CN116314649A - Nitrogen-lithium co-doped silicon-carbon composite material and preparation method and application thereof - Google Patents

Nitrogen-lithium co-doped silicon-carbon composite material and preparation method and application thereof Download PDF

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CN116314649A
CN116314649A CN202211703910.7A CN202211703910A CN116314649A CN 116314649 A CN116314649 A CN 116314649A CN 202211703910 A CN202211703910 A CN 202211703910A CN 116314649 A CN116314649 A CN 116314649A
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刘忆恩
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Shanxi Wote Haimer New Materials Technology Co ltd
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Abstract

The invention discloses a preparation method of a nitrogen-lithium co-doped silicon-carbon composite material, which comprises the following steps: etching the surface of the nano silicon by using hydrofluoric acid steam to obtain carboxylated nano silicon; adhering carboxylated nano silicon to foam nickel by using an adhesive, and hot-pressing; wrapping polyaniline by adopting an electrochemical deposition method; lithium doping is carried out by adopting a hydrothermal reaction; carbonizing and crushing to obtain the nitrogen-lithium co-doped silicon-carbon composite material. The invention also discloses the composite material and application thereof. According to the invention, carboxylated nano silicon is adopted as a raw material, is connected with aniline through a chemical bond-Si-COO-N-, is electrochemically deposited on a polyaniline coated nano silicon complex, and is subjected to lithium salt deposition by a hydrothermal method, and finally carbonized, so that the coating layer has low impedance, high multiplying power, low irreversible capacity of the material and high first efficiency, and can be well used as a material of a lithium ion battery.

Description

Nitrogen-lithium co-doped silicon-carbon composite material and preparation method and application thereof
Technical Field
The invention belongs to the field of lithium ion battery materials, and particularly relates to a nitrogen-lithium co-doped silicon-carbon composite material, and a preparation method and application thereof.
Background
The silicon-carbon material has the advantages of high specific capacity (theoretical specific capacity 4200 Ah/g), wide material source, high safety performance (voltage platform is about 0.2V higher than graphite) and the like, and becomes one of the choices of the cathode materials of the lithium ion battery with high energy density, but when the silicon-carbon cathode undergoes alloying reaction, huge volume expansion (about 300%) occurs along with the phase change, and the serious volume change can bring a series of problems to the silicon-based cathode, such as crushing, pulverization, electrode coating falling and the like, and finally causes rapid capacity attenuation, thus seriously impeding the practical application of the silicon-carbon cathode in the lithium ion battery. Meanwhile, the silicon material is a semiconductor material, has poorer conductivity compared with a graphite material, has ion conductivity deviation, and has reduced efficiency for the first time due to irreversible lithium silicate formed by silicon and lithium, which seriously hinders the commercialized application of the silicon-based negative electrode.
Disclosure of Invention
Therefore, the invention aims to solve the technical problems of volume expansion, poor conductivity, low first efficiency and the like of the existing silicon-carbon material during reaction, thereby providing the nitrogen-lithium co-doped silicon-carbon composite material and the preparation method and the application thereof.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention provides a preparation method of a nitrogen-lithium co-doped silicon-carbon composite material, which comprises the following steps:
s1: etching the surface of the nano silicon by using hydrofluoric acid steam to obtain carboxylated nano silicon;
s2: the carboxylated nano-silicon is adhered to foam nickel by using an adhesive, and the carboxylated nano-silicon complex is formed by hot pressing;
s3: coating polyaniline on the surface of the carboxylated nano-silicon composite by adopting an electrochemical deposition method;
s4: mixing the polyaniline-coated carboxylated nano-silicon composite with an aminosilane coupling agent, ammonium persulfate and organic lithium salt in methyl ethyl carbonate, and performing hydrothermal reaction to obtain a lithium-doped polyaniline-coated carboxylated nano-silicon composite;
s5: carbonizing the lithium-doped polyaniline-coated carboxylated nano silicon composite, and crushing to obtain the nitrogen-lithium co-doped silicon-carbon composite material.
In step S1, the surface of the nano silicon is etched by using hydrofluoric acid steam, namely, the hydrofluoric acid is heated to 80-90 ℃ to form hydrofluoric acid steam, the surface of the nano silicon is etched, and the temperature is kept for 1-2 hours, so that carboxylated nano silicon is obtained.
In the step S2, the mass ratio of carboxylated nano silicon to binder to foam nickel is 100:1-10: 5-30 parts;
the hot pressing is carried out at 150 ℃ for 30min, and the pressure is 2T.
