CN113461015B - Preparation method of nitrogen-doped carbon-coated porous silicon - Google Patents

Preparation method of nitrogen-doped carbon-coated porous silicon Download PDF

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CN113461015B
CN113461015B CN202110750168.4A CN202110750168A CN113461015B CN 113461015 B CN113461015 B CN 113461015B CN 202110750168 A CN202110750168 A CN 202110750168A CN 113461015 B CN113461015 B CN 113461015B
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nitrogen
porous silicon
doped carbon
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CN113461015A (en
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冯金奎
安永灵
田园
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Shandong University
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    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The present disclosure relates to the technical field of porous silicon preparation, and in particular relates to a preparation method of nitrogen-doped carbon-coated porous silicon, which comprises: mixing silicon-magnesium alloy serving as a precursor with carbon nitride, performing first heat treatment under an inert atmosphere or vacuum condition, then continuously heating, and performing second heat treatment under the inert atmosphere or vacuum condition; or, mixing the silicon-magnesium alloy serving as a precursor with carbon nitride, performing heat treatment under inert atmosphere or vacuum condition, then treating the intermediate product in acid, and drying to obtain the nitrogen-doped carbon-coated porous silicon. The method can effectively improve the binding force between the carbon coating layer and silicon and improve the electrochemical stability of the porous silicon anode material.

Description

Preparation method of nitrogen-doped carbon-coated porous silicon
Technical Field
The present disclosure relates to the technical field of porous silicon preparation, and in particular relates to a preparation method of nitrogen-doped carbon-coated porous silicon.
Background
The disclosure of this background section is only intended to increase the understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art already known to those of ordinary skill in the art.
When silicon is used as a negative electrode material of a lithium ion battery, the silicon has the advantages of ultrahigh theoretical specific capacity, lower lithium intercalation and deintercalation potential, environment friendliness, rich reserves and the like, and is considered to be very hopeful to replace the traditional graphite negative electrode material to be used as a negative electrode material of a next-generation high-energy-density lithium ion battery. However, silicon anodes undergo large volume changes during repeated delithiation, which is believed to be a major cause of insufficient cycle life. Its short cycle life prevents commercial application of silicon anodes. In addition, the silicon anode has a problem of poor electron conductivity, so that it has poor rate performance.
The special silicon material structure is designed to better solve the problems of the silicon cathode. In many structures, porous silicon can effectively buffer volume change in the cyclic process, increase interface contact and accelerate ion transmission, and better electrochemical performance is obtained. In addition, the carbon coating layer can also inhibit the volume change in the lithium intercalation and deintercalation process and improve the electronic conductivity of the silicon material, and can further improve the electrochemical performance of the silicon anode.
However, the inventors found that the conventional method for preparing the carbon coating layer is complicated in process, and the bonding force between the carbon coating layer and silicon is poor, which easily causes the carbon coating layer to be detached during the electrochemical cycling reaction. For example, the prior patent discloses that silicide and a carbon source are mixed for heat treatment and acid washing to obtain a porous silicon/carbon composite material, but the process needs acid washing, and the use of acid not only causes environmental pollution, but also is easy to etch a pore structure to cause structural collapse; jeong et al uses ethylenediamine as a nitrogen-doped carbon source to coat porous silicon, but the method directly mixes ethylenediamine with porous silicon, reflows, and carries out heat treatment, so that the carbon coating layer and the silicon cannot be produced simultaneously, and the bonding force between the carbon coating layer and the silicon is weak; shi et al used gelatin as the nitrogen-doped carbon source, but this method required calcium carbonate, acid washing, etc., increased the preparation complexity and brought about acid contamination problems, and it was also difficult to improve the bonding force between the carbon coating and silicon.
Therefore, developing a method for preparing nitrogen-doped carbon-coated porous silicon which is green, low in cost and capable of improving the bonding force between the carbon coating layer and silicon is of great significance in accelerating commercialization of silicon.
Disclosure of Invention
Research finds that the current method for preparing the carbon-coated porous silicon has serious acid pollution, complex preparation process and difficult problem of weak binding force between the carbon coating layer and silicon, and in order to solve the problem, the present disclosure provides a preparation method of nitrogen-doped carbon-coated porous silicon.
