CN114695858A - High-performance lithium ion battery negative electrode material and preparation method thereof - Google Patents
High-performance lithium ion battery negative electrode material and preparation method thereof Download PDFInfo
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Abstract
The invention provides a high-performance lithium ion battery cathode material which has a structure that nano silver particles are anchored on the inner wall of a hollow carbon sphere, wherein Ag and carbon both have high electronic conductivity, so that charge transmission in the charge-discharge process is facilitated, and polarization is reduced. The hollow structure provides enough lithium storage space, prevents lithium from depositing outside the carbon layer to generate dendrite and dead lithium, and relieves the volume strain in the circulating process. The invention also provides a preparation method of the high-performance lithium ion battery cathode material, wherein the preparation of the one-dimensional nanowire is realized by adopting an electrostatic spinning technology, and the preparation of the three-dimensional honeycomb structure material is realized by adopting a freeze drying technology. The preparation method of the cathode material is simple and is easy to realize industrial scale production.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a high-performance lithium ion battery cathode material and a preparation method thereof.
Background
Lithium ion batteries have the advantages of high power, high energy density, low self-discharge, long cycle life, etc., and have become the most widely used secondary battery technology at present. The lithium-free negative electrode has attracted the interest of numerous researchers because the energy density of the lithium-free negative electrode can be greatly improved compared with the traditional negative electrode material of the lithium ion battery at present and the advantage of high specific capacity of lithium metal is fully exerted.
In a lithium-free negative electrode battery, all active lithium is initially stored in the positive electrode material, and during initial charging, the active lithium diffuses from the positive electrode to the negative electrode and is plated directly in situ on the bare current collector. Despite the absence of excess lithium in a lithium-free negative electrode battery, all active lithium being derived from the positive electrode material, many challenges remain: the uneven deposition of lithium accelerates the formation and growth of lithium dendrites, generates dead lithium, and reduces the utilization rate of lithium; the lithium precipitation process is accompanied by large volume strain, repeated breakage and regeneration of a solid electrolyte interface film (SEI), irreversible loss of electrolyte and active lithium, and the like. The above problems will deteriorate the battery performance and even bring about safety hazards. Therefore, in order to solve these problems, it is important to optimize the composition and structure of the lithium-free negative electrode and to develop a high-performance lithium ion secondary battery.
In view of this, the invention is particularly proposed.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a high-performance lithium ion battery cathode material. The lithium ion battery has a honeycomb porous structure, and can induce ordered deposition of lithium in the charging and discharging processes of the lithium ion battery, so that the formation and growth of lithium dendrites are inhibited. The electrochemical performance of the battery prepared by the cathode is outstanding: the 10C high-rate discharge can be realized, the 5C charge-discharge cycle life reaches more than 1000 times, and the 1000 th cycle coulombic efficiency reaches more than 95%. The preparation method of the cathode material is simple and easy to realize industrial scale production.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the invention relates to a high-performance lithium ion battery cathode material, which is a two-dimensional material formed by interweaving and stacking one-dimensional nanowires and has a porous structure;
the one-dimensional nanowires are formed by arranging spherical particles in a chain shape, the spherical particles are hollow nanospheres and comprise a shell and metal particles deposited on the inner wall of the shell, and the shell is made of carbon.
Preferably, the size of the holes of the two-dimensional material is 1-10 mu m, and the specific surface area is 20-100 m2/g。
Preferably, the length of the one-dimensional nanowire is 10-30 μm, and the radius of the one-dimensional nanowire is 100-300 nm.
Preferably, the shell material is amorphous carbon, and the material of the metal particles is selected from any one of Ag, Au, Zn, and Mg.
Preferably, the size of the spherical particles is 100-300 nm, the thickness of the shell is 1-10 nm, and the size of the metal particles is 5-15 nm.
The invention also relates to a preparation method of the high-performance anode material, which comprises the following steps:
step one, SiO2Placing the nano powder in SnCl2In the aqueous solution, a first mixed solution is prepared by ultrasonic dispersion;
preferably, the SiO2The particle size of the nano powder is 100-300 nm. SiO 22The nanometer powder as template determines the size of the spherical particle and the lithium storing space, and the subsequent SiO2The nano-powder is removed by etching. The Sn2+Having reducing properties, followed by the addition of Ag as a reducing agent+Reducing the silver into metallic silver.