In the step S3, the electrochemical deposition method is to take carboxylated nano-silicon complex as a working electrode, 1-10wt% of aniline hydrochloric acid aqueous solution as a solution, saturated calomel as a counter electrode, and scan for 10-100 weeks under the condition of voltage range of-2V and scanning rate of 0.5-5 mV/S by a cyclic voltammetry;
the HCl in the hydrochloric acid aqueous solution is 1-10wt%.
In the step S4, the mass ratio of the polyaniline coated carboxylated nano-silicon complex to the aminosilane coupling agent, ammonium persulfate and organic lithium salt is 100:1-5:1-5:5-20;
the hydrothermal reaction temperature is 100-200 ℃ and the reaction time is 1-6 h;
wherein methyl ethyl carbonate can also be replaced by propylene carbonate and ethylene carbonate.
In step S5, the carbonization is performed at 800 ℃ for 6 hours.
Preferably, the aminosilane coupling agent is one of 3-aminopropane triethoxysilane, 3-aminopropane trimethoxysilane, (3-aminopropane) methyldiethoxysilane;
the organic lithium salt is one of lithium methoxide, lithium ethoxide, lithium formate, lithium oxalate or lithium stearate;
the binder is one of asphalt, polyvinyl alcohol, CMC-Li binder, LA136D binder or beta-cyclodextrin.
The invention also provides a nitrogen-lithium co-doped silicon-carbon composite material, which is prepared according to the preparation method.
Further, in the nitrogen-lithium co-doped silicon-carbon composite material, the mass ratio of nano silicon to nitrogen doped amorphous carbon to lithium salt is 80-95:3.8-18.1:0.5-4.6.
The invention also provides application of the nitrogen-lithium co-doped silicon-carbon composite material to a lithium ion battery.
The technical scheme of the invention has the following advantages:
(1) The invention adopts carboxylated nano silicon as raw material, which is connected with aniline through chemical bond-Si-COO-N-and is coated with nano silicon compound on the surface through electrochemical deposition, and finally carbonized to obtain the silicon-carbon material.
(2) According to the invention, lithium salt is deposited on the polyaniline-coated nano silicon surface by adopting a hydrothermal method, so that the irreversible capacity of the material is reduced, and the first efficiency is improved. Meanwhile, the foam nickel current collector plays a catalytic role in the carbonization process, and the reaction process is improved. Meanwhile, polyaniline coated nano silicon and an aminosilane coupling agent form a three-dimensional network structure through the polymerization of ammonium persulfate, and the three-dimensional porous silicon-carbon composite material is obtained through carbonization.
(3) When lithium salt is deposited by using a hydrothermal method, the polyaniline-coated nano silicon composite material and the aminosilane coupling agent undergo polymerization reaction under the condition of ammonium persulfate to obtain a polyaniline composite body of the silane coupling agent, so that the polyaniline composite body forms a network structure. Meanwhile, a hydrothermal method is adopted to prepare the nitrogen-lithium co-doped silicon-carbon composite material by using a solution of polyaniline coated nano silicon composite material, an aminosilane coupling agent, ammonium persulfate and methyl ethyl carbonate of organic lithium salt through the hydrothermal method, so that uniform mixing among materials can be realized, and the reaction is more complete.
(4) According to the invention, finally, polyaniline, lithium salt and silicon-based material complex thereof are carbonized, so that polyaniline can be converted into carbon, and the lithium salt is utilized for prelithiation, so that the irreversible capacity is reduced, the first efficiency is improved, and uniform mixing among materials can be realized. The nitrogen-lithium co-doped silicon-carbon composite material is obtained by one-step carbonization, the problems of complex multiple carbonization processes and slow preparation period are avoided, and the method has the advantages of high reaction speed, good uniformity and the like.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
Fig. 1 is an SEM image of the lithium nitrogen co-doped silicon carbon composite material obtained in example 1.
Detailed Description
The following examples are provided for a better understanding of the present invention and are not limited to the preferred embodiments described herein, but are not intended to limit the scope of the invention, any product which is the same or similar to the present invention, whether in light of the present teachings or in combination with other prior art features, falls within the scope of the present invention.
The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field.
