CN110739446A - silicon/carbon composite negative electrode material and preparation method thereof - Google Patents
silicon/carbon composite negative electrode material and preparation method thereof Download PDFInfo
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Abstract
The invention relates to silicon/carbon composite cathode materials and a preparation method thereof, wherein the preparation method of the silicon/carbon composite cathode materials comprises the following steps of mixing a chelating agent, a transition metal salt and water, heating and stirring to obtain a chelate, adding a silicon material into the chelate to obtain a mixture, stirring and heating the mixture to evaporate water to obtain sol gel, drying to obtain dry gel, burning the dry gel in an inert atmosphere, annealing and crushing to obtain the silicon/carbon composite cathode material.
Description
Technical Field
The invention relates to the field of lithium ion batteries, in particular to silicon/carbon composite negative electrode materials and a preparation method thereof.
Background
Because the extraction of non-renewable resources (such as natural gas, coal and oil) is kept in energy crisis for a long time without control, and the transitional use of the non-renewable resources causes series pollution to the environment, along with the aggravation of energy shortage and environmental pollution, the development of electric automobiles is more and more rapid, and the lithium ion battery with high capacity, high power and long cycle life is also urgently important.
The graphite material has been widely used in because of the advantages of stable structure and cycle performance, high conductivity and the like, but the capacity requirement of the lithium ion battery is higher and higher with the continuous development of the society, and the theoretical specific capacity of the traditional graphite material is only 372mAh/g, which cannot meet the market requirement, so that the search for high-capacity materials to replace the traditional graphite material is favored.
Silicon-based materials have attracted the attention of researchers successfully due to their theoretical specific capacity as high as 4200mAh/g and abundant resources, and silicon is considered to be the next generation of lithium ion battery materials after traditional graphite, but in Li+In addition, of SEI film formed in the process of lithium intercalation of silicon can lead the silicon surface to be exposed and directly contacted with electrolyte due to the cracking and the pulverization of the silicon structure, and the SEI film is formed again, finally the SEI film is thicker and the electrolyte is continuously consumed, and the defects of the silicon material limit the large scale of the silicon material in the lithium ion battery industryAnd (4) applying the model. Therefore, researchers have attempted to overcome these drawbacks of silicon materials by means of nanocrystallization, carbon coating, silicon-carbon compounding, and silicon alloying.
Due to the fact that the silicon material is in the process of lithium removal/lithium insertion Li+Researchers improve the defect of silicon by compounding silicon and a carbon material to form a silicon/carbon composite material, wherein generally comprises the steps of simply coating carbon to cover a silicon surface with carbon layers, using the carbon layers as a buffer layer and a protective layer, and then fusing the silicon coated with the carbon layers and graphite to form the silicon/carbon composite material.
Chinese patent application CN107785560A discloses high-performance silicon-carbon negative electrode materials and a preparation method thereof, wherein the preparation method comprises the steps of mixing silicon nanocrystallization and graphite, coating the mixture with asphalt, and sintering the mixture to obtain the high-performance silicon-carbon composite negative electrode material.
Disclosure of Invention
The invention aims to solve the problems of low capacity and unstable electrochemical performance of the conventional silicon-carbon negative electrode material, and provides silicon/carbon composite negative electrode materials and a preparation method thereof.
The specific scheme is as follows:
A preparation method of silicon/carbon composite anode material, comprising the following steps:
step 1: mixing a chelating agent, a transition metal salt and water, heating and stirring to obtain a chelate;
step 2: adding a silicon material into the chelate obtained in the step 1 to obtain a mixture;
and step 3: heating the mixture obtained in the step 2 while stirring to evaporate water to obtain sol-gel;
and 4, step 4: drying the sol gel prepared in the step 3 to obtain dry gel;
and 5: and (4) burning the xerogel obtained in the step (4) in an inert atmosphere, and annealing to obtain the silicon/carbon composite cathode material.
