240 ℃;
the silicon fine powder was fluidized at a high speed in a high-speed mixer at a stirring line speed of 30m/s for 7 minutes. High-temperature liquid-phase asphalt high-temperature spraying is carried out after the silicon fine powder is fluidized at a high speed. The spraying speed of the asphalt is 30s per kilogram of asphalt, the spraying pressure is 0.15Mpa, the viscosity of the asphalt is 5000cps, and the temperature is 240 ℃; during spraying, the mixture was stirred while being sprayed at a stirring speed of 30m/s for 16 minutes.
(3) The coated materials enter a coating machine, and the coated materials are shaped, so that the asphalt is more uniform on the surface of the silicon and is completely coated; the stirring linear speed of the wrapping machine was 28m/s and the time was 18 minutes. The temperature of the wrapping machine was 220 ℃.
(4) And heating the shaped wrapping material to 1000 ℃ at the speed of 7 ℃/min under the protection of nitrogen in a tubular furnace, preserving the heat for 6h for carbonization, and cooling to room temperature to obtain the liquid-phase coated modified silicon negative electrode material.
Example 7
(1) And (3) subjecting the solid asphalt to 230 ℃ at high temperature to obtain high-temperature liquid asphalt. And filtering the high-temperature liquid-phase asphalt, wherein the mesh number of the filter screen is 140 meshes.
(2) Spraying and atomizing 30 parts of high-temperature liquid asphalt, coating the high-temperature liquid asphalt on 1000 parts of silicon fine powder with the particle size of 15.8um, and carrying out heat preservation, heating and high-speed mixing in a high-speed mixer, wherein the stirring linear speed of the high-speed mixer is 25m/s, the temperature of the high-speed mixer is about 200 ℃, and the temperature of the asphalt is about 230 ℃;
the silicon fine powder is fluidized at high speed in a high-speed mixer, the stirring linear speed is 25m/s, and the stirring time is 8 minutes. High-temperature liquid-phase asphalt high-temperature spraying is carried out after the silicon fine powder is fluidized at a high speed. The spraying speed of the asphalt is 25s per kilogram of asphalt, the spraying pressure is 0.2Mpa, the viscosity of the asphalt is 10000cps, and the temperature is 230 ℃; during spraying, the mixture was stirred while being sprayed at a stirring speed of 25m/s for 14 minutes.
(3) The coated materials enter a coating machine, and the coated materials are shaped, so that the asphalt is more uniform on the surface of the silicon and is completely coated; the stirring linear speed of the wrapping machine is 28m/s, and the time is 15 minutes. The temperature of the wrapping machine was 210 ℃.
(4) And heating the shaped wrapping material to 2000 ℃ at the speed of 8 ℃/min under the protection of nitrogen in a tubular furnace, preserving the heat for 7h for carbonization, and cooling to room temperature to obtain the liquid-phase coated modified silicon negative electrode material.
Example 8
(1) And (3) subjecting the solid asphalt to 220 ℃ at high temperature to obtain high-temperature liquid asphalt. And filtering the high-temperature liquid-phase asphalt, wherein the mesh number of the filter screen is 150 meshes.
(2) Spraying and atomizing 30 parts of high-temperature liquid asphalt, coating 1050 parts of silica fine powder with the particle size of 13.6um, and carrying out heat preservation, heating and high-speed mixing in a high-speed mixer, wherein the stirring linear speed of the high-speed mixer is 30m/s, the temperature of the high-speed mixer is about 160 ℃, and the temperature of the asphalt is about 220 ℃;
the addition of the fine silica powder was followed by stirring for 7 minutes. High-temperature liquid-phase asphalt high-temperature spraying is carried out after the fine silicon oxide powder is fluidized at a high speed. The spraying speed of the asphalt is 35s per kilogram of asphalt, the spraying pressure is 0.18Mpa, the viscosity of the asphalt is 6000cps, and the temperature is 220 ℃; during spraying, the mixture is stirred while being sprayed, the stirring linear speed is 30m/s, and the stirring time is 15 minutes.
(3) The coated material enters a coating machine to shape the coated material, so that the asphalt is more uniform on the surface of the silica dioxide and is completely coated; the stirring linear speed of the wrapping machine is 30m/s, and the time is 14 minutes. The temperature of the wrapping machine was 160 ℃.
(4) And heating the shaped wrapping material to 2800 ℃ at the speed of 5 ℃/min under the protection of nitrogen in a tubular furnace, preserving the heat for 8h for graphitization treatment, and cooling to room temperature to obtain the liquid-phase coated modified silicon monoxide negative electrode material.
