CN113363445A - Reticular gamma-alumina coated modified graphite negative electrode material, and preparation method and application thereof - Google Patents
Reticular gamma-alumina coated modified graphite negative electrode material, and preparation method and application thereof Download PDFInfo
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Abstract
The invention relates to the field of negative electrode materials, in particular to a preparation method of a reticular gamma-alumina coated modified graphite negative electrode material, which comprises the following specific steps: uniformly coating aluminum salt on the surface of a commercial graphite cathode by a sol-gel method; vacuum drying the obtained coated precursor; the dried product is calcined at high temperature to obtain a reticular gamma-alumina coated modified graphite material; the application of the reticular gamma-alumina coated modified graphite cathode is also provided, and the coated modified graphite material is applied to the lithium ion battery cathode; the method has the advantages of simple process, mild conditions and low cost, and the reticular gamma-alumina coated modified graphite cathode material prepared by the method has uniform surface coating, uniform particle size distribution, excellent electrochemical performance and stable product batch property, and is suitable for large-scale industrial production.
Description
Technical Field
The invention relates to the field of negative electrode materials, in particular to a reticular gamma-alumina coated modified graphite negative electrode material, a preparation method and application thereof.
Background
In recent years, lithium ion batteries have been widely used in electric vehicles to alleviate climate change and atmospheric pollution and to promote the conversion of energy systems. However, compared with the traditional fuel automobile, the problems of mileage anxiety, long charging time and the like brought by the new energy automobile seriously affect the experience of consumers and hinder the market development. Therefore, the fast charge performance of the lithium ion battery is very important for the next generation energy storage system.
For a traditional graphite negative electrode, the phenomenon of lithium precipitation is easily caused due to the characteristic of low working potential (< 0.2V), so that the coulombic efficiency of lithium deposition and stripping is lower than that of lithium insertion and stripping, lithium dendrites are formed to penetrate through a battery diaphragm while active lithium ions and electrolyte are continuously consumed, internal short circuit is caused, and potential safety hazards are brought. Although the novel negative electrode material lithium titanate avoids the problem well, the energy density of the battery is seriously reduced due to the defects of high working voltage (1.55V) and low specific capacity (175 mAh/g). Under the influence of the above reasons, the lithium ion battery must have a trade-off between the quick charge performance and the safety performance.
From the basic principle of lithium deintercalation of graphite materials, it is known that the wettability between the electrolyte and the electrode plays a key role in the rate of intercalation of lithium ions. In the preparation process of the battery, in order to maximize the volumetric energy density of the battery, the negative electrode material needs to realize the volumetric filling maximization in a limited space, and therefore, ensuring that enough electrolyte can quickly wet the whole electrode is an important strategy for improving the quick charging performance of the battery. In order to solve the problems, the invention uniformly coats a reticular gamma-alumina coating on the surface of graphite by a simple sol-gel coating process. The good wettability of the coating can greatly improve the compatibility of the graphite material and the electrolyte, and meanwhile, the special network structure and the developed pore size distribution of the gamma-alumina can also provide an effective de-intercalation channel for lithium ions. The reticular gamma-alumina coated modified graphite material prepared by the method can improve the electrochemical reaction kinetic rate of the cathode material on the premise of not sacrificing safety, and in addition, the alumina serving as an excellent flame retardant material can absorb heat when extreme chemical reaction occurs in the battery, so that thermal runaway is avoided, and the safety performance of the battery is improved.
Disclosure of Invention
In order to solve the technical problems, the invention provides a reticular gamma-alumina coated modified graphite cathode material, which effectively improves the compatibility of the graphite material and electrolyte, and improves the dynamic performance of the graphite material while considering the safety performance.
The invention also provides a preparation method and application of the reticular gamma-alumina coated modified graphite cathode material, and the preparation method has the advantages of simple synthesis process, low cost, easiness in expansion and higher application prospect.