Specifically, the technical scheme of the present disclosure is as follows:
in a first aspect of the present disclosure, a method for preparing nitrogen-doped carbon-coated porous silicon includes: mixing silicon-magnesium alloy serving as a precursor with carbon nitride, performing heat treatment under inert atmosphere or vacuum condition, then treating an intermediate product in acid, and drying;
or mixing the silicon-magnesium alloy serving as a precursor with carbon nitride, performing first heat treatment under an inert atmosphere or vacuum condition, then continuously heating, and performing second heat treatment under the inert atmosphere or vacuum condition to obtain the nitrogen-doped carbon-coated porous silicon.
In a second aspect of the present disclosure, the nitrogen-doped carbon-coated porous silicon material obtained by the above-described method for producing a nitrogen-doped carbon-coated porous silicon.
In a third aspect of the disclosure, a lithium ion battery includes a negative electrode material, an electrolyte, and a positive electrode material, where the negative electrode material is the nitrogen doped carbon coated porous silicon material described above.
In a fourth aspect of the disclosure, the nitrogen-doped carbon-coated porous silicon material and/or the lithium ion battery are used in the fields of energy storage devices and electric vehicles.
One or more of the technical schemes in the disclosure have the following beneficial effects:
(1) And adopting the silicon-magnesium alloy as a precursor, mixing and pyrolyzing the silicon-magnesium alloy with carbon nitride, and reacting magnesium in the precursor alloy with the carbon nitride in the pyrolysis process to generate magnesium nitride and nitrogen-doped carbon, so as to form a nitrogen-doped carbon coating layer, and greatly improve the bonding force between the carbon coating layer and silicon. In addition, the nitrogen doped carbon coated porous silicon can be obtained by evaporating magnesium nitride at a higher temperature.
(2) According to research, in the process of simultaneously pyrolyzing the silicon-magnesium alloy and the carbon nitride, a two-stage calcination method is adopted, and the carbon nitride is matched with the two-stage calcination, so that the binding force between the carbon coating layer and the silicon can be improved, acid washing can be avoided, and the electrochemical performance of the porous silicon is greatly improved.
(3) In the preparation method, the carbon coating layer with controllable graphitization degree can be prepared by adjusting the synthesis temperature, and the generation of the nitrogen-doped carbon coating layer and the generation of silicon are performed simultaneously, so that the bonding force between the silicon and the coating layer is stronger, which is beneficial to improving the electronic conductivity and buffering the volume change, and the improved electrochemical performance is obtained.
(4) The step of acid washing can be avoided by evaporating the intermediate product, and silicon with a porous structure can be obtained, so that the volume change in the buffer circulation process is facilitated, the transmission of ions and the infiltration of electrolyte are promoted, and good electrochemical performance is obtained.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate and explain the exemplary embodiments of the disclosure and together with the description serve to explain the disclosure, and do not constitute an undue limitation on the disclosure.
Fig. 1 is an XRD pattern of the precursor magnesium silicide alloy in example 1.
Fig. 2 is an XRD pattern of the nitrogen-doped carbon-coated porous silicon material prepared in example 1.
Fig. 3 is a Raman diagram of the nitrogen-doped carbon-coated porous silicon material prepared in example 1.
Fig. 4 is an SEM image (3500 times) of the nitrogen-doped carbon-coated porous silicon material prepared in example 1.
Fig. 5 is an SEM image (10000 times) of the nitrogen-doped carbon-coated porous silicon material prepared in example 1.
Fig. 6 is an SEM image (20000 x) of the nitrogen-doped carbon-coated porous silicon material prepared in example 1.
Fig. 7 is a cyclic voltammogram of the nitrogen-doped carbon-coated porous silicon material prepared in example 1 as a negative electrode material for a lithium ion battery.
Fig. 8 is a charge-discharge curve of the nitrogen-doped carbon-coated porous silicon material prepared in example 1 as a negative electrode material of a lithium ion battery.
Fig. 9 is a cycle performance of the nitrogen-doped carbon-coated porous silicon material prepared in example 1 as a negative electrode material for a lithium ion battery.