Preferably, the SiO2Nano powder and SnCl2The molar ratio of (1-5) to (1).
Step two, sequentially centrifuging, filtering and cleaning the first mixed solution prepared in the step one to obtain Sn2+Sensitized SiO2A nanoparticle;
preferably, the washing is performed for 3-5 times by using distilled water and/or ethanol.
Step three, Sn2+Sensitized SiO2Adding the nano particles into deionized water, and performing ultrasonic dispersion to prepare a second mixed solution;
step four, AgNO is added3Placing the mixture into deionized water, dropwise adding ammonia water, and performing ultrasonic dispersion to obtain ammoniated AgNO3A solution;
preferably, the AgNO3The molar ratio of the ammonia to the ammonia is (0.5-1): 1, and the concentration of the ammonia water is1-3 mol/L of ammoniated AgNO3The concentration is 0.5-2 mol/L. Can be controlled by AgNO3The concentration of the solution and the addition of ammonia water control the size and the quantity of the final nano Ag particles.
Step five, adding the ammoniated AgNO prepared in the step four into the second mixed solution prepared in the step three3The solution is stirred, centrifuged, filtered and washed in sequence at room temperature to prepare SiO2@ Ag composite material;
preferably, the second mixed liquor and ammoniated AgNO3In solution, SiO2Nano powder and AgNO3The molar ratio of (2-5) to (1). In this process, the sensitized SiO2Sn of the surface2+Has high reducibility, and can displace Ag from solution and uniformly deposit on SiO2And forming Ag nano particles on the surface layer.
Step six, taking the SiO2The @ Ag composite material is put into a solution with N, N-Dimethylformamide (DMF) as a solvent and Polyacrylonitrile (PAN) as a solute, and the solution is mixed to prepare a spinning precursor solution;
preferably, the SiO2The mass ratio of the @ Ag composite material to the PAN is (1-3): 1, and the mass ratio of the DMF to the PAN is (10-15): 1.
Preferably, the mixing is carried out for 10-15 hours at the temperature of 55-65 ℃. Through the steps, the surface layer of the composite material is wrapped by PAN, so that the preparation of the amorphous carbon shell containing the N functional group is realized later.
Step seven, performing electrostatic spinning by using the spinning precursor solution prepared in the step six to obtain fiber yarns;
preferably, the flow rate of the electrostatic spinning is 0.5-1.5 ml/h, and the spinning voltage is 14-17 kV. Through the steps, the preparation of the one-dimensional nano framework material with certain strength is realized, and conditions are provided for the self-assembly molding of the subsequent two-dimensional material. By the optimized design of the spinning process parameters, the diameter and the length of the nanowire are controllable, the strength and the dispersibility of the one-dimensional material are ensured, and conditions are provided for the self-assembly molding of the subsequent two-dimensional material.
Step eight, collecting the fiber filaments prepared in the step seven, and calcining the fiber filaments in an inert atmosphere to prepare C @ SiO2@ Ag nanowire;
preferably, the inert atmosphere is nitrogen or argon, the calcining temperature is 600-850 ℃, and the time is 2-4 hours. And carbonizing PAN into a porous amorphous carbon protective layer by controlling the calcining temperature and time, wherein the outer layer of the carbon shell is provided with a lithium-philic N-containing functional group. Not only ensures good electronic conductivity, but also is beneficial to Li in the charging and discharging process+Diffusion transport inside and outside the carbon shell.
And step nine, adding the nanowires prepared in the step eight into a KOH or NaOH aqueous solution, and standing to obtain a third mixed solution.
Preferably, the molar concentration of the KOH or NaOH aqueous solution is 3-8 mol/L, the standing temperature is 65-75 ℃, and the time is 46-60 h. By which SiO is oxidized2Etching and dissolving, and reserving high-conductivity components C and Ag to realize the preparation of the hollow carbon sphere inner wall anchoring silver particle structure.
And step ten, centrifuging and cleaning the third mixed solution, and adding deionized water to prepare a fourth mixed solution with higher viscosity.
Preferably, the viscosity of the fourth mixed solution is 1000 to 7000 mpa.s. The viscosity affects the rheological properties of the slurry, and further affects the surface roughness, porosity and thickness of the finally formed negative electrode.