, the mole ratio of the chelating agent to the transition metal salt in step 1 is 1:1-4: 1;
optionally, the chelating agent is any of oxalic acid, acetic acid, citric acid, lauric acid, tartaric acid, gluconic acid, ethylenediamine tetraacetic acid, triethanolamine and ethylenediamine;
optionally, the transition metal salt is selected from any kinds of iron salt, ferrous salt, cobalt salt, manganese salt, nickel salt and copper salt;
optionally, the transition metal salt is kinds of iron nitrate, ferric sulfate, ferric chloride, ferrous nitrate, ferrous sulfate, ferrous chloride, cobalt nitrate, cobalt acetate, cobalt oxalate, cobalt sulfate, cobalt chloride, manganese chloride, nickel nitrate, nickel sulfate, nickel chloride, copper sulfate, copper chloride, copper nitrate and copper fluoride;
optionally, the mass ratio of the silicon material in the step 2 to the chelating agent in the step 1 is 2:1-5: 1;
optionally, the silicon material in step 2 is silicon or silicon oxide.
, step 3 includes 3a) heating the mixture obtained in step 2 while stirring, stopping heating when the water content is evaporated to the residual 40-50 wt% of water, and 3b) continuing to evaporate the water content to the residual 20-35 wt% of water by using the residual temperature to obtain the sol-gel.
And , drying at 60-100 deg.C for 12-48h in step 4.
, step 5 includes 5a) heating the tube furnace to 200-300 ℃ under inert atmosphere, closing the inert gas, then pushing the dry gel obtained in step 4 into the tube furnace, 5b) heating to 450-550 ℃ when no bubble emerges from the end of the gas outlet of the tube furnace, keeping the temperature for 40-80min, self-burning the dry gel, 5c) stopping heating, introducing inert gas for assisting cooling, cooling to room temperature, collecting a sample, and crushing to obtain the silicon/carbon composite cathode material.
The invention also protects silicon/carbon composite anode materials, which are prepared by the preparation method of the silicon/carbon composite anode material.
, the average pore diameter of the silicon/carbon composite negative electrode material is 2-8 microns, and the porosity is 30-96%.
The invention also protects negative active materials, which comprise the silicon/carbon composite negative electrode material.
The invention also protects lithium ion battery negative plates, which comprise a negative current collector and active materials distributed on the negative current collector, wherein the active materials comprise the negative active materials.
The invention also protects lithium ion batteries, which comprises a positive plate, a negative plate, an isolating membrane arranged between the positive plate and the negative plate, and electrolyte, wherein the negative plate is the negative plate of the lithium ion battery.
Has the advantages that:
the invention utilizes the method of combining complexation, mechanical mixing, low-temperature drying and burning-annealing to prepare the silicon/carbon composite cathode material, has less process equipment, simple process flow and low manufacturing cost, is beneficial to pushing , and the obtained silicon/carbon composite cathode material has higher capacity and cycle stability, the invention forms carbon solid through burning-annealing, embeds the silicon material in carbon material by using of loose porous carbon solid, coats layers of carbon material on the surface of silicon material in , and well overcomes the problems of low conductivity of silicon material and volume expansion of silicon material in the process of de-embedding+Therefore, the coulombic efficiency of the battery is improved, favorable conditions are created for the performance of the high-capacity lithium ion battery, the capacity of the silicon-based material is truly exerted, conditions are created for application of the silicon-based negative electrode material, and the prepared silicon-carbon composite material has broad application value in the field of the high-energy-density lithium ion battery.
According to preferred embodiments of the invention, in the process of preparing silicon/carbon composite anode materials, a method combining a sol-gel method, a self-combustion method and a mechanical mixing method is adopted, so that the raw material cost is low, the process equipment is simple, the production process is stable and reliable, the industrial production is easy, and the market prospect is good.