Detailed Description
The disclosure is further illustrated below in conjunction with specific embodiments. It should be understood that these examples are merely illustrative of the present disclosure and are not intended to limit the scope of the present disclosure. The experimental procedures, which do not address the specific conditions in the examples below, are generally carried out under conventional conditions or under conditions recommended by the manufacturer.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The reagents or materials used in the present invention may be purchased in conventional manners, and unless otherwise indicated, they may be used in conventional manners in the art or according to the product specifications. In addition, any methods and materials similar or equivalent to those described herein can be used in the methods of the present invention. The preferred methods and materials described herein are presented for illustrative purposes only.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments in accordance with the present disclosure. As used herein, the singular forms also are intended to include the plural forms unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, and/or combinations thereof.
At present, the process for preparing the silicon negative electrode is complex, acid and other pollution chemical substances are used, and the existing preparation method only utilizes the characteristics of conductivity and the like of the carbon material, and does not consider the binding force between the carbon coating layer and silicon, so that the prepared carbon-coated porous silicon material has poor stability, and the problems of active substance falling off, volume expansion and the like easily occur in the electrochemical circulation process. To this end, the present disclosure provides a method of preparing nitrogen-doped carbon-coated porous silicon.
In one embodiment of the present disclosure, a method for preparing nitrogen-doped carbon-coated porous silicon includes: mixing silicon-magnesium alloy serving as a precursor with carbon nitride, performing heat treatment under inert atmosphere or vacuum condition, then treating an intermediate product in acid, and drying;
or mixing the silicon-magnesium alloy serving as a precursor with carbon nitride, performing first heat treatment under an inert atmosphere or vacuum condition, then continuously heating, and performing second heat treatment under the inert atmosphere or vacuum condition to obtain the nitrogen-doped carbon-coated porous silicon.
Carbon nitride has a graphite-like layered structure, and rings are connected through terminal N atoms to form a layer of infinitely extended planes, so that the carbon nitride has excellent physical and chemical properties. Carbon nitride is rich in nitrogen and provides a sufficient source of nitrogen to obtain nitrogen doped carbon. In the pyrolysis process, the unique structure of the carbon nitride reacts with magnesium to generate magnesium nitride and nitrogen-doped carbon, so that a uniform carbon coating layer can be obtained. With the generation and removal of the intermediate product magnesium nitride, the porous silicon is gradually formed, and the generation of the nitrogen-doped carbon coating layer and the generation of silicon are simultaneously carried out, so that the binding force between the carbon coating layer and the silicon is improved.
The temperature of the first heat treatment is 550-950 ℃ and the time is 0.5-5h under the inert atmosphere; or, the temperature of the second heat treatment is 1100-1300 ℃ under the inert atmosphere, and the time is 0.1-2h.
Or, under vacuum condition, the temperature of the first heat treatment is 500-900 ℃ and the time is 0.5-5h; or, the temperature of the second heat treatment is 1000-1200 ℃ under the vacuum condition, and the time is 0.1-2h.
In the first heat treatment process, the carbon nitride reacts with magnesium in the silicon-magnesium alloy to generate magnesium nitride and nitrogen-doped carbon, and the nitrogen-doped carbon is gradually coated on the surface of the porous silicon. And (3) continuing heating heat treatment, further enhancing the binding force between the carbon coating layer and the silicon, evaporating the intermediate product magnesium nitride, and synthesizing the target product nitrogen-doped carbon-coated porous silicon.
Wherein the inert atmosphere is one or two mixed gases of argon and nitrogen.
The vacuum condition is that the vacuum degree is less than or equal to 10Pa.
In one embodiment of the present disclosure, the acid is one or a mixture of two or more of hydrochloric acid, sulfuric acid, acetic acid, oxalic acid, citric acid, phosphoric acid, sulfurous acid, hydrofluoric acid, formic acid, benzoic acid, acetic acid, propionic acid, stearic acid, carbonic acid, hydrogen sulfuric acid, hypochlorous acid, boric acid, silicic acid. Impurities such as oxides can be removed by acid washing, and more pore structures are exposed.
In one embodiment of the present disclosureThe nitrogen-doped carbon-coated porous silicon material obtained by the preparation method of the nitrogen-doped carbon-coated porous silicon has the carbon content of 5-30 percent and the specific surface area of 50-200m 2 g -1 The pore size distribution is 1-100nm.
