CN114824200A - Hierarchical carbon-coated silicon micro-nano composite anode material and preparation method and application thereof - Google Patents
Hierarchical carbon-coated silicon micro-nano composite anode material and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses a hierarchical carbon-coated silicon micro-nano composite anode material as well as a preparation method and application thereof, wherein the preparation method comprises the following steps: dispersing nano-silicon in a solvent, coating phenolic resin or polydopamine in situ to obtain precursor powder, mixing the precursor powder with cyanamide micromolecules and iron transition metal salt, and carrying out high-temperature carbonization treatment to obtain the hierarchical carbon-coated silicon micro-nano composite negative electrode material. The hierarchical carbon-coated silicon micro-nano composite anode material has double carbon coating: the first is that the surface of the nano silicon particles is uniformly coated with a carbon layer, the second is that the surface of an aggregate formed by the carbon-coated silicon nano particles is uniformly coated with a layer of nitrogen-doped lamellar carbon film, and carbon nano tubes grow in situ among the carbon-coated silicon nano particles. The hierarchical carbon-coated silicon micro-nano structure improves the structure and interface stability of a silicon cathode material on one hand, improves the conductivity of a silicon cathode on the other hand, and obviously improves the cycle stability and rate capability of silicon when used as a lithium ion battery cathode material.
Description
Technical Field
The invention relates to the technical field of cathode materials, in particular to a hierarchical carbon-coated silicon micro-nano composite cathode material and a preparation method and application thereof.
Background
Silicon as the negative electrode material of the lithium ion battery has the highest theoretical specific capacity of 4200mAh/g, and the silicon has lower lithium intercalation potential and rich reserve capacity, so the silicon is considered as one of the most ideal negative electrode materials of the next generation of lithium ion batteries. But the intrinsic electronic conductivity of silicon is extremely low, and the electrochemical activity is poor. And the volume expansion of the silicon embedded with lithium can reach 300%, and the huge volume expansion can generate larger stress, so that the silicon negative electrode material is pulverized, and the active material is easy to separate from the current collector, so that the capacity is quickly attenuated. In addition, the volume expansion effect of the silicon negative electrode also causes that a stable solid electrolyte interface (SEI film) is difficult to form on the surface of the silicon negative electrode, so that a fresh SEI film is continuously formed on the surface of the silicon negative electrode, and the specific capacity, the stability, the coulombic efficiency and the like of the silicon negative electrode are seriously influenced.
Researches show that nanocrystallization and carbon coating modification are effective ways for improving the electrochemical performance of silicon materials. However, the pure nanocrystallization modification improves the electrochemical activity of the silicon negative electrode, and simultaneously causes the defects that the tap density of the silicon negative electrode is reduced, and the cycle performance is reduced due to the fact that the nano silicon and the electrolyte easily form an unstable SEI film. The pure carbon-coated silicon technology is beneficial to improving the conductivity of the silicon cathode, but the contact between active materials is point contact, an effective electronic conductive network is difficult to form, and the mechanical strength and the flexibility are not enough, so that the improvement of the cycle performance and the rate capability of the silicon cathode is not facilitated.
Disclosure of Invention
The invention provides a hierarchical carbon-coated silicon micro-nano composite anode material, and a preparation method and application thereof, which are used for overcoming the defects of poor cycle performance and rate capability and the like in the prior art.
In order to achieve the aim, the invention provides a preparation method of a hierarchical carbon-coated silicon micro-nano composite anode material, which comprises the following steps:
s1: adding nano silicon powder into a mixed solution containing a surfactant, stirring, performing ultrasonic treatment, sequentially adding resorcinol and formaldehyde solution, heating, stirring, filtering, washing and drying to obtain precursor powder of phenolic aldehyde coated silicon; the mixed solution consists of water, alcohol and ammonia water;
or adding the nano silicon powder into tris HCl buffer solution containing dopamine hydrochloride, stirring, performing ultrasonic treatment, performing heating reaction, filtering, washing and drying to obtain precursor powder of the poly-dopamine-coated nano silicon;
s2: and mixing the precursor powder with cyanamide micromolecules and iron transition metal salt, ball-milling or uniformly grinding, placing in an inert atmosphere, and performing heat treatment to obtain the hierarchical carbon-coated silicon micro-nano composite negative electrode material.