Example 1
The embodiment provides a nitrogen-lithium co-doped silicon-carbon composite material, which is prepared by the following steps:
(1) Heating hydrofluoric acid to 80 ℃ to form hydrofluoric acid steam, then introducing the hydrofluoric acid steam into a plastic vessel containing nano silicon, preserving heat for 1h, and then washing with deionized water to obtain carboxylated nano silicon with etched surface;
(2) 100g of carboxylated nano-silicon and 5g of asphalt (softening point: 150 ℃) are uniformly mixed and coated on 20g of foam nickel, and then a hot press is used for hot pressing for 30min at the temperature of 150 ℃ under the pressure of 2T, so as to obtain a carboxylated nano-silicon composite;
(3) Taking the carboxylated nano-silicon composite as a working electrode, taking 5wt% of aniline hydrochloric acid aqueous solution as a solvent (the HCl in the hydrochloric acid aqueous solution is 5 wt%) and saturated calomel as a counter electrode, scanning for 50 weeks under the condition of a voltage range of-2V-2V and a scanning rate of 1mV/s by cyclic voltammetry, filtering, and washing with deionized water to obtain the polyaniline-coated carboxylated nano-silicon composite material;
(4) Adding 10g of lithium methoxide into 100g of methyl ethyl carbonate solution for uniform dispersion, adding 100g of polyaniline-coated carboxylated nano-silicon composite material, 3g of 3-aminopropane triethoxysilane and 3g of ammonium persulfate for uniform mixing, transferring into a high-pressure reaction kettle, carrying out hydrothermal reaction for 3 hours at the temperature of 150 ℃, and filtering to obtain a lithium-doped polyaniline-coated carboxylated nano-silicon composite body;
(5) Carbonizing the lithium-doped polyaniline-coated carboxylated nano-silicon composite for 6 hours at 800 ℃, and crushing to obtain the nitrogen-lithium co-doped silicon-carbon composite material.
Example 2
The embodiment provides a nitrogen-lithium co-doped silicon-carbon composite material, which is prepared by the following steps:
(1) Heating hydrofluoric acid to 90 ℃ to form hydrofluoric acid steam, then introducing the hydrofluoric acid steam into a plastic vessel containing nano silicon, preserving heat for 2 hours, and then washing with deionized water to obtain carboxylated nano silicon with etched surface;
(2) Uniformly mixing 100g of carboxylated nano silicon and 1g of polyvinyl alcohol, coating the mixture on 15g of foam nickel, and then carrying out hot pressing for 30min at the temperature of 150 ℃ under the pressure of 2T by using a hot press to obtain a carboxylated nano silicon composite;
(3) Taking the carboxylated nano-silicon composite as a working electrode, taking 1wt% of aniline hydrochloric acid aqueous solution as a solvent (1 wt% of HCl in the hydrochloric acid aqueous solution) and saturated calomel as a counter electrode, scanning for 10 weeks under the condition of a voltage range of-2V-2V and a scanning rate of 0.5mV/s by cyclic voltammetry, filtering, and washing with deionized water to obtain the polyaniline-coated carboxylated nano-silicon composite material;
(4) Adding 5g of lithium ethoxide into 100g of methyl ethyl carbonate solution, dispersing uniformly, adding 100g of polyaniline-coated carboxylated nano-silicon composite material, 1g of 3-aminopropane trimethoxy silane and 1g of ammonium persulfate, mixing uniformly, transferring into a high-pressure reaction kettle, performing hydrothermal reaction at the temperature of 100 ℃ for 6 hours, and filtering to obtain a lithium-doped polyaniline-coated carboxylated nano-silicon composite;
(5) Carbonizing the lithium-doped polyaniline-coated carboxylated nano-silicon composite for 6 hours at 800 ℃, and crushing to obtain the nitrogen-lithium co-doped silicon-carbon composite material.