In one embodiment of the disclosure, a lithium ion battery comprises a negative electrode material, an electrolyte and lithium metal, wherein the negative electrode material is the nitrogen-doped carbon-coated porous silicon material;
further, the electrolyte in the electrolyte is one or a mixture of more than two of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis (difluoro-sulfonyl imide), lithium bis (trifluoromethyl-sulfonyl imide), lithium difluoro (oxalato) borate and lithium bis (oxalato) borate;
further, the solvent in the electrolyte is one or a mixture of more than two of Ethylene Carbonate (EC), propylene Carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC) and methylpropyl carbonate (MPC);
in one embodiment of the disclosure, the nitrogen-doped carbon-coated porous silicon material and/or the lithium ion battery are used in the fields of energy storage devices and electric vehicles.
In order to enable those skilled in the art to more clearly understand the technical solutions of the present disclosure, the technical solutions of the present disclosure will be described in detail below with reference to specific embodiments.
Example 1
A preparation method of nitrogen-doped carbon-coated porous silicon comprises the steps of taking 1.0g of magnesium silicide and 2.5g of carbon nitride powder, uniformly mixing, placing the mixture in a tube furnace, introducing argon, carrying out heat treatment at 900 ℃ for 0.5h, continuously raising the temperature, carrying out heat treatment at 1100 ℃ for 0.1h, cooling to room temperature, carrying out 2M hydrochloric acid solution treatment for 2h to remove impurities in the product, and filtering, washing and drying to obtain the nitrogen-doped carbon-coated porous silicon material.
And (3) battery assembly:
preparing a negative electrode material: uniformly mixing the nitrogen-doped carbon-coated porous silicon, the carbon black and the PAA according to the mass ratio of 6:2:2, adding deionized water, stirring for 12 hours, coating the mixture on a copper foil, and drying the mixture at 80 ℃ for 15 hours under a vacuum condition to obtain the required anode material.
The electrolyte adopts 1M LiPF 6 /(ec+edc), the battery was assembled in a glove box using a metallic lithium sheet as the counter electrode and working electrode.
Performance test:
cyclic voltammetry test: the sweep rate was 0.2mV s -1 The voltage interval is 0.01V-3V.
And (3) testing the circularity: the current density was 500mA g -1 The voltage interval is 0.01V-3V.
Fig. 1 is an XRD pattern of the precursor magnesium silicide alloy of example 1, wherein the precursor magnesium silicide has fewer impurities and higher purity.
Fig. 2 is an XRD pattern of the nitrogen-doped carbon-coated porous silicon material prepared in example 1, and characteristic peaks of silicon and characteristic peaks of carbon are observed for the product, illustrating successful synthesis of the nitrogen-doped carbon-coated porous silicon.
Fig. 3 is a Raman graph of the nitrogen-doped carbon-coated porous silicon material prepared in example 1, and characteristic peaks of silicon and characteristic peaks of G and D of carbon are observed in the product, indicating that carbon is successfully coated on the surface of silicon. The nitrogen doped carbon layer can effectively improve the electronic conductivity of the material, promote the transmission of ions, relieve the volume change in the circulation process and obtain good electrochemical performance.
Fig. 4, 5 and 6 are SEM images (3500 times) of the nitrogen-doped carbon-coated porous silicon material prepared in example 1 at different times, and the obtained product is a typical three-dimensional porous structure, which is beneficial to promoting infiltration between the electrolyte and the electrode material, accelerating the ion transport speed, relieving volume expansion during circulation, and obtaining excellent electrochemical properties.
Fig. 7 is a cyclic voltammogram of the nitrogen-doped carbon-coated porous silicon material prepared in example 1 as a negative electrode material of a lithium ion battery, showing typical oxidation and reduction peaks of silicon, indicating that the synthesized silicon-based negative electrode has higher purity and no other impurities. In addition, the coincident curves also indicate that the obtained silicon-based negative electrode has good cycle performance.
FIG. 8 is a nitrogen-doped carbon-coated porous silicon material prepared in example 1As the charge-discharge curve of the lithium ion battery cathode material, the silicon cathode has higher specific capacity and high initial cycle coulomb efficiency, and the reversible capacity reaches 2579mAh g -1 The initial coulombic efficiency was 92.3%, and the coincident curves further demonstrated excellent cycling performance of the modified silicon negative electrode.