The invention adopts the following technical scheme:
a preparation method of a reticular gamma-alumina coated modified graphite negative electrode material comprises the following steps:
(1) dispersing a certain mass of graphite in deionized water, uniformly stirring, and marking as solution A;
(2) dissolving a certain mass of aluminum salt in deionized water, and marking as a solution B;
(3) slowly dripping the solution B into the solution A under the mechanical stirring; adding a certain amount of alkaline material to adjust the pH value, and reacting at room temperature to obtain sol slurry;
(4) aging and reacting the slurry prepared in the step (3) at the temperature of 50-120 ℃ for 2-14 h to form gel, and performing vacuum drying and crushing treatment to obtain a coating precursor;
(5) calcining the precursor obtained in the step (4) at 600-1100 ℃ for 2-6 h under an inert atmosphere, cooling the product to room temperature, and crushing and screening to obtain the reticular gamma-alumina coated modified graphite cathode material with the reticular gamma-alumina uniformly coated on the surface of graphite particles.
The technical scheme is further improved in that the consumption of the graphite is 20-100 times of that of the generated reticular gamma-alumina.
The technical scheme is further improved in that in the step (1), the stirring speed is 100-500 rpm, and the stirring time is 0.5-3 h.
In a further improvement of the above technical solution, in the step (2), the aluminum salt includes an inorganic aluminum salt and an organic aluminum salt.
The technical scheme is further improved in that in the step (3), the stirring speed is 100-500 rpm, the alkaline material is one of ammonia water, urea, formamide, sodium hydroxide, potassium hydroxide, sodium bicarbonate and potassium bicarbonate, the pH value is 5-8, the room temperature is 0-50 ℃, and the sol reaction time is 5-14 hours.
The technical scheme is further improved in that in the step (4), the temperature of the vacuum drying is 50-110 ℃, and the time is 10-24 hours.
The technical scheme is further improved in that the inert gas is nitrogen, argon or helium, the gas flow rate is 1-2L/h, the calcining temperature is 600-1100 ℃, the heating rate is 1-10 ℃/min, the time is 2-6 h, the grinding is carried out by adopting a conventional grinder, the screening is carried out by adopting a screen with more than 325 meshes, and undersize materials are taken.
The technical scheme is further improved in that the concentration of aluminum ions in the reaction system is 0.1-0.8M.
A reticular gamma-alumina coated modified graphite negative electrode material is prepared by the preparation method.
The application of the reticular gamma-alumina coated modified graphite cathode material is applied to the cathode material of a lithium battery.
The invention has the beneficial effects that:
the invention uniformly coats the surface of the graphite particles with the reticular gamma-alumina by a simple and low-cost sol-gel method. By virtue of the synergistic effect of the aluminum oxide network nano structure and developed pores, the lithium intercalation kinetics of the coated modified graphite material is remarkably improved. It is worth noting that the microstructure and the specific surface area of the surface coating agent can be effectively regulated and controlled by regulating the heat treatment temperature and the pH value of the reaction system, so that the energy density and the quick charging performance of the graphite cathode can be regulated. In addition, the synthesis process of the alumina coating based on the sol-gel method is simple, the cost is low, the expansion is easy, the reticular gamma-alumina coated modified graphite material prepared by the process has stable structure, strong binding capacity of the coating agent and the aggregate surface and small capacity loss, is a negative electrode material which gives consideration to both energy density and dynamics, and has higher application prospect.