In order to achieve the purpose, the invention also provides a hierarchical carbon-coated silicon micro-nano composite anode material which is prepared by the preparation method; the composite cathode material comprises a nano silicon-carbon aggregate, wherein the nano silicon-carbon aggregate is a polymer formed by coating a carbon layer on the surface of a nano silicon particle; the carbon nano tube grows in situ in the nano silicon-carbon aggregate, and the surface of the nano silicon-carbon aggregate is uniformly coated by nitrogen-doped lamellar carbon.
In order to achieve the purpose, the invention also provides an application of the hierarchical carbon-coated silicon micro-nano composite negative electrode material, and the composite negative electrode material prepared by the preparation method or the composite negative electrode material is applied to a lithium ion battery.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the preparation method of the hierarchical carbon-coated silicon micro-nano composite negative electrode material, the phenolic resin or polydopamine-coated nano silicon is prepared by taking resorcinol, formaldehyde, dopamine and the like as raw materials, and the raw materials are cheap and easy to obtain; and then grinding or ball-milling and mixing the precursor powder with cyanamide micromolecules, iron transition metal salts and the like, placing the mixture in an inert atmosphere for heat treatment, carbonizing phenolic resin or polydopamine on the surface of the nano silicon to form a first heavy carbon coating layer at high temperature, melting the cyanamide micromolecules at high temperature and coating the molten cyanamide micromolecules on the surface of the silicon carbon precursor powder, forming a second heavy nitrogen-doped lamellar carbon film coating layer on the surface of a nano silicon carbon aggregate formed by carbon-coated silicon after carbonization, and simultaneously growing the carbon nano tubes in situ by the cyanamide micromolecules under the catalysis of the iron transition metal salts to obtain the hierarchical carbon-coated silicon micro-nano composite anode material. The preparation method provided by the invention has the advantages of cheap and easily available raw materials, simple preparation process and capability of realizing mass preparation.
2. The hierarchical carbon-coated silicon micro-nano composite anode material provided by the invention has double carbon protection: the first is that the surface of the nano silicon particles is uniformly coated with a carbon layer, the second is that the surface of an aggregate formed by the carbon-coated silicon nano particles is uniformly coated with a nitrogen-doped lamellar carbon film, and carbon nano tubes grow in situ among the carbon-coated silicon nano particles. The hierarchical carbon-coated silicon micro-nano composite negative electrode material not only maintains the high activity of nano silicon, but also has good structural stability and high tap density of micron particles, and meanwhile, the hierarchical carbon-coated silicon micro-nano structure can more effectively inhibit structural damage and SEI (solid electrolyte interphase) film damage caused by the volume expansion effect of a silicon negative electrode, and can effectively improve electrochemical activity, rate capability and cycling stability when being used as a negative electrode material of a lithium ion battery.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a Scanning Electron Microscope (SEM) image of a hierarchical carbon-coated silicon micro-nano composite anode material in example 1 of the present invention;
FIG. 2 is a cycle performance curve diagram of a lithium ion battery assembled by a hierarchical carbon-coated silicon micro-nano composite anode material in embodiment 1 of the invention;
fig. 3 is a rate performance curve diagram of a lithium ion battery assembled by a hierarchical carbon-coated silicon micro-nano composite anode material in embodiment 1 of the invention;
fig. 4 is a graph showing cycle characteristics of composite anode materials prepared in example 1 of the present invention and comparative example 1.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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.
In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
The drugs/reagents used are all commercially available without specific mention.