Example 3
The embodiment provides a nitrogen-lithium co-doped silicon-carbon composite material, which is prepared by the following steps:
(1) Heating hydrofluoric acid to 85 ℃ to form hydrofluoric acid steam, then introducing the hydrofluoric acid steam into a plastic vessel containing nano silicon, preserving heat for 1h, and then washing with deionized water to obtain carboxylated nano silicon with etched surface;
(2) Uniformly mixing 100g of carboxylated nano silicon and 10g of CMC-Li, coating the mixture on 30g of foam nickel, and then carrying out hot pressing for 30min at the temperature of 150 ℃ under the pressure of 2T by using a hot press to obtain a carboxylated nano silicon composite;
(3) Taking the carboxylated nano-silicon composite as a working electrode, taking a 10wt% aniline hydrochloric acid aqueous solution as a solvent (the HCl in the hydrochloric acid aqueous solution is 10 wt%) and saturated calomel as a counter electrode, scanning for 100 weeks under the condition of a voltage range of-2V-2V and a scanning rate of 5mV/s by cyclic voltammetry, filtering, and washing with deionized water to obtain the polyaniline-coated carboxylated nano-silicon composite material;
(4) Adding 20g of lithium oxalate into 100g of methyl ethyl carbonate solution for uniform dispersion, then adding 100g of polyaniline-coated carboxylated nano-silicon composite material, 5g of (3-aminopropane) methyldiethoxysilane and 5g of ammonium persulfate for uniform mixing, transferring into a high-pressure reaction kettle, carrying out hydrothermal reaction at the temperature of 200 ℃ for 1h, and filtering to obtain a lithium-doped polyaniline-coated carboxylated nano-silicon composite;
(5) Carbonizing the lithium-doped polyaniline-coated carboxylated nano-silicon composite for 6 hours at 800 ℃, and crushing to obtain the nitrogen-lithium co-doped silicon-carbon composite material.
Comparative example 1
The comparative example provides a lithium doped silicon carbon composite material, the preparation method of which specifically comprises the following steps:
100g of nano silicon, 3g of 3-aminopropane-methyl diethoxysilane, 10g of lithium methoxide and 100g of methyl ethyl carbonate are uniformly mixed, transferred into a high-pressure reaction kettle, subjected to hydrothermal reaction at 150 ℃ for 3 hours, filtered, carbonized at 800 ℃ for 6 hours, and crushed to obtain the lithium doped silicon carbon composite material.
Comparative example 2
The comparative example provides a nitrogen-doped silicon-carbon composite material, which is different from the example 1 in that the polyaniline-coated carboxylated nano-silicon composite material obtained in the step (3) is directly carbonized at 800 ℃ for 6 hours, and crushed to obtain the nitrogen-doped silicon-carbon composite material.
Comparative example 3
This comparative example provides a lithium-doped silicon-carbon composite material, differing from example 1 in that the carboxylated nano-silicon composite material is not coated with polyaniline, and the hydrothermal reaction of step (4) is directly performed after the carboxylated nano-silicon composite material is obtained in step (2).
Comparative example 4
This comparative example provides a nitrogen lithium co-doped silicon carbon composite material, which differs from example 1 in that no etching is performed on the nano-silicon surface.
Comparative example 5
The comparative example provides a nitrogen-lithium co-doped silicon-carbon composite material, which is different from the example 1 in that polyaniline is coated with carboxylated nano-silicon composite material by using a liquid phase method, and the specific preparation method is as follows:
(1) Heating hydrofluoric acid to 80 ℃ to form hydrofluoric acid steam, then introducing the hydrofluoric acid steam into a plastic vessel containing nano silicon, preserving heat for 1h, and then washing with deionized water to obtain carboxylated nano silicon with etched surface;
(2) 100g of carboxylated nano-silicon and 5g of asphalt (softening point: 150 ℃) are uniformly mixed and coated on 20g of foam nickel, and then a hot press is used for hot pressing for 30min at the temperature of 150 ℃ under the pressure of 2T, so as to obtain a carboxylated nano-silicon composite;
(3) Adding 10g of polyaniline to 100g of N-methylpyrrolidone, uniformly dispersing, adding 100g of carboxylated nano-silicon composite, uniformly dispersing by ultrasonic, filtering, and drying in vacuum to obtain the polyaniline-coated carboxylated nano-silicon composite;
(4) Adding 10g of lithium methoxide into 100g of methyl ethyl carbonate solution for uniform dispersion, adding 100g of polyaniline-coated carboxylated nano-silicon composite material, 3g of 3-aminopropane triethoxysilane and 3g of ammonium persulfate for uniform mixing, transferring into a high-pressure reaction kettle, carrying out hydrothermal reaction for 3 hours at the temperature of 150 ℃, and filtering to obtain a lithium-doped polyaniline-coated carboxylated nano-silicon composite body;
(5) Carbonizing the lithium-doped polyaniline-coated carboxylated nano-silicon composite for 6 hours at 800 ℃, and crushing to obtain the nitrogen-lithium co-doped silicon-carbon composite material.
Test example 1
SEM test was conducted on the lithium nitrogen co-doped silicon carbon composite material prepared in example 1, and the test results are shown in FIG. 1. As can be seen from FIG. 1, the composite material prepared in example 1 has a concave granular structure, has a relatively uniform size distribution, and has a particle size of 2-10 μm.