Drawings
In order to illustrate the technical solution of the present invention more clearly, the drawings will be briefly described, and it is obvious that the drawings in the following description relate to embodiments of the present invention only, and are not intended to limit the present invention.
FIG. 1 is an image of embodiments of the present invention providing a chelate xerogel before self-combustion annealing;
FIG. 2 is an image of a chelate xerogel provided by embodiments of the present invention after self-combustion annealing;
fig. 3 is an SEM image of a silicon/carbon composite anode material provided by examples of the present invention;
FIG. 4 is a charge-discharge curve of the silicon/carbon composite anode material provided by the invention under different cycle times;
fig. 5 is a curve of the charge-discharge cycle performance of the battery provided by the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein.
In the present invention, the related terms are defined as follows:
the silicon-based material is used as a battery negative electrode material, wherein the silicon is mainly used as an active substance to provide capacity, and the carbon is used as a dispersing matrix to limit the volume change of silicon particles and is used as a conductive network.
The chelating agent provided by the invention is a reagent which contains two or more than two coordination atoms and can generate a complex with a cyclic structure with other ions, and is preferably any kinds of oxalic acid, acetic acid, citric acid, lauric acid, tartaric acid, gluconic acid, ethylene diamine tetraacetic acid, triethanolamine and ethylenediamine.
The transition metal salt in the invention is a salt formed by series metal elements in d region of the periodic table, the transition metal can easily form a complex with the chelating agent in the invention due to the existence of the empty d orbit, and the transition metal salt in the invention is preferably a salt of iron, titanium, cobalt, manganese, copper and nickel, such as iron nitrate, iron sulfate, ferric chloride, ferrous nitrate, ferrous sulfate, ferrous chloride, cobalt nitrate, cobalt acetate, cobalt oxalate, cobalt sulfate, cobalt chloride, manganese chloride, nickel nitrate, nickel sulfate, nickel chloride and copper fluoride, wherein kinds of the transition metal salt are arbitrary.
The silicon material in the invention is silicon or silicon oxide, and the preferable molecular formula is SiOx(x is 0-2), and more preferably at least silicon materials among metal silicon powder, silicon oxide and silicon dioxide, wherein the silicon materials provide silicon sources, and in order to ensure the mixing effect with the chelate, solid inorganic silicon sources are preferred, and the uniform mixing can be realized through mechanical mixing.
For example, in the inert atmosphere, the tube furnace is firstly heated to 200-.
The present invention will be described in detail below by way of examples. The examples do not specify particular techniques or conditions, and are performed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.
The test methods used below included:
testing of the battery: charging and discharging tests are carried out by adopting a Wuhan blue battery test system under the multiplying power of 1C, the battery is tested at the constant temperature of 25 ℃, and the test voltage interval is 0.001-1.5V.
And (4) SEM test: scanning electron microscope JEOL, ZEISS EVO50, acceleration voltage 20KV, working distance 8 mm.
Example 1
The preparation method of the silicon/carbon composite anode material comprises the following steps:
step 1: and (3) according to molar ratio: 4, accurately weighing cobalt nitrate hexahydrate and Ethylene Diamine Tetraacetic Acid (EDTA), adding the cobalt nitrate hexahydrate into a 500ml beaker, adding a 200ml deionized water glass rod, stirring until the cobalt nitrate is completely dissolved (the solution is red), adding the EDTA (insoluble in water), and heating to dissolve the EDTA (the solution is purple) to obtain a chelate;
step 2: adding metal silicon powder into the chelate, wherein the mass ratio of the silicon powder to the EDTA in the step 1 is 7: 2, obtaining a mixture;
step 3, heating and stirring by using a magnetic stirrer with heating, stopping heating when the water in the mixture is evaporated to the remaining half , and continuously evaporating the water to the remaining half by using the remaining temperature to obtain sol gel;
and 4, step 4: drying the sol-gel obtained in the step 3 in a drying oven at 80 ℃ for 30h to obtain dry gel which is purple solid as shown in figure 1;
and 5: and (3) putting the xerogel prepared in the step (4) into a quartz tube for self-combustion-annealing treatment, heating the furnace to 250 ℃ under an inert atmosphere, closing inert gas, then pushing the sample into a temperature zone until no bubbles emerge from the tail end of a gas outlet, heating to 500 ℃, keeping the temperature for 60min, stopping heating, introducing the inert gas for auxiliary cooling, and collecting the sample when the temperature is reduced to room temperature to obtain the silicon/carbon composite cathode material which is a porous black carbonaceous solid and has fluffy appearance characteristics as shown in figure 2.