Example 9
(1) And (3) subjecting the solid asphalt to 150 ℃ at high temperature to obtain high-temperature liquid asphalt. And filtering the high-temperature liquid-phase asphalt, wherein the mesh number of the filter screen is 140 meshes.
(2) Spraying and atomizing 30 parts of high-temperature liquid asphalt, coating 950 parts of silica fine powder with the particle size of 13.1um, and carrying out heat preservation, heating and high-speed mixing in a high-speed mixer, wherein the stirring linear speed of the high-speed mixer is 20m/s, the temperature of the high-speed mixer is about 100 ℃, and the temperature of the asphalt is about 150 ℃;
the addition of the fine silica powder was followed by stirring for 7 minutes. High-temperature liquid-phase asphalt high-temperature spraying is carried out after the fine silicon oxide powder is fluidized at a high speed. The spraying speed of the asphalt is 40s per kilogram of asphalt, the spraying pressure is 0.09Mpa, the viscosity of the asphalt is 4000cps, and the temperature is 150 ℃; during spraying, the mixture is stirred while being sprayed, the stirring linear speed is 20m/s, and the time is 12 minutes.
(3) The coated material enters a coating machine to shape the coated material, so that the asphalt is more uniform on the surface of the silica dioxide and is completely coated; the stirring linear speed of the wrapping machine is 25m/s, and the time is 13 minutes. The temperature of the wrapping machine was 110 ℃.
(4) And heating the shaped wrapping material to 3000 ℃ at the speed of 5 ℃/min under the protection of nitrogen in a tubular furnace, preserving heat for 9h for graphitization treatment, and cooling to room temperature to obtain the liquid-phase coated modified silicon monoxide negative electrode material.
Example 10
(1) And (3) carrying out high-temperature 100 ℃ treatment on the solid asphalt to obtain high-temperature liquid asphalt. And filtering the high-temperature liquid-phase asphalt, wherein the mesh number of the filter screen is 110 meshes.
(2) Spraying and atomizing 30 parts of high-temperature liquid asphalt, coating 980 parts of graphite fine powder with the particle size of 12.2um, and carrying out heat preservation, heating and high-speed mixing in a high-speed mixer, wherein the stirring linear speed of the high-speed mixer is 33m/s, the temperature of the high-speed mixer is about 90 ℃, and the temperature of the asphalt is about 100 ℃;
the graphite fine powder is added and then stirred for 8 minutes. High-temperature liquid-phase pitch high-temperature spraying is carried out after the graphite fine powder is fluidized at a high speed. Spraying asphalt at a speed of 35 s/kg asphalt under a pressure of 0.07Mpa at a viscosity of 2000cps at a temperature of 100 deg.C; during spraying, the mixture was stirred while being sprayed at a stirring speed of 33m/s for 13 minutes.
(3) The coated and formed wrapping material enters a wrapping machine, and the wrapping material is shaped, so that the asphalt is more uniform on the graphite surface and is completely wrapped; the stirring linear speed of the wrapping machine was 28m/s and the time was 14 minutes. The temperature of the wrapping machine was 100 ℃.
(4) And heating the shaped wrapping material to 3200 ℃ at the speed of 5 ℃/min under the protection of nitrogen in a tubular furnace, preserving the heat for 10h for graphitization treatment, and cooling to room temperature to obtain the liquid-phase coated modified graphite cathode material.
The testing method of the half-cell comprises the steps of uniformly mixing a modified negative electrode material sample, N-methyl pyrrolidone containing 6-7% of polyvinylidene fluoride and 2% of conductive carbon black, coating the mixture on a copper foil, and putting the coated pole piece into a vacuum drying oven at the temperature of 110 ℃ for vacuum drying for 4 hours for later use. The simulated cell assembly was carried out in a nitrogen-filled german braun glove box, with an electrolyte of 1MLiPF6+ EC: DEC: DMC ═ l: 1: 1 (volume ratio), the metal lithium sheet is a counter electrode, the electrochemical performance test is carried out on a battery tester of ArbinBT2000 type U.S. the charging and discharging voltage range is 0.005-1.0V, and the charging and discharging rate is 0.1C. The data are listed in table 1.
Figure BDA0002630393610000101
The test method of the full cell used in the invention is that the graphite of the embodiment or the comparative example is used as the negative electrode, the lithium cobalt oxide is used as the positive electrode, lM-LiPF6EC: DMC: EMC 1: 1: a full cell was assembled with 1 (volume ratio) solution as the electrolyte and the rate curves of example 10 at different discharge rates were tested as shown in fig. 1.