Test example 2
Physical and chemical properties:
the silicon-carbon composite materials prepared in examples 1 to 3 and comparative examples 1 to 5 were subjected to particle size, compacted density, specific surface area, trace element nitrogen content. The test is carried out according to the method of the national standard GBT-38823-2020 silicon carbide. The test results are shown in Table 1.
TABLE 1 physicochemical Properties of silicon carbon composite Material
Figure BDA0004025592530000091
Figure BDA0004025592530000101
Test example 3
Button cell test:
the silicon-carbon composite materials in examples 1-3 and comparative examples 1-5 are used as negative electrode materials of lithium ion batteries to be assembled into button batteries, and the specific preparation method of the negative electrode materials is as follows: adding binder, conductive agent and solvent into the composite material, stirring to slurry, coating on copper foil, oven drying, and rolling. The adhesive is LA132 adhesive, the conductive agent SP, the solvent is secondary distilled water, and the composite material is prepared from the following components: SP: LA132: secondary distilled water = 90g:4g:6g:220mL, preparing a negative electrode plate; a metal lithium sheet is used as a positive electrode; the electrolyte adopts LiPF6/EC+DEC, the LiPF6 in the electrolyte is electrolyte, the mixture of EC and DEC with the volume ratio of 1:1 is solvent, and the electrolyte concentration is 1.3mol/L; the diaphragm adopts a composite film of polyethylene PE, polypropylene PP or polyethylene propylene PEP. The button cell assembly was performed in an argon filled glove box. Electrochemical performance was performed on a wuhan blue CT2001A battery tester with a charge-discharge voltage ranging from 0.005V to 2.0V and a charge-discharge rate of 0.1C, testing the first discharge capacity and first efficiency of the coin cell battery, and simultaneously testing the rate capability (5C, 0.1C) and cycle performance (0.5C/0.5C, 200 times), and the coin cell battery was subjected to an anatomic test for the expansion rate of the negative electrode sheet under 100% soc of full charge. The test results are shown in Table 2.
TABLE 2 button cell performance
Figure BDA0004025592530000102
Figure BDA0004025592530000111
As can be seen from tables 1 and 2, the material prepared by the embodiment of the invention has high specific capacity and first efficiency, and is characterized in that the doped lithium compound in the material improves the first efficiency, the nitrogen reduces the impedance, thereby reducing the battery platform and improving the multiplying power and the first efficiency, and the electrochemical deposition method has the characteristic of high deposition density, so that the compaction density of the material is improved, and the polyaniline is deposited on the surface of the material by adopting electrochemical deposition, thereby improving the multiplying power performance and the cycle performance. Comparative examples 1-3 lack the specific steps of the examples, which result in material properties that are significantly lower than the examples; in comparative example 4, nano silicon is directly used instead of carboxylated nano silicon, the density of aniline deposited on the surface of nano silicon is poor, and the impedance is larger; in comparative example 5, polyaniline was precipitated by a liquid phase method, and because of the small particle size of silicon, the agglomeration easily caused poor coating uniformity, and the impedance and expansion were high.
Test example 4
Soft package battery test:
(1) The silicon-carbon composite materials of examples 1 to 3 and comparative examples 1 to 5 were blended with 90% of artificial graphite as a negative electrode, and were subjected to slurry mixing and coating to prepare a negative electrode sheet, which was made of ternary materials (LiNi 1/3 Co 1/3 Mn 1/3 O 2 ) As positive electrode, with LiPF 6 (the solvent is EC+DEC, the volume ratio is 1:1, the electrolyte concentration is 1.3 mol/L) is taken as electrolyte, and a Celgard2400 membrane is taken as a diaphragm, so that the 2Ah soft-package battery is prepared.
(2) And (3) multiplying power performance test:
the rate performance of the soft package battery is tested, the charging and discharging voltage ranges from 2.5V to 4.2V, the temperature is 25+/-3.0 ℃, the charging is carried out at 1.0C, 3.0C, 5.0C and 10.0C, and the discharging is carried out at 1.0C. The results are shown in Table 3.
Table 3 soft pack battery performance test
Figure BDA0004025592530000121
As can be seen from table 3, the rate charging performance of the soft pack batteries prepared from the materials of examples 1 to 3 is significantly better than that of comparative examples 1 to 5, i.e., the charging time is shorter, because of the analysis: lithium ions are required to migrate in the battery charging process, and the material surface in each embodiment is coated with lithium salt, so that the material has the characteristics of high deposition density, low impedance and the like, and the rate capability is improved.