An SEM image (figure 3) of the silicon/carbon composite negative electrode material shows that the silicon/carbon composite negative electrode material has a porous structure, namely when a silicon material and a chelate compound are mixed to form a dry gel, fluffy space of the dry gel provides a place for silicon, a carbon protective layer can be coated on the surface of the silicon material after self-combustion annealing in the aspect of , the conductivity of the silicon material is increased, in addition, space is reserved for volume change of the silicon material in the process of lithium ion desorption and insertion by forming fluffy and porous carbonaceous solid in the aspect of , the capacity of the silicon material is favorably exerted, the stability of the silicon material is maintained, and therefore the high-capacity lithium ion.
Example 2
The preparation method of the silicon/carbon composite anode material comprises the following steps:
step 1: according to the mol ratio of 1: 2, weighing nickel nitrate and ethylenediamine, adding nickel nitrate into a 500ml beaker, adding 200ml deionized water glass rod, stirring until the nickel nitrate is completely dissolved, adding ethylenediamine, and heating to obtain a chelate;
step 2, adding silicon oxide into the chelate, wherein the mass ratio of silicon oxide to the ethylenediamine in the step 1 is 3: 1, so as to obtain a mixture;
and step 3: heating and stirring by using a magnetic stirrer with heating, stopping heating when water in the mixture is evaporated to the residual water of 40 wt%, and continuously evaporating the water to the residual water of 35 wt% by using the residual temperature to obtain sol gel;
and 4, step 4: drying the sol-gel obtained in the step (3) in a drying oven at 70 ℃ for 24 hours to obtain dry gel;
and 5: and (4) putting the xerogel prepared in the step (4) into a quartz tube for self-combustion-annealing treatment, heating the furnace to 280 ℃ under an inert atmosphere, closing inert gas, then pushing the sample into a temperature zone until no bubbles emerge from the tail end of a gas outlet, heating to 520 ℃, preserving the temperature for 60min, stopping heating, introducing the inert gas for auxiliary cooling, and collecting the sample when the temperature is reduced to room temperature, thereby obtaining the silicon/carbon composite cathode material.
Example 3
The preparation method of the silicon/carbon composite anode material comprises the following steps:
step 1: according to the mol ratio of 1: 3, accurately weighing ferric chloride and citric acid, adding the ferric chloride into a 500ml beaker, adding a 200ml deionized water glass rod, stirring until the ferric chloride is completely dissolved, adding the citric acid, and heating to obtain a chelate;
step 2: adding elemental silicon powder into the chelate, wherein the mass ratio of the silicon powder to the citric acid in the step 1 is 4:1, obtaining a mixture;
and step 3: heating and stirring by using a magnetic stirrer with heating, stopping heating when water in the mixture is evaporated to the residual 50 wt% of water, and continuously evaporating the water to the residual 30 wt% of water by using the residual temperature to obtain sol gel;
and 4, step 4: drying the sol-gel obtained in the step 3 in a drying oven at 90 ℃ for 18h to obtain dry gel;
and 5: and (4) putting the xerogel prepared in the step (4) into a quartz tube for self-combustion-annealing treatment, heating the furnace to 220 ℃ under the inert atmosphere, closing the inert gas, then pushing the sample into a temperature zone until no bubble emerges from the tail end of the gas outlet, heating to 480 ℃ and preserving the temperature for 70min, stopping heating, introducing the inert gas for auxiliary cooling, and collecting the sample when the temperature is reduced to room temperature to obtain the silicon/carbon composite cathode material.