Drawings
Fig. 1 is an SEM image of the material of example 1 of the reticulated gamma-alumina coated modified graphite anode material of the present invention;
fig. 2 is a high-magnification SEM image of the material of example 1 of the reticulated gamma-alumina coated modified graphite anode material of the present invention;
FIG. 3 is an X-ray diffraction pattern of reticulated gamma-alumina of example 1 of a reticulated gamma-alumina coated modified graphite negative electrode material of the present invention;
fig. 4 is a graph of capacity voltage differential for the material of example 1 in which the reticulated gamma-alumina coated modified graphite anode material of the present invention was used.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and the scope of the present invention includes but is not limited to the following embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A preparation method of a reticular gamma-alumina coated modified graphite negative electrode material comprises the following steps:
(1) dispersing a certain mass of graphite in deionized water, uniformly stirring, and marking as solution A;
(2) dissolving a certain mass of aluminum salt in deionized water, and marking as a solution B;
(3) slowly dripping the solution B into the solution A under the mechanical stirring; adding a certain amount of alkaline material to adjust the pH value, and reacting at room temperature to obtain sol slurry;
(4) aging and reacting the slurry prepared in the step (3) at the temperature of 50-120 ℃ for 2-14 h to form gel, and performing vacuum drying and crushing treatment to obtain a coating precursor;
(5) calcining the precursor obtained in the step (4) at 600-1100 ℃ for 2-6 h under an inert atmosphere, cooling the product to room temperature, and crushing and screening to obtain the reticular gamma-alumina coated modified graphite cathode material with the reticular gamma-alumina uniformly coated on the surface of graphite particles.
The using amount of the graphite is 20-100 times of that of the designed gamma-alumina, and preferably 100 times; the stirring speed is 100-500 rpm, and more preferably 400 rpm; the stirring time is 0.5-3 h, preferably 2 h.
In the step (2), the aluminum salt includes inorganic aluminum salts and organic aluminum salts, preferably aluminum nitrate, aluminum acetate, aluminum oxalate, aluminum sulfate, aluminum n-butoxide, aluminum sec-butoxide, and more preferably aluminum nitrate.
In the step (3), the stirring speed is 100-500 rpm, preferably 400 rpm; the alkaline material is preferably ammonia water, urea, formamide, sodium hydroxide, potassium hydroxide and sodium bicarbonate, more preferably urea and ammonia water, and still more preferably ammonia water; the pH is 5-8, preferably 7; the room temperature is 0-50 ℃, and preferably 35 ℃; the sol reaction time is 3-12 h, preferably 6 h.
In the step (4), the aging temperature is 50-120 ℃, preferably 80 ℃; the aging time is 2-14 h, preferably 8 h; the vacuum drying temperature is 50-120 ℃, and the optimal temperature is 100 ℃; the time is 6-12 h, preferably 8 h; the coarse crushing is treated by a conventional mechanical crusher.
The coating method can select a hydrothermal method, a coprecipitation method, a chemical immersion plating method or a sol-gel method, preferably a sol-gel method, and specifically comprises the steps of dispersing or dissolving pre-coated graphite and active aluminum salt in water according to a certain proportion, adding weak base to promote hydrolysis of the aluminum salt to form sol, carrying out aging reaction at 80 ℃ for 8 hours to obtain gel, and drying the gel at 100 ℃ in vacuum for 8 hours to obtain the coated modified graphite precursor.
In the step (5), the calcining process and conditions are conventional processes and conditions in the field; the inert gas is one or more of nitrogen, argon and helium, preferably nitrogen, and the gas flow rate is 1-2L/h, preferably 1.5L/h; the calcination temperature is preferably 600-1100 ℃, and more preferably 900 ℃; the calcination time is preferably 2 to 6 hours, more preferably 3 hours; the room temperature is 0-40 ℃ of ambient temperature; preferably 35 ℃; the crushing process is a conventional crushing process in the field, and preferably adopts mechanical grinding, jet milling, planetary ball mill crushing or fluidized bed grinding, and more preferably adopts mechanical grinding; the crushing standard is that the average particle size of the material is 1-40 mu m; the screening process comprises the steps of screening through a 325-mesh screen and taking undersize products.
Further, the concentration of aluminum ions in the reaction system is 0.1-0.8M, preferably 0.2M.
Further, the temperature rise rate of the calcination is 1-10 ℃/min, preferably 2 ℃/min.