The invention provides a preparation method of a hierarchical carbon-coated silicon micro-nano composite anode material, which is characterized by comprising the following steps of:
s1: adding nano silicon powder into a mixed solution containing a surfactant, stirring, performing ultrasonic treatment, sequentially adding resorcinol and formaldehyde solution, heating, stirring, filtering, washing and drying to obtain precursor powder of phenolic aldehyde coated silicon; the mixed solution is composed of water, alcohol and ammonia water.
The surfactant is added to disperse the nano-silicon more uniformly, so that the phenolic resin is coated more uniformly.
The mixed solution consists of water, alcohol and ammonia water, and the resorcinol and the formaldehyde can react to generate the phenolic resin in the environment and slowly and uniformly coat the surface of the nanometer silicon.
Or adding the nano silicon powder into tris HCl buffer solution containing dopamine hydrochloride, stirring, performing ultrasonic treatment, performing heating reaction, filtering, washing and drying to obtain precursor powder of the poly-dopamine-coated nano silicon.
Tris HCl buffer, Tris buffer (Tris-buffer).
S2: and mixing the precursor powder with cyanamide micromolecules and iron transition metal salt, ball-milling or uniformly grinding, placing in an inert atmosphere, and performing heat treatment to obtain the hierarchical carbon-coated silicon micro-nano composite negative electrode material.
The hierarchical carbon-coated silicon micro-nano composite anode material prepared by the invention has double carbon coating: the first is that the surface of the nano silicon particles is uniformly coated with a carbon layer, the second is that the surface of an aggregate formed by the carbon-coated silicon nano particles is uniformly coated with a layer of nitrogen-doped lamellar carbon film, and carbon nano tubes grow in situ among the carbon-coated silicon nano particles. The hierarchical carbon-coated silicon micro-nano structure improves the structure and interface stability of a silicon cathode material on one hand, improves the conductivity of a silicon cathode on the other hand, obviously improves the cycle stability and rate capability of silicon when used as a lithium ion battery cathode material, and has the advantages of simple and convenient preparation method, easy batch preparation, good effect and wide application prospect in lithium ion batteries.
Preferably, in the step S1, the molar ratio of the resorcinol to the formaldehyde is 1 (1-2), and the reaction is more uniform under the condition of the ratio; the mass ratio of the nano silicon powder to the resorcinol is (0.2-20): 1, which is beneficial to forming a carbon coating layer with a certain thickness on the surface of the nano silicon; the ratio of the nano silicon powder to the mixed solution is (0.01-0.5) g:100ml, so that the nano silicon powder is fully and uniformly dispersed in the solution; the mass ratio of the surfactant to the mixed solution is (0.1-2): 100, and the addition of a proper amount of surfactant is beneficial to uniform dispersion of the nano silicon powder in the solution; the volume ratio of the alcohol to the water in the mixed solution is (50-1): 1, and the volume ratio of the ammonia water to the water is 1: (1-20). The appropriate proportion of the solvent and the reaction raw materials is favorable for controlling the reaction rate to uniformly coat the phenolic resin on the surface of the nano silicon.
Preferably, in step S1, the surfactant is at least one of dodecyltrimethyl ammonium chloride, dodecyltrimethyl ammonium bromide, hexadecyltrimethyl ammonium chloride, hexadecyltrimethyl ammonium bromide, and polyvinylpyrrolidone.
Preferably, in step S1, the mass ratio of the nano silicon powder to the dopamine hydrochloride is 100 (5-50), and a proper proportion of reaction raw materials is favorable for uniformly forming a polydopamine coating layer with a certain thickness on the surface of the nano silicon; the concentration of the tris HCl buffer solution is 5-20 mmol/L, and the pH value of the tris HCl buffer solution is 8-9. And selecting a proper buffer, controlling the concentration of the buffer and the pH value of the mixed solution to promote the polymerization reaction of the dopamine hydrochloride to generate the polydopamine polymer.