Example 4
The preparation method of the silicon/carbon composite anode material comprises the following steps:
step 1: according to the mol ratio of 1: 4 weighing copper fluoride and triethanolamine, adding water, mixing, and heating to obtain a chelate;
step 2: adding silicon into the chelate, wherein the mass ratio of the silicon to the triethanolamine in the step 1 is 2:1, obtaining a mixture;
and step 3: heating and stirring by using a magnetic stirrer with heating, stopping heating when water in the mixture is evaporated to the residual 50 wt% of water, and continuously evaporating the water to the residual 20 wt% of water by using the residual temperature to obtain sol gel;
and 4, step 4: drying the sol-gel obtained in the step 3 in a drying oven at 100 ℃ for 12 hours to obtain dry gel;
and 5: and (4) putting the xerogel prepared in the step (4) into a quartz tube for self-combustion-annealing treatment, heating the furnace to 200 ℃ under an inert atmosphere, closing the inert gas, then pushing the sample into a temperature zone until no bubbles emerge from the tail end of the gas outlet, heating to 550 ℃, keeping the temperature for 40min, stopping heating, introducing the inert gas for auxiliary cooling, and collecting the sample when the temperature is reduced to room temperature, thereby obtaining the silicon/carbon composite cathode material.
Example 5
The preparation method of the silicon/carbon composite anode material comprises the following steps:
step 1: according to the mol ratio of 1:1, accurately weighing ferric nitrate and ethylene diamine tetraacetic acid, adding water, mixing, and heating to obtain a chelate;
step 2: adding silicon powder into the chelate, wherein the mass ratio of the silicon powder to the ethylenediamine tetraacetic acid in the step 1 is 5:1, obtaining a mixture;
and step 3: heating and stirring by using a magnetic stirrer with heating, stopping heating when water in the mixture is evaporated to the residual 40 wt% of water, and continuously evaporating the water to 20 wt% of water by using the residual temperature to obtain sol gel;
and 4, step 4: drying the sol-gel obtained in the step (3) in a drying oven at 60 ℃ for 48 hours to obtain dry gel;
and 5: and (4) putting the xerogel prepared in the step (4) into a quartz tube for self-combustion-annealing treatment, heating the furnace to 300 ℃ under an inert atmosphere, closing the inert gas, then pushing the sample into a temperature zone until no bubbles emerge from the tail end of the gas outlet, heating to 450 ℃, keeping the temperature for 80min, stopping heating, introducing the inert gas for auxiliary cooling, and collecting the sample when the temperature is reduced to room temperature, thereby obtaining the silicon/carbon composite cathode material.
Comparative example 1
A comparative composite was prepared by the following steps:
①, putting the silicon powder and the EDTA into a beaker according to the mass ratio of 7: 2, adding 200ml of deionized water into the beaker, heating to dissolve the EDTA, adding the Si material into the solution, stirring while heating by using a magnetic stirrer with heating, stopping heating when water is evaporated to of the remaining half, and continuously evaporating the water to of the third by using the remaining temperature to obtain a slurry;
② the slurry obtained in ① was dried in a drying cabinet at 80 ℃ for 30h to obtain a solid mixture of Si/EDTA
③ placing the ② prepared Si/EDTA solid mixture into a quartz tube, heating the furnace to 300 ℃ under an inert atmosphere, closing inert gas, pushing the sample into a temperature zone until no bubble emerges from the tail end of an air outlet, heating to 500 ℃, keeping the temperature for 60min, stopping heating, introducing inert gas for auxiliary cooling, and collecting the sample when the temperature is reduced to room temperature, thereby obtaining the comparative composite material 1.