(3) And (3) testing the cycle performance:
and (3) testing the cycle performance of the obtained soft package battery, wherein the conditions are as follows: the charge-discharge current is 2C/2C, the voltage range is 2.5-4.2V, the cycle number is 1000 times, and the test result is shown in Table 4.
Table 4 cycle performance test
Figure BDA0004025592530000131
It can be seen from Table 4 that the cycle performance of the lithium ion batteries prepared using the composite materials obtained in examples 1 to 3 was significantly better at each stage than that of the comparative example. Experimental results show that the method can be used for depositing polyaniline on the surface of the nano silicon by an electrochemical deposition method, doping lithium salt by a hydrothermal method, so that the content of lithium ions in the charge and discharge process can be improved, and the cycle performance can be improved.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.

Claims (10)

1. The preparation method of the nitrogen-lithium co-doped silicon-carbon composite material is characterized by comprising the following steps of:
s1: etching the surface of the nano silicon by using hydrofluoric acid steam to obtain carboxylated nano silicon;
s2: the carboxylated nano-silicon is adhered to foam nickel by using an adhesive, and the carboxylated nano-silicon complex is formed by hot pressing;
s3: coating polyaniline on the surface of the carboxylated nano-silicon composite by adopting an electrochemical deposition method to obtain the polyaniline coated carboxylated nano-silicon composite;
s4: mixing the polyaniline-coated carboxylated nano-silicon composite with an aminosilane coupling agent, ammonium persulfate and organic lithium salt in methyl ethyl carbonate, and performing hydrothermal reaction to obtain a lithium-doped polyaniline-coated carboxylated nano-silicon composite;
s5: carbonizing the lithium-doped polyaniline-coated carboxylated nano silicon composite, and crushing to obtain the nitrogen-lithium co-doped silicon-carbon composite material.
2. The preparation method of claim 1, wherein in step S1, hydrofluoric acid vapor is used to etch the nano silicon surface, specifically, hydrofluoric acid is heated to 80-90 ℃ to form hydrofluoric acid vapor, and the nano silicon surface is etched and kept for 1-2 hours to obtain carboxylated nano silicon.
3. The preparation method according to claim 2, wherein in the step S2, the mass ratio of carboxylated nano-silicon, the binder and the foam nickel is 100:1-10:5-30;
the hot pressing is carried out at 150 ℃ for 30min, and the pressure is 2T.
4. The method according to claim 3, wherein in the step S3, the electrochemical deposition method is to scan for 10 to 100 weeks under the conditions of a voltage range of-2V to 2V and a scanning rate of 0.5 to 5mV/S by cyclic voltammetry using carboxylated nano-silicon complex as a working electrode, an aniline hydrochloric acid aqueous solution of 1 to 10wt% as a counter electrode;
the HCl in the hydrochloric acid aqueous solution is 1-10wt%.
5. The preparation method of claim 4, wherein in the step S4, the mass ratio of the polyaniline-coated carboxylated nano-silicon complex to the aminosilane coupling agent, ammonium persulfate and organic lithium salt is 100:1-5:1-5:5-20;
the hydrothermal reaction temperature is 100-200 ℃ and the reaction time is 1-6 h.
6. The method according to claim 5, wherein in step S5, the carbonization is performed at 800℃for 6 hours.
7. The method according to claim 6, wherein the aminosilane coupling agent is one of 3-aminopropane triethoxysilane, 3-aminopropane trimethoxysilane, (3-aminopropane) methyldiethoxysilane;
the organic lithium salt is one of lithium methoxide, lithium ethoxide, lithium formate, lithium oxalate or lithium stearate;
the binder is one of asphalt, polyvinyl alcohol, CMC-Li binder, LA136D binder or beta-cyclodextrin.
8. A lithium nitrogen co-doped silicon carbon composite material, characterized in that it is produced according to the production method of any one of claims 1 to 7.
9. The nitrogen-lithium co-doped silicon-carbon composite material according to claim 8, wherein the mass ratio of nano silicon, nitrogen-doped amorphous carbon and lithium salt in the nitrogen-lithium co-doped silicon-carbon composite material is 80-95:3.8-18.1:0.5-4.6.
10. Use of the lithium nitrogen co-doped silicon carbon composite material according to claim 8 or 9, in a lithium ion battery.
CN202211703910.7A 2022-12-29 2022-12-29 Nitrogen-lithium co-doped silicon-carbon composite material and preparation method and application thereof Pending CN116314649A (en)

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