Preferably, in step S1, the heating and stirring temperature is 20 to 80 ℃ and the time is 12 to 36 hours when the phenolic resin is coated with the nano silicon powder, which is beneficial to controlling the reaction rate of the phenolic resin and realizing uniform coating;
when the poly-dopamine is coated by the nano silicon powder, the heating reaction temperature is 10-60 ℃ and the heating reaction time is 12-24 h, and the appropriate reaction temperature and reaction time are favorable for controlling the reaction rate to uniformly coat the poly-dopamine on the surface of the nano silicon.
Preferably, in step S2, the molar ratio of the iron-based transition metal salt to the cyanamide small molecule is 1 (10 to 100); the mass ratio of the precursor powder to the cyanamide micromolecules is 1 (2-30). And a proper amount of nitrogen-doped lamellar carbon coating layers and carbon nanotube networks can be formed by selecting proper reactant proportion.
Preferably, in step S1, the nano silicon powder has a particle size of 30 to 300nm, and the negative electrode material has more excellent electrochemical performance at the particle size.
Preferably, in step S2, the iron-based transition metal salt is at least one of cobalt nitrate, cobalt chloride, cobalt acetate, cobalt sulfate, iron nitrate, iron chloride, iron acetate, iron sulfate, nickel nitrate, nickel chloride, nickel acetate, and nickel sulfate; the cyanamide micromolecules are at least one of cyanamide, dicyandiamide and melamine. The selected iron transition metal salt can form nano iron transition metal in the subsequent high-temperature heat treatment process so as to catalyze cyanamide micromolecules to form nitrogen-doped carbon nano-sheets or carbon nano-tubes in situ.
Preferably, in step S2, the temperature of the heat treatment is 500-1000 ℃, the temperature rise rate is 1-5 ℃/min, and the time is 0.5-5 h, so that the phenolic resin (polydopamine) is carbonized and cracked to be completely coated on the surface of the nano-silicon particles, and the cyanamide micromolecules are melted, cracked and carbonized to form the nitrogen-doped lamellar carbon coating layer on the surface of the nano-silicon carbon aggregate.
Preferably, the inert atmosphere is Ar gas or N 2 Gas, Ar/H 2 At least one of the mixed gas of (a); the phenolic resin (polydopamine) and cyanamide micromolecules are cracked into nitrogen-doped lamellar carbon or carbon nano tubes in an inert atmosphere, and silicon oxidation is prevented.
The invention also provides a hierarchical carbon-coated silicon micro-nano composite anode material which is prepared by the preparation method; the composite cathode material comprises a nano silicon-carbon aggregate, wherein the nano silicon-carbon aggregate is a polymer formed by coating a carbon layer on the surface of a nano silicon particle; the carbon nano tube grows in situ in the nano silicon-carbon aggregate, and the surface of the nano silicon-carbon aggregate is uniformly coated by nitrogen-doped lamellar carbon.
Preferably, the particle size of the nano silicon is 30-500 nm, the particle size of the micron particles formed by the nano silicon-carbon aggregate is 5-50 um, and the diameter of the in-situ grown carbon nano tube is 10-200 nm.
The invention also provides an application of the hierarchical carbon-coated silicon micro-nano composite anode material, and the composite anode material prepared by the preparation method or the composite anode material is applied to a lithium ion battery.
The hierarchical carbon-coated silicon micro-nano composite negative electrode material provided by the invention is used as a lithium ion battery negative electrode, and the mass fraction of silicon in the hierarchical carbon-coated silicon micro-nano composite negative electrode material is 20-85 wt%.
Example 1
The embodiment provides a hierarchical carbon-coated silicon micro-nano composite cathode material, which is formed by coating a nano silicon carbon aggregate on a nitrogen-doped lamellar carbon film, wherein the grain size of the nano silicon carbon is 30-100 nm, the grain size of the nano silicon carbon aggregate is 10-40 mu m, and the diameter of an in-situ grown carbon nanotube is 10-100 nm.