The invention prepares a reticular gamma-alumina coated modified graphite material based on a sol-gel method, which benefits from the good ionic conductivity and excellent wettability of gamma-alumina, the SOC of lithium separated from the coated modified graphite material under the charging rate of 3C can reach 33 percent, which is improved by 18 percent compared with aggregate, and the gram capacity of the material before and after modification is reduced by 3.1mAh/g, and the first coulombic efficiency is basically unchanged, so that the material is a graphite cathode material which gives consideration to quick charge and energy density.
A reticular gamma-alumina coated modified graphite cathode is prepared from the following preparation processes: firstly, dispersing a graphite raw material in a solvent, and slowly dripping an aluminum salt aqueous solution after the system is uniformly stirred; then, adjusting the pH value to be neutral by using weak base, and reacting at room temperature until alumina sol is formed; and then heating the system, carrying out aging reaction for a certain time to obtain aluminum gel, carrying out vacuum drying and desolventizing, and then placing the aluminum gel in a tubular furnace for high-temperature heat treatment to obtain the reticular gamma-alumina coated modified graphite.
Preferably, the solvent is deionized water.
Preferably, the aluminum salt includes inorganic aluminum salts and organic aluminum salts, preferably aluminum nitrate, aluminum acetate, aluminum oxalate, aluminum sulfate, aluminum n-butoxide, aluminum sec-butoxide, and more preferably aluminum nitrate.
Preferably, the high-temperature heat treatment is a heat treatment of the coating precursor in an atmosphere containing an inert gas.
Example 1
(1) Preparation of coated precursor
600g of graphite is dispersed in 500ml of deionized water, and mechanical stirring is carried out at 400rpm for homogenizing for 2 h; then 100ml of an aqueous solution in which 44.6g of aluminum nitrate nonahydrate is dissolved is slowly dropped; then 29ml of strong ammonia water is dripped into the system to adjust the pH value to 7, and the mixture reacts for 6 hours at room temperature to form aluminum sol; and finally, heating to 80 ℃, carrying out aging reaction for 8h to form aluminum gel, carrying out vacuum drying and desolventizing at 100 ℃ for 8h, and mechanically crushing to obtain the aluminum hydroxide coated graphite precursor.
(2) Preparation of reticular gamma-alumina coated modified graphite material
Placing the aluminum hydroxide coated graphite precursor obtained in the step (1) in a vacuum tube furnace, heating to 900 ℃ in a nitrogen atmosphere, wherein the heating rate is 2 ℃/min, and the heat preservation time is 3 h; after the furnace temperature is reduced to room temperature, the reticular gamma-alumina coated modified graphite material is obtained by crushing and screening (325 meshes).
Example 2
(1) Preparation of coated precursor
600g of graphite is dispersed in 500ml of deionized water, and mechanical stirring is carried out at 400rpm for homogenizing for 2 h; then 100ml of an aqueous solution in which 89.2g of aluminum nitrate nonahydrate was dissolved was slowly dropped; then 58ml of concentrated ammonia water is dripped into the system to adjust the pH value to 7, and the mixture reacts for 6 hours at room temperature to form aluminum sol; and finally, heating to 80 ℃, carrying out aging reaction for 8h to form aluminum gel, carrying out vacuum drying and desolventizing at 100 ℃ for 8h, and mechanically crushing to obtain the aluminum hydroxide coated graphite precursor.
(2) Preparation of reticular gamma-alumina coated modified graphite material
Placing the aluminum hydroxide coated graphite precursor obtained in the step (1) in a vacuum tube furnace, heating to 900 ℃ in a nitrogen atmosphere, wherein the heating rate is 2 ℃/min, and the heat preservation time is 3 h; after the furnace temperature is reduced to room temperature, the reticular gamma-alumina coated modified graphite material is obtained by crushing and screening (325 meshes).