Comparative example 2
①, putting silicon oxide powder and cobalt nitrate hexahydrate into a beaker according to the mass ratio of 14: 3, adding 200ml of deionized water, stirring to dissolve the cobalt nitrate hexahydrate, adding a Si material into the solution, stirring while heating by using a magnetic stirrer with heating, stopping heating when water is evaporated to the remaining half , and continuously evaporating the water to the third by using the remaining temperature to obtain slurry;
② drying the slurry obtained in ① at 80 deg.C for 30h to obtain Si/Co+Solid mixture
③ Si/Co from ②+And (3) putting the solid mixture into a quartz tube, heating the furnace to 300 ℃ under an inert atmosphere, closing inert gas, pushing the sample into a temperature zone until no bubble appears at the tail end of a gas outlet, heating to 500 ℃, keeping the temperature for 60min, stopping heating, introducing the inert gas for assisting in cooling, and collecting the sample when the temperature is reduced to room temperature, thereby obtaining the comparative composite material 2.
Electrochemical performance
Taking the silicon/carbon composite negative electrode material prepared in the example 1, the comparative composite material 1 prepared in the comparative example 1 and the comparative composite material 2 prepared in the comparative example 2 as negative electrode materials, mixing the negative electrode materials, the binder PAA (acrylic resin) and the conductive agent graphite according to the mass ratio of 70:15:15 and using deionized water as a solvent, obtaining slurry by using mechanical stirring, and then sieving and defoaming the slurry. Coating the slurry on a current collector copper foil, drying for 12h at 100 ℃ in vacuum, rolling and punching to obtain a negative plate with the diameter of 15 mm.
The battery is assembled in a glove box filled with argon gas for operation, the assembly sequence is sequentially a positive electrode shell, a negative electrode sheet, a diaphragm, electrolyte, a lithium sheet, a gasket, a spring sheet and a negative electrode shell, and the electrolyte is 1mol/L LiPF (fluorinated ethylene carbonate) added with 10% (volume fraction) FEC (fluorinated ethylene carbonate)6DMC (volume ratio of 1:1), and the diaphragm is a polypropylene microporous membrane.
When a battery is tested, the charging and discharging curves of the silicon/carbon composite negative electrode material prepared in the embodiment 1 under different cycle times are shown in fig. 4, and as can be seen from the graph 4, the novel silicon/carbon composite negative electrode material prepared in the embodiment 1 has a stable charging and discharging platform, the first coulombic efficiency of the material prepared in the invention is 74.9% due to lithium intercalation for the first time, while the second coulombic efficiency is 96.3%, the 5 th coulombic efficiency is 98.5%, and the 10 th coulombic efficiency is 98.3%, and the material prepared in the invention can form a stable SEI film, so that the material has good electrochemical stability.
The cycle performance curve of each battery is shown in fig. 5, and it can be seen that the novel silicon/carbon composite negative electrode material prepared in example 1 of the present invention shows high capacity and good cycle stability, the material prepared in comparative example 1 has good stability but poorer capacity than example 1, and the material prepared in comparative example 2 has the worst capacity and stability than example 1 and comparative example 1, which indicates that in example 1, a silicon material and a chelate compound are mixed to form a xerogel, and then the subsequent self-combustion and annealing treatment are performed, so that structural pulverization caused by volume expansion of the silicon material is effectively alleviated, and Li + is effectively prevented from being consumed by excessive SEI film formed by volume expansion of the silicon material in the process of lithium ion deintercalation, thereby ensuring the capacity and stability of the material.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (10)
- The preparation method of the silicon/carbon composite anode materials is characterized by comprising the following steps:step 1: mixing a chelating agent, a transition metal salt and water, heating and stirring to obtain a chelate;step 2: adding a silicon material into the chelate obtained in the step 1 to obtain a mixture;and step 3: heating the mixture obtained in the step 2 while stirring to evaporate water to obtain sol-gel;and 4, step 4: drying the sol gel prepared in the step 3 to obtain dry gel;and 5: and (4) burning the xerogel obtained in the step (4) in an inert atmosphere, and annealing to obtain the silicon/carbon composite cathode material.