The invention also provides a preparation method of the hierarchical carbon-coated silicon micro-nano composite anode material, which comprises the following steps:
(1) adding 0.50g of nano silicon powder (with the particle size of 20-80 nm) into a mixed solution of 40ml of water containing 0.1g of dodecyl trimethyl ammonium bromide, 360ml of ethanol and 4ml of ammonia water, stirring, ultrasonically dispersing uniformly, then adding 0.6g of resorcinol until the resorcinol is dissolved, finally adding 0.8g of formaldehyde solution, stirring and reacting at 30 ℃ for 24 hours, filtering, washing and drying to obtain precursor powder of the phenolic coated silicon;
(2) and (3) grinding and uniformly mixing 0.15g of precursor powder, 2g of cyanamide and 0.15g of cobalt nitrate, placing the mixture in a high-purity Ar atmosphere, preserving the heat for 2 hours at 900 ℃, and naturally cooling to obtain the black hierarchical carbon-coated silicon micro-nano composite anode material.
As shown in fig. 1, which is an SEM image of the hierarchical carbon-coated silicon micro-nano composite anode material prepared in this embodiment, it can be seen from the SEM image that the hierarchical carbon-coated silicon micro-nano composite anode material prepared in this embodiment is formed by coating a nano silicon carbon aggregate with a nitrogen-doped lamellar carbon film, the nano silicon carbon aggregate is a polymer formed by coating a carbon layer on the surface of a nano silicon particle, a carbon nanotube grows in situ in the nano silicon carbon aggregate, and the surface is uniformly coated with nitrogen-doped lamellar carbon. The particle size of the nano silicon is 30-100 nm, the particle size of the nano silicon carbon aggregate is 10-40 um, and the diameter of the in-situ grown carbon nano tube is 10-100 nm.
The hierarchical carbon-coated silicon micro-nano composite negative electrode material (the silicon content is 55%) prepared in the embodiment can be used as a negative electrode material of a lithium ion battery, and the hierarchical carbon-coated silicon micro-nano composite negative electrode material, superconducting carbon and a binder LA133 are mixed according to a mass ratio of 8: 1: 1 is dispersed in water solution (solid content is 20 percent) and stirred for 12 hours to obtain even silicon cathode slurry,coating the mixture on a copper foil by a wire bar scraper coater, drying and cutting the mixture into pole pieces with the diameter of 12mm, wherein the silicon loading on the pole pieces is 0.5-1.5 mg/cm 2 The pole piece, the lithium cathode and the diaphragm are assembled into a lithium ion battery in a glove box to carry out charge-discharge and cycle performance tests.
Fig. 2, fig. 3, and fig. 4 are a cycle performance diagram and a rate performance diagram of a lithium ion battery assembled by the hierarchical carbon-coated silicon micro-nano composite anode material prepared in this embodiment, and cycle performance diagrams of the composite anode materials prepared in this embodiment and comparative example 1, respectively. As can be seen from FIG. 2, under the rate of 0.1C, the first discharge capacity of the hierarchical carbon-coated silicon micro-nano composite anode material is 3038mAh/g, the second discharge capacity is 1831mAh/g, after 65 cycles, the discharge capacity is 1364.5mAh/g, and the capacity retention rate is 74.5%. As can be seen from fig. 3, under high multiplying power of 0.5C, 1C, 2C, and 4C, the specific discharge capacity of the hierarchical carbon-coated silicon micro-nano composite anode material can reach 1452.4, 1254.4, 1020.3, 959.8, and 697.1mAh/g, respectively. As can be seen from FIG. 4, the discharge capacity of the composite anode material prepared in comparative example 1 at the magnification of 0.1C is 2999.7mAh/g, the capacity is attenuated to 753.3mAh/g after 20 times of circulation, the capacity retention rate is only 25.1%, and the attenuation is 0.7mAh/g after 50 times of circulation. The hierarchical carbon-coated silicon micro-nano composite anode material has the advantages of high discharge capacity, excellent cycle performance and rate capability.