Example 3
(1) Preparation of coated precursor
600g of graphite is dispersed in 500ml of deionized water, and mechanical stirring is carried out at 400rpm for homogenizing for 2 h; then 100ml of an aqueous solution in which 133.8g of aluminum nitrate nonahydrate was dissolved was slowly dropped; then, 87ml of concentrated ammonia water is dripped into the system to adjust the pH value to 7, and the mixture reacts for 6 hours at room temperature to form aluminum sol; and finally, heating to 80 ℃, carrying out aging reaction for 8h to form aluminum gel, carrying out vacuum drying and desolventizing at 100 ℃ for 8h, and mechanically crushing to obtain the aluminum hydroxide coated graphite precursor.
(2) Preparation of reticular gamma-alumina coated modified graphite material
Placing the aluminum hydroxide coated graphite precursor obtained in the step (1) in a vacuum tube furnace, heating to 900 ℃ in a nitrogen atmosphere, wherein the heating rate is 2 ℃/min, and the heat preservation time is 3 h; after the furnace temperature is reduced to room temperature, the reticular gamma-alumina coated modified graphite material is obtained by crushing and screening (325 meshes).
Example 4
(1) Preparation of coated precursor
600g of graphite is dispersed in 500ml of deionized water, and mechanical stirring is carried out at 400rpm for homogenizing for 2 h; then 100ml of an aqueous solution in which 44.6g of aluminum nitrate nonahydrate is dissolved is slowly dropped; then 29ml of strong ammonia water is dripped into the system to adjust the pH value to 7, and the mixture reacts for 6 hours at room temperature to form aluminum sol; and finally, heating to 80 ℃, carrying out aging reaction for 8h to form aluminum gel, carrying out vacuum drying and desolventizing at 100 ℃ for 8h, and mechanically crushing to obtain the aluminum hydroxide coated graphite precursor.
(2) Preparation of reticular gamma-alumina coated modified graphite material
Placing the aluminum hydroxide coated graphite precursor obtained in the step (1) in a vacuum tube furnace, heating to 700 ℃ in a nitrogen atmosphere, wherein the heating rate is 2 ℃/min, and the heat preservation time is 3 h; after the furnace temperature is reduced to room temperature, the reticular gamma-alumina coated modified graphite material is obtained by crushing and screening (325 meshes).
Example 5
(1) Preparation of coated precursor
600g of graphite is dispersed in 500ml of deionized water, and mechanical stirring is carried out at 400rpm for homogenizing for 2 h; then 100ml of an aqueous solution in which 44.6g of aluminum nitrate nonahydrate is dissolved is slowly dropped; then 29ml of strong ammonia water is dripped into the system to adjust the pH value to 7, and the mixture reacts for 6 hours at room temperature to form aluminum sol; and finally, heating to 80 ℃, carrying out aging reaction for 8h to form aluminum gel, carrying out vacuum drying and desolventizing at 100 ℃ for 8h, and mechanically crushing to obtain the aluminum hydroxide coated graphite precursor.
(2) Preparation of reticular gamma-alumina coated modified graphite material
Placing the aluminum hydroxide coated graphite precursor obtained in the step (1) in a vacuum tube furnace, heating to 1100 ℃ in a nitrogen atmosphere, wherein the heating rate is 2 ℃/min, and the heat preservation time is 3 h; after the furnace temperature is reduced to room temperature, the reticular gamma-alumina coated modified graphite material is obtained by crushing and screening (325 meshes).
Example 6
(1) Preparation of coated precursor
600g of graphite is dispersed in 500ml of deionized water, and mechanical stirring is carried out at 400rpm for homogenizing for 2 h; then 100ml of an aqueous solution in which 44.6g of aluminum nitrate nonahydrate is dissolved is slowly dropped; finally, drying and desolventizing for 8h in vacuum at 100 ℃ and mechanically crushing to obtain the aluminum nitrate coated graphite precursor.