- 2. The method for preparing a silicon/carbon composite anode material according to claim 1, characterized in that: the molar ratio of the chelating agent to the transition metal salt in the step 1 is 1:1-4: 1;optionally, the chelating agent is any of oxalic acid, acetic acid, citric acid, lauric acid, tartaric acid, gluconic acid, ethylenediamine tetraacetic acid, triethanolamine and ethylenediamine;optionally, the transition metal salt is selected from any kinds of iron salt, ferrous salt, cobalt salt, manganese salt, nickel salt and copper salt;optionally, the transition metal salt is kinds of iron nitrate, ferric sulfate, ferric chloride, ferrous nitrate, ferrous sulfate, ferrous chloride, cobalt nitrate, cobalt acetate, cobalt oxalate, cobalt sulfate, cobalt chloride, manganese chloride, nickel nitrate, nickel sulfate, nickel chloride, copper sulfate, copper chloride, copper nitrate and copper fluoride;optionally, the mass ratio of the silicon material in the step 2 to the chelating agent in the step 1 is 2:1-5: 1;optionally, the silicon material in step 2 is silicon or silicon oxide.
- 3. The method for preparing a silicon/carbon composite anode material according to claim 1, characterized in that: the step 3 comprises the following steps: 3a) heating the mixture obtained in the step 2 while stirring, stopping heating when the water is evaporated to the residual water of 40-50 wt%, and 3b) continuously evaporating the water to the residual water of 20-35 wt% by using the residual temperature to obtain the sol-gel.
- 4. The method for preparing a silicon/carbon composite anode material according to claim 1, characterized in that: in the step 4, the drying temperature is 60-100 ℃, and the drying time is 12-48 h.
- 5. The method for preparing a silicon/carbon composite anode material according to claim 1, characterized in that: and step 5 comprises 5a) heating the tubular furnace to 200-plus-300 ℃ under an inert atmosphere, closing the inert gas, then pushing the dry gel obtained in step 4 into the tubular furnace, 5b) heating to 450-plus-550 ℃ after no bubble emerges from the tail end of the gas outlet of the tubular furnace, preserving the heat for 40-80min, self-combusting the dry gel, 5c) stopping heating, introducing the inert gas for assisting in cooling, cooling to room temperature, collecting a sample, and crushing to obtain the silicon/carbon composite cathode material.
- 6, kinds of silicon/carbon composite negative electrode material, which is prepared by the preparation method of the silicon/carbon composite negative electrode material of any of claims 1-5.
- 7. The silicon/carbon composite anode material according to claim 6, characterized in that: the average pore diameter of the silicon/carbon composite negative electrode material is 2-8 microns, and the porosity is 30-96%.
- 8, kinds of negative active materials, characterized in that the negative active material contains the silicon/carbon composite negative electrode material according to claim 6 or 7.
- 9, negative plate of Li-ion battery, comprising negative current collector and active material distributed on the current collector, wherein the active material contains the negative active material of claim 8.
- 10, lithium ion battery, which comprises a positive plate, a negative plate, a separation film between the positive plate and the negative plate, and electrolyte, wherein the negative plate is the lithium ion battery negative plate of claim 9.
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| CN113594434A (en) * | 2021-07-21 | 2021-11-02 | 昆明理工大学 | Preparation method of dandelion-shaped core-shell structure silicon-ferrous oxalate lithium ion battery material |
| CN115911321A (en) * | 2022-11-22 | 2023-04-04 | 中南大学 | Diatom-based composite material and preparation method and application thereof |
| WO2023202189A1 (en) * | 2022-04-22 | 2023-10-26 | 贝特瑞新材料集团股份有限公司 | Negative electrode material and preparation method therefor, and lithium-ion battery |
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