FIG. 9 is a graph showing the cycle performance of the nitrogen-doped carbon-coated porous silicon material prepared in example 1 as a negative electrode material for a lithium ion battery, and the capacity after 20 weeks of cycle was 2180mAh g -1 And shows good cycle performance. This further demonstrates that the binding force between the nitrogen-doped carbon and the porous silicon is strong, the coating layer does not fall off from the surface of the silicon in the circulation process, the ion transmission and the buffer volume change can be effectively promoted, and excellent electrochemical performance is obtained.
Example 2
A preparation method of nitrogen-doped carbon-coated porous silicon comprises the steps of taking 1.0g of magnesium silicide and 2.5g of carbon nitride powder, uniformly mixing, placing the mixture in a tube furnace, introducing argon, carrying out heat treatment at 800 ℃ for 2 hours, then continuously raising the temperature, continuously raising the temperature to 1300 ℃ under the argon condition for 0.1 hour, cooling to room temperature, then treating with 2M hydrochloric acid solution for 2 hours to remove impurities in the product, filtering, washing and drying to obtain the nitrogen-doped carbon-coated porous silicon material.
Example 3
A preparation method of nitrogen-doped carbon-coated porous silicon comprises the steps of taking 1.0g of magnesium silicide and 2.5g of carbon nitride powder, uniformly mixing, placing the mixture in a tube furnace, carrying out heat treatment at 600 ℃ for 4 hours under vacuum condition, then continuously raising the temperature, continuously raising the temperature to 1300 ℃ under vacuum condition for 0.1 hour, cooling to room temperature, then treating with 2M hydrochloric acid solution for 2 hours to remove impurities in the product, filtering, washing and drying to obtain the nitrogen-doped carbon-coated porous silicon material.
Example 4
A preparation method of nitrogen-doped carbon-coated porous silicon comprises the steps of taking 1.0g of magnesium silicide and 2.5g of carbon nitride powder, uniformly mixing, placing the mixture in a tube furnace, carrying out heat treatment at 700 ℃ for 3 hours under vacuum condition, then continuously raising the temperature, continuously raising the temperature to 1200 ℃ under argon condition for 1.0 hour, cooling to room temperature, then treating with 2M hydrochloric acid solution for 2 hours to remove impurities in the product, filtering, washing and drying to obtain the nitrogen-doped carbon-coated porous silicon material.
Example 5
A preparation method of nitrogen-doped carbon-coated porous silicon comprises the steps of taking 1.0g of magnesium silicide and 2.5g of carbon nitride powder, uniformly mixing, placing the mixture in a tube furnace, carrying out heat treatment at 500 ℃ for 0.5h under vacuum condition, then continuously increasing the temperature, continuously increasing the temperature to 1000 ℃ under vacuum condition for 0.2h, cooling to room temperature, then treating with 2M hydrochloric acid solution for 2h to remove impurities in the product, filtering, washing and drying to obtain the nitrogen-doped carbon-coated porous silicon material.
Example 6
A preparation method of nitrogen-doped carbon-coated porous silicon comprises the steps of taking 1.0g of silicon-aluminum alloy and 2.0g of carbon nitride powder, uniformly mixing, placing the mixture in a tube furnace, introducing argon, carrying out heat treatment at 910 ℃ for 1.5 hours, then continuously raising the temperature, continuously raising the temperature to 1100 ℃ under vacuum condition for 0.5 hour, cooling to room temperature, then treating with 2M hydrochloric acid solution for 2 hours to remove impurities in the product, filtering, washing and drying to obtain the nitrogen-doped carbon-coated porous silicon material.
Example 7
A preparation method of nitrogen-doped carbon-coated porous silicon comprises the steps of taking 1.5g of silicon-zinc alloy and 2.5g of carbon nitride powder, uniformly mixing, placing the mixture in a tubular furnace, carrying out heat treatment at 600 ℃ for 2.5h under vacuum condition, then continuously raising the temperature, continuously raising the temperature to 1200 ℃ under vacuum condition for 2h, cooling to room temperature, then treating with 2M hydrochloric acid solution for 2h to remove impurities in the product, filtering, washing and drying to obtain the nitrogen-doped carbon-coated porous silicon material.