(2) Preparation of reticular gamma-alumina coated modified graphite material
Placing the aluminum nitrate-coated graphite precursor obtained in the step (1) in a vacuum tube furnace, heating to 900 ℃ in a nitrogen atmosphere, wherein the heating rate is 2 ℃/min, and the heat preservation time is 3 h; after the furnace temperature is reduced to room temperature, the reticular gamma-alumina coated modified graphite material is obtained by crushing and screening (325 meshes).
Example 7
(1) Preparation of coated precursor
600g of graphite is dispersed in 500ml of deionized water, and mechanical stirring is carried out at 400rpm for homogenizing for 2 h; then 100ml of an aqueous solution in which 44.6g of aluminum nitrate nonahydrate is dissolved is slowly dropped; then 58ml of strong ammonia water is dripped into the system to adjust the pH value to 12, and the reaction is carried out for 6 hours at room temperature; and finally, heating to 80 ℃ for reaction for 8h, then carrying out vacuum drying and desolventizing for 8h at 100 ℃ and mechanically crushing to obtain the aluminum hydroxide coated graphite precursor.
(2) Preparation of reticular gamma-alumina coated modified graphite material
Placing the aluminum hydroxide coated graphite precursor obtained in the step (1) in a vacuum tube furnace, heating to 900 ℃ in a nitrogen atmosphere, wherein the heating rate is 2 ℃/min, and the heat preservation time is 3 h; after the furnace temperature is reduced to room temperature, the reticular gamma-alumina coated modified graphite material is obtained by crushing and screening (325 meshes).
The particle size and specific surface area of the coated modified graphite anode materials of examples 1 to 7 were measured, and the results are shown in table 1. The particle size test is carried out on a Malvern laser particle size analyzer MS 2000; the specific surface area was measured by the Congta specific surface area measuring apparatus NOVA2000 e.
TABLE 1
Specific capacity and charging SOC tests were performed on the coated modified graphite obtained in examples 1 to 7 by a conventional half-cell test method, and the results are shown in table 1. The specific test method comprises the following steps: uniformly mixing the reticular gamma-alumina coated modified graphite, 6% polyvinylidene fluoride N-methyl pyrrolidone solution and conductive carbon black according to a mass ratio of 90:5:5, coating the mixture on a conductive copper foil, and then carrying out vacuum drying treatment on the pole piece at 100 ℃ for 12 hours; subsequently, the button cell is assembled in an Itex glove box, the selected electrolyte consists of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate in a volume ratio of 1:1:1, and 1M LiPF is added6The counter electrode adopts a metal lithium sheet, the whole test is completed on the American Arbin electrochemical detection system, and the voltage window is 0V-2.0V.
From the electrochemical data of the products obtained in examples 1 to 3, it can be seen that the content of the coating agent alumina has an important influence on the specific capacity and the charging SOC of the final product, and since the alumina itself does not provide capacity, the specific capacity of the material decreases with the increase of the coating amount. Conversely, as the surface alumina coating increases, the wettability of the graphite with the electrolyte and the kinetics of the electrochemical reaction of the material increase correspondingly. Comparative examples 1, 4 and 5 show that the heat treatment temperature also has a great influence on the quick charge performance of the material, which is attributed to the difference of the specific surface area and the phase structure of alumina at different temperatures, and the alumina cannot form a network structure at lower temperature, so that the specific surface area is lower, the pore distribution is not developed, and the transmission of lithium ions at the interface of the negative electrode is influenced; when the temperature is increased to 1100 ℃, the alumina is changed from gamma type to alpha type, and the ionic conductivity is sharply reduced.
Analysis of the data from examples 1, 6 and 7 reveals that the amount of ammonia added during the reaction (i.e. the pH of the system) has a major influence on the kinetic properties of the product, since the pH of the system is decisive for the formation of the sol-gel. When no ammonia water is added or excessive ammonia water is added, the aluminum nitrate can not form sol-gel, so that the aluminum nitrate is seriously agglomerated in the heat treatment process, the coating effect is poor, and the dynamic performance of the material is further influenced.