The modified cathode material produced by the method has excellent electrochemical performance, the first charge-discharge efficiency is up to more than 96%, the rate performance is good, the capacity is high, and the modified cathode material can be applied to high-rate power batteries of electric automobiles, model airplanes, electric tools and the like.

Claims (8)

1. A method for coating a modified negative electrode material by adopting solid asphalt liquid-phase high-temperature spraying is characterized by comprising the following steps:
s1, obtaining high-temperature liquid phase asphalt by the solid asphalt with high softening point at the temperature of 80-300 ℃; filtering the high-temperature liquid-phase asphalt, wherein the mesh number of a filter screen is 100-200 meshes;
s2, mixing 800-1200 parts of graphite fine powder or silicon monoxide fine powder and 10-50 parts of liquid asphalt in parts by weight; firstly, putting graphite fine powder or silicon fine powder or silica fine powder into a high-speed mixer for high-speed fluidization, keeping the temperature of 50-300 ℃, and then spraying high-temperature liquid-phase asphalt into the high-speed mixer at high temperature to coat the graphite fine powder or the silicon fine powder or the silica fine powder;
s3, feeding the coated material into a coating machine, shaping the coated material, and enabling the asphalt to be more uniform and complete in coating on the surface of the graphite fine powder, the silicon fine powder or the silicon monoxide fine powder;
and S4, carrying out high-temperature heat treatment on the shaped coating material under the protection of inert gas in a tube furnace at the heating rate of 2-8 ℃/min, preserving the heat for 3-10 h, and cooling to room temperature to obtain the liquid-phase coating modified negative electrode material.
2. The method for coating the modified negative electrode material by adopting the solid asphalt liquid-phase high-temperature spraying according to claim 1, is characterized in that: fluidizing graphite fine powder or silicon fine powder or silica fine powder at high speed in a high-speed mixer, wherein the stirring speed is 10-42 m/s, and the stirring time is 5-20 minutes; and keeping the temperature at 50-300 ℃; the spraying speed of the asphalt is 20-50 s per kilogram of asphalt, the spraying pressure is 0.05-0.3 Mpa, the viscosity of the asphalt is 1000-10000 cps, and the temperature is 80-250 ℃; during spraying, stirring is carried out while spraying, the stirring linear speed is 10-42 m/s, and the time is 5-20 minutes.
3. The preparation method of the solid asphalt liquid-phase high-temperature spray-coated modified negative electrode material according to claim 1, which is characterized in that: the stirring linear speed of the wrapping machine is 10-42 m/s, and the time is 5-20 minutes.
4. The preparation method of the solid asphalt liquid-phase high-temperature spray-coated modified negative electrode material according to claim 1, which is characterized in that: the temperature of the wrapping machine is 100-300 ℃.
5. The method for coating the modified negative electrode material by adopting the solid asphalt liquid-phase high-temperature spraying according to claim 1, is characterized in that: the high temperature heat treatment in step S4 is carbonization treatment at 1000 to 2000 ℃ or graphitization treatment at 2000 to 3200 ℃.
6. The preparation method of the solid asphalt liquid-phase high-temperature spray-coated modified negative electrode material according to claim 1, which is characterized in that: the inert gas in step S4 is nitrogen gas having a purity of 99% or more.
7. The method for coating the modified negative electrode material by adopting the solid asphalt liquid-phase high-temperature spraying according to claim 1, is characterized in that: the particle size of the graphite fine powder or the silicon oxide fine powder is 12.2-20.2 um.
8. The method for coating the modified negative electrode material by adopting the solid asphalt liquid-phase high-temperature spraying according to claim 7, is characterized in that: the graphite fine powder is one or more of spherical natural graphite, spheroidal natural graphite, crystalline flake graphite, artificial graphite, petroleum coke, pitch coke and mesocarbon microbeads.
CN202010809450.0A 2020-08-12 2020-08-12 Method for coating modified negative electrode material by adopting solid asphalt liquid-phase high-temperature spraying Pending CN114074940A (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108832091A (en) * 2018-06-11 2018-11-16 深圳市贝特瑞新能源材料股份有限公司 A kind of long circulating modified graphite based composites, preparation method and the lithium ion battery comprising the material
CN109956471A (en) * 2019-04-26 2019-07-02 溧阳紫宸新材料科技有限公司 The process for being granulated or coating for graphite cathode material

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108832091A (en) * 2018-06-11 2018-11-16 深圳市贝特瑞新能源材料股份有限公司 A kind of long circulating modified graphite based composites, preparation method and the lithium ion battery comprising the material
CN109956471A (en) * 2019-04-26 2019-07-02 溧阳紫宸新材料科技有限公司 The process for being granulated or coating for graphite cathode material

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