Example 8
A preparation method of nitrogen-doped carbon-coated porous silicon comprises the steps of taking 1.5g of silicon-antimony alloy and 3.0g of carbon nitride powder, uniformly mixing, placing the mixture in a tubular furnace, carrying out heat treatment at 800 ℃ for 3 hours under vacuum condition, then continuously raising the temperature, continuously raising the temperature to 1200 ℃ under argon condition for 1.0 hour, cooling to room temperature, then treating with 2M hydrochloric acid solution for 2 hours to remove impurities in the product, filtering, washing and drying to obtain the nitrogen-doped carbon-coated porous silicon material.
Example 9
A preparation method of nitrogen-doped carbon-coated porous silicon comprises the steps of taking 0.8g of silicon-magnesium alloy and 2.0g of carbon nitride powder, uniformly mixing, placing the mixture in a tube furnace, introducing argon, carrying out heat treatment at 750 ℃ for 2h, cooling to room temperature, treating with 2M hydrochloric acid solution for 20h, filtering, washing and drying to obtain the nitrogen-doped carbon-coated porous silicon material.
Example 10
A preparation method of nitrogen-doped carbon-coated porous silicon comprises the steps of taking 0.8g of silicon-aluminum alloy and 2.0g of carbon nitride powder, uniformly mixing, placing the mixture in a tube furnace, introducing argon, carrying out heat treatment at 900 ℃ for 0.5h, cooling to room temperature, treating with 1M sulfuric acid solution for 25h, filtering, washing and drying to obtain the nitrogen-doped carbon-coated porous silicon material.
The foregoing description is only a preferred embodiment of the present invention, and the present invention is not limited thereto, but it is to be understood that modifications and equivalents of some of the technical features described in the foregoing embodiments may be made by those skilled in the art, although the present invention has been described in detail with reference to the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (5)

1. The preparation method of the nitrogen-doped carbon-coated porous silicon is characterized by comprising the following steps of: mixing silicon-magnesium alloy serving as a precursor with carbon nitride, performing heat treatment under inert atmosphere or vacuum condition, then treating an intermediate product in acid, and drying;
or, mixing the silicon-magnesium alloy serving as a precursor with carbon nitride, performing first heat treatment under an inert atmosphere or vacuum condition, then continuously heating, and performing second heat treatment under the inert atmosphere or vacuum condition to obtain the nitrogen-doped carbon-coated porous silicon;
the temperature of the first heat treatment is 550-950 ℃ and the time is 0.5-5h under inert atmosphere; the temperature of the second heat treatment is 1100-1300 ℃ and the time is 0.1-2h under the inert atmosphere;
under vacuum condition, the temperature of the first heat treatment is 500-900 ℃ and the time is 0.5-5h; under vacuum condition, the temperature of the second heat treatment is 1000-1200 ℃ and the time is 0.1-2h;
the silicon magnesium alloy is magnesium silicide alloy.
2. The method for preparing nitrogen-doped carbon-coated porous silicon according to claim 1, wherein the acid is one or more of hydrochloric acid, sulfuric acid, acetic acid, oxalic acid, citric acid, phosphoric acid, sulfurous acid, hydrofluoric acid, formic acid, benzoic acid, acetic acid, propionic acid, stearic acid, carbonic acid, hydrogen sulfate, hypochlorous acid, boric acid, and silicic acid.
3. The nitrogen-doped carbon-coated porous silicon material obtained by the method for producing a nitrogen-doped carbon-coated porous silicon of any one of claims 1 to 2.
4. A lithium ion battery, comprising a negative electrode material, an electrolyte and a positive electrode material, wherein the negative electrode material is the nitrogen-doped carbon-coated porous silicon material of claim 3; further, the electrolyte in the electrolyte is one or a mixture of more than two of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis (difluoro-sulfonyl imide), lithium bis (trifluoromethyl-sulfonyl imide), lithium difluoro (oxalato) borate and lithium bis (oxalato) borate; the solvent in the electrolyte is one or more than two of Ethylene Carbonate (EC), propylene Carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC) and Methyl Propyl Carbonate (MPC); the positive electrode material is selected from lithium manganate, lithium cobaltate, lithium iron phosphate, lithium nickel cobalt manganate or lithium nickelate.
5. Use of the nitrogen-doped carbon-coated porous silicon material of claim 3 and/or the lithium ion battery of claim 4 in the fields of energy storage devices, electric vehicles.
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CN108110240A (en) * 2017-12-15 2018-06-01 山东大学 A kind of nano-structure porous silicon base complex electrode material and preparation method thereof
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