It will be evident to those skilled in the art that the invention includes, but is not limited to, the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should consider the description as a whole, and the embodiments may be appropriately combined to form other embodiments understood by those skilled in the art.
Claims (10)
1. A preparation method of a reticular gamma-alumina coated modified graphite negative electrode material is characterized by comprising the following steps:
(1) dispersing a certain mass of graphite in deionized water, uniformly stirring, and marking as solution A;
(2) dissolving a certain mass of aluminum salt in deionized water, and marking as a solution B;
(3) slowly dripping the solution B into the solution A under the mechanical stirring; adding a certain amount of alkaline material to adjust the pH value, and reacting at room temperature to obtain sol slurry;
(4) aging and reacting the slurry prepared in the step (3) at the temperature of 50-120 ℃ for 2-14 h to form gel, and performing vacuum drying and crushing treatment to obtain a coating precursor;
(5) calcining the precursor obtained in the step (4) at 600-1100 ℃ for 2-6 h under an inert atmosphere, cooling the product to room temperature, and crushing and screening to obtain the reticular gamma-alumina coated modified graphite cathode material with the reticular gamma-alumina uniformly coated on the surface of graphite particles.
2. The preparation method of the reticular gamma-alumina coated modified graphite cathode material as claimed in claim 1, wherein the amount of the graphite is 20-100 times of that of the reticular gamma-alumina.
3. The preparation method of the reticular gamma-alumina coated modified graphite anode material as claimed in claim 1, wherein in the step (1), the stirring speed is 100-500 rpm, and the stirring time is 0.5-3 h.
4. The method for preparing a reticulated γ -alumina-coated modified graphite anode material according to claim 1, wherein in the step (2), the aluminum salt includes an inorganic aluminum salt and an organic aluminum salt.
5. The method for preparing the reticular gamma-alumina coated modified graphite anode material according to claim 1, wherein in the step (3), the stirring speed is 100-500 rpm, the alkaline material is one of ammonia water, urea, formamide, sodium hydroxide, potassium hydroxide, sodium bicarbonate and potassium bicarbonate, the pH is 5-8, the room temperature is 0-50 ℃, and the sol reaction time is 5-14 h.
6. The preparation method of the reticular gamma-alumina coated modified graphite anode material as claimed in claim 1, wherein in the step (4), the temperature of the vacuum drying is 50-110 ℃ and the time is 10-24 h.
7. The preparation method of the reticular gamma-alumina coated modified graphite cathode material as claimed in claim 1, wherein the inert gas is nitrogen, argon or helium, the gas flow rate is 1-2L/h, the calcining temperature is 600-1100 ℃, the heating rate is 1-10 ℃/min, the time is 2-6 h, the pulverization is carried out by a conventional pulverizer, the sieving is carried out by a sieve with more than 325 meshes, and the undersize is taken.
8. The preparation method of the reticular gamma-alumina coated modified graphite cathode material as claimed in claim 1, wherein the concentration of aluminum ions in the reaction system is 0.1-0.8M.
9. A reticulated gamma-alumina coated modified graphite anode material, characterized in that it is produced using the production method according to any one of claims 1 to 8.
10. The application of the reticular gamma-alumina coated modified graphite cathode material is characterized in that the reticular gamma-alumina coated modified graphite cathode material is applied to a lithium battery cathode material.
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| CN114883551A (en) * | 2022-07-11 | 2022-08-09 | 深圳索理德新材料科技有限公司 | Alumina-coated nano silicon and continuous preparation method and system thereof |
| CN117727870A (en) * | 2024-02-18 | 2024-03-19 | 深圳海辰储能科技有限公司 | Negative electrode sheet, secondary battery, battery pack, and power consumption device |
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