Example 2
The embodiment provides a hierarchical carbon-coated silicon micro-nano composite cathode material, which is formed by coating a nano silicon carbon aggregate on a nitrogen-doped lamellar carbon film, wherein the grain size of the nano silicon carbon is 100-300 nm, the grain size of the nano silicon carbon aggregate is 20-50 mu m, and the diameter of an in-situ grown carbon nano tube is 10-150 nm.
The invention also provides a preparation method of the hierarchical carbon-coated silicon micro-nano composite anode material, which comprises the following steps:
(1) adding 0.50g of nano silicon powder (with the particle size of 80-280 nm) into a mixed solution of 80ml of water containing 0.02g of dodecyl trimethyl ammonium bromide, 320ml of ethanol and 4ml of ammonia water, stirring, ultrasonically dispersing uniformly, then adding 0.6g of resorcinol until the resorcinol is dissolved, finally adding 0.8g of formaldehyde solution, stirring and reacting at 50 ℃ for 24 hours, filtering, washing and drying to obtain precursor powder of the phenolic coated silicon;
(2) and (3) grinding and uniformly mixing 0.15g of precursor powder, 2g of dicyandiamide and 0.10g of cobalt nitrate, placing the mixture in a high-purity Ar atmosphere, preserving the heat for 2 hours at 800 ℃, and naturally cooling to obtain the black hierarchical carbon-coated silicon micro-nano composite anode material.
Example 3
The embodiment provides a hierarchical carbon-coated silicon micro-nano composite cathode material, which is formed by coating a nano silicon carbon aggregate on a nitrogen-doped lamellar carbon film, wherein the grain size of the nano silicon carbon is 100-500 nm, the grain size of the nano silicon carbon aggregate is 10-50 mu m, and the diameter of an in-situ grown carbon nanotube is 10-200 nm.
The invention also provides a preparation method of the hierarchical carbon-coated silicon micro-nano composite anode material, which comprises the following steps:
(1) adding 0.50g of nano silicon powder (with the particle size of 80-480 nm) into a mixed solution of 80ml of water containing 0.02g of polyvinylpyrrolidone, 320ml of ethanol and 4ml of ammonia water, stirring, ultrasonically dispersing uniformly, then adding 1.0g of resorcinol until the resorcinol is dissolved, finally adding 1.3g of formaldehyde solution, stirring and reacting at 30 ℃ for 24 hours, filtering, washing and drying to obtain precursor powder of the phenolic aldehyde coated silicon;
(2) and (3) grinding and uniformly mixing 0.15g of precursor powder, 1g of dicyandiamide and 0.08g of ferric nitrate, placing the mixture in a high-purity Ar atmosphere, preserving the heat at 850 ℃ for 5 hours, and naturally cooling to obtain the black hierarchical carbon-coated silicon micro-nano composite anode material.
Example 4
The embodiment provides a hierarchical carbon-coated silicon micro-nano composite cathode material, which is formed by coating a nano silicon carbon aggregate on a nitrogen-doped lamellar carbon film, wherein the grain size of the nano silicon carbon is 50-100 nm, the grain size of the nano silicon carbon aggregate is 5-20 mu m, and the diameter of an in-situ grown carbon nano tube is 10-100 nm.
The invention also provides a preparation method of the hierarchical carbon-coated silicon micro-nano composite anode material, which comprises the following steps:
(1) dispersing 0.2g dopamine hydrochloride in 400mL (with the concentration of 10mmol/L) trihydroxymethyl aminomethane buffer solution, then adding 0.60g nano silicon powder (with the particle size of 30-80 nm), ultrasonically dispersing uniformly, stirring for 5h at normal temperature, then repeatedly washing the obtained product with deionized water, centrifugally collecting, drying in a vacuum drying oven at 60 ℃ for 12h,
(2) and (3) grinding and uniformly mixing 0.20g of precursor powder, 3g of cyanamide and 0.2g of nickel chloride, placing the mixture in a high-purity Ar atmosphere, preserving the heat for 5 hours at 850 ℃, and naturally cooling to obtain the black hierarchical carbon-coated silicon micro-nano composite anode material.
Example 5
The embodiment provides a hierarchical carbon-coated silicon micro-nano composite cathode material, which is formed by coating a nano silicon carbon aggregate on a nitrogen-doped lamellar carbon film, wherein the grain size of the nano silicon carbon is 100-300 nm, the grain size of the nano silicon carbon aggregate is 10-30 mu m, and the diameter of an in-situ grown carbon nano tube is 10-150 nm.
The invention also provides a preparation method of the hierarchical carbon-coated silicon micro-nano composite anode material, which comprises the following steps:
(1) dispersing 0.2g of dopamine hydrochloride in 400mL (with the concentration of 10mmol/L) of trihydroxymethyl aminomethane buffer solution, then adding 0.40g of nano silicon powder (with the particle size of 80-280 nm), ultrasonically dispersing uniformly, stirring for 24 hours at normal temperature, then repeatedly washing the obtained product with deionized water, centrifugally collecting, and carrying out vacuum drying;
(2) and grinding and uniformly mixing 0.30g of precursor powder, 3g of melamine and 0.15g of ferric nitrate, placing the mixture in a high-purity Ar atmosphere, preserving heat for 3 hours at 600 ℃, and naturally cooling to obtain the black hierarchical carbon-coated silicon micro-nano composite negative electrode material.
Comparative example 1
The comparative example provides a preparation method of a silicon-superconducting carbon composite negative electrode material, which comprises the following steps: and (3) grinding or ball-milling 0.15g of nano silicon powder (with the particle size of 30-80 nm) and 0.10g of superconducting carbon for 1h to obtain the silicon-superconducting carbon composite negative electrode material.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A preparation method of a hierarchical carbon-coated silicon micro-nano composite anode material is characterized by comprising the following steps:
s1: adding nano silicon powder into a mixed solution containing a surfactant, stirring, performing ultrasonic treatment, sequentially adding resorcinol and formaldehyde solution, heating, stirring, filtering, washing and drying to obtain precursor powder of phenolic aldehyde coated silicon; the mixed solution consists of water, alcohol and ammonia water;
or adding the nano silicon powder into tris HCl buffer solution containing dopamine hydrochloride, stirring, performing ultrasonic treatment, performing heating reaction, filtering, washing and drying to obtain precursor powder of the poly-dopamine-coated nano silicon;
s2: and mixing the precursor powder with cyanamide micromolecules and iron transition metal salt, ball-milling or uniformly grinding, placing in an inert atmosphere, and performing heat treatment to obtain the hierarchical carbon-coated silicon micro-nano composite negative electrode material.
2. The method of claim 1, wherein in step S1, the molar ratio of resorcinol to formaldehyde is 1 (1-2); the mass ratio of the nano silicon powder to the resorcinol is (0.2-20) to 1; the ratio of the nano silicon powder to the mixed solution is (0.01-0.5) g:100 ml; the mass ratio of the surfactant to the mixed solution is (0.1-2): 100; the volume ratio of the alcohol to the water in the mixed solution is (50-1): 1, and the volume ratio of the ammonia water to the water is 1: (1-20).
3. The method according to claim 1 or 2, wherein in step S1, the surfactant is at least one of dodecyltrimethyl ammonium chloride, dodecyltrimethyl ammonium bromide, hexadecyltrimethyl ammonium chloride, hexadecyltrimethyl ammonium bromide, and polyvinylpyrrolidone.
4. The preparation method according to claim 1, wherein in step S1, the mass ratio of the nano silicon powder to the dopamine hydrochloride is 100 (5-50); the concentration of the tris HCl buffer solution is 5-20 mmol/L, and the pH value of the tris HCl buffer solution is 8-9.
5. The preparation method according to claim 1, wherein in step S1, the heating and stirring temperature is 20 to 80 ℃ and the time is 12 to 36 hours;
the heating reaction temperature is 10-60 ℃, and the time is 12-24 h.
6. The method according to claim 1, wherein in step S2, the molar ratio of the iron-based transition metal salt to the cyanamide-based small molecule is 1 (10-100); the mass ratio of the precursor powder to the cyanamide micromolecules is 1 (2-30).
7. The production method according to claim 1, wherein in step S2, the iron-based transition metal salt is at least one of cobalt nitrate, cobalt chloride, cobalt acetate, cobalt sulfate, iron nitrate, iron chloride, iron acetate, iron sulfate, nickel nitrate, nickel chloride, nickel acetate, and nickel sulfate; the cyanamide micromolecules are at least one of cyanamide, dicyandiamide and melamine.
8. The method of claim 1, wherein in step S2, the heat treatment temperature is 500-1000 ℃, the temperature rising rate is 1-5 ℃/min, and the time is 0.5-5 h.
9. A hierarchical carbon-coated silicon micro-nano composite anode material is characterized by being prepared by the preparation method of any one of claims 1-8; the composite cathode material comprises a nano silicon-carbon aggregate, wherein the nano silicon-carbon aggregate is a polymer formed by coating a carbon layer on the surface of a nano silicon particle; the carbon nano tube grows in situ in the nano silicon-carbon aggregate, and the surface of the nano silicon-carbon aggregate is uniformly coated by nitrogen-doped lamellar carbon.
10. An application of a hierarchical carbon-coated silicon micro-nano composite negative electrode material is characterized in that the composite negative electrode material prepared by the preparation method of any one of claims 1 to 8 or the composite negative electrode material of claim 9 is applied to a lithium ion battery.
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| CN115323779A (en) * | 2022-08-18 | 2022-11-11 | 南通大学 | Preparation method of cotton fabric for removing formaldehyde through light induction |
| CN115799474A (en) * | 2022-12-13 | 2023-03-14 | 大连理工大学 | Preparation method and application of fluorinated silicon-carbon negative electrode material |
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| CN111632581A (en) * | 2019-03-01 | 2020-09-08 | 江南大学 | Raspberry-like super-hydrophobic oleophylic cotton fiber oil-water adsorption/separation membrane and preparation method and application thereof |
| CN113860288A (en) * | 2021-11-05 | 2021-12-31 | 中国人民解放军国防科技大学 | Silicon-carbon nanotube composite negative electrode material and preparation method and application thereof |
| CN113980268A (en) * | 2021-11-18 | 2022-01-28 | 凯盛石墨碳材料有限公司 | Preparation method of polydopamine-coated nano-silicon and boric acid-modified polyaniline composite material |
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| CN111632581A (en) * | 2019-03-01 | 2020-09-08 | 江南大学 | Raspberry-like super-hydrophobic oleophylic cotton fiber oil-water adsorption/separation membrane and preparation method and application thereof |
| CN113860288A (en) * | 2021-11-05 | 2021-12-31 | 中国人民解放军国防科技大学 | Silicon-carbon nanotube composite negative electrode material and preparation method and application thereof |
| CN113980268A (en) * | 2021-11-18 | 2022-01-28 | 凯盛石墨碳材料有限公司 | Preparation method of polydopamine-coated nano-silicon and boric acid-modified polyaniline composite material |
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| CN115323779A (en) * | 2022-08-18 | 2022-11-11 | 南通大学 | Preparation method of cotton fabric for removing formaldehyde through light induction |
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| CN115799474A (en) * | 2022-12-13 | 2023-03-14 | 大连理工大学 | Preparation method and application of fluorinated silicon-carbon negative electrode material |
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