And step eleven, blade-coating the fourth mixed solution on the surface of a carrier, freeze-drying to form a sheet containing the high-performance negative electrode material, peeling the sheet from the surface of the carrier, and cutting to obtain the negative electrode plate of the lithium ion battery.
Preferably, the carrier is a copper foil.
Preferably, the temperature of the freeze drying is-40 to-20 ℃, and the time is 24 to 36 hours. Through the step, water in the fourth mixed solution is crystallized and sublimated, and the preparation of the honeycomb three-dimensional structure is completed. And regulating and controlling the size of the three-dimensional structure hole by adjusting the proportion of the nanowire and the water in the fourth mixed solution.
Compared with the prior art, the technical scheme of the invention has the beneficial effects that:
the invention provides a high-performance lithium ion battery cathode material, which is prepared fromThe structure of the hollow carbon sphere inner wall anchoring nano silver particles has the following advantages: (1) ag and carbon both have high electronic conductivity, and amorphous carbon can realize Li+The shuttling is beneficial to charge transmission in the charging and discharging process, and the polarization is reduced; (2) the N-containing functional group outside the carbon shell has higher binding energy with lithium, provides lithium-philic sites, reduces the nucleation energy barrier of lithium and guides the ordered deposition of lithium; (3) ag can reduce the deposition overpotential of lithium, eliminate the lithium nucleation barrier, induce lithium to deposit in the carbon shell and prevent the formation of dendritic crystals; (4) the hollow structure provides enough lithium storage space, prevents lithium from depositing outside the carbon layer, generates dendrite and dead lithium, and relieves the volume strain in the circulation process.
The invention also provides a preparation method of the high-performance lithium ion battery cathode material, wherein the preparation of the one-dimensional nanowire is realized by adopting an electrostatic spinning technology, and the preparation method has the following advantages: (1) as a framework supporting structure, the one-dimensional nanowires form a two-dimensional material in an interweaving and stacking mode, so that the strength of the two-dimensional material is ensured, and the structural stability of the material is ensured; (2) the specific surface area of the material is improved, and the local current density is reduced.
The preparation method also comprises a freeze drying technology, realizes the preparation of the three-dimensional honeycomb structure material, and has the following advantages: (1) the specific surface area of the material is increased, the current density in the average structure is increased, and the polarization is reduced, so that the material has the ultrahigh multiplying power characteristic; (2) the pores in the two-dimensional material can induce ordered deposition of lithium, act as a "secondary barrier", further inhibit formation and growth of lithium dendrites, and provide a buffer space for electrode expansion.
The preparation method provided by the invention can realize the preparation of the high-performance cathode material. The preparation method of the cathode material is simple and easy to realize industrial scale production.
In conclusion, the structure and the component design realize the ordered deposition of lithium, effectively inhibit the growth of lithium dendrites and the volume effect of the circulation process, and therefore, the multiplying power and the cyclicity of the battery are obviously improved. In addition, metals other than Ag, such as Au, Zn, and Mg, have low lithium deposition overpotentials, can induce ordered deposition of lithium, and are metal materials that have attracted much attention in the development of lithium alloys. The invention provides an idea for the design of a hollow carbon sphere coated with Au, Zn, Mg nano-particles and other novel structure cathode materials.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.
Example 1
A preparation method of a high-performance anode material comprises the following steps:
step one, preparing 0.1mol/L SnCl250ml of an aqueous solution, 0.01mol of SiO are added2And (4) dispersing the nano powder for 30min by ultrasonic to prepare a first mixed solution. The particle size of the selected silicon dioxide is 200 nm;
step two, centrifuging and filtering the first mixed solution, and washing the mixture for a plurality of times by using distilled water and ethanol to obtain Sn2+Sensitized SiO2Nanoparticles, centrifuge speed 6000 rpm.
Step three, sensitizing the SiO2Putting the nano particles into 10ml of deionized water, and performing ultrasonic dispersion for 30min to prepare a second mixed solution;
step four, mixing 0.003molAgNO3Adding into 0.5ml deionized water, dropwise adding 2.5ml ammonia water (ammonia water concentration of 6 wt%), ultrasonic dispersing for 30min to obtain ammoniated AgNO3Solution of AgNO3The concentration is 1 mol/L.
Step five, adding the second mixed solution prepared in the step three into the ammoniated AgNO prepared in the step four3Stirring in the solution at room temperature for 1h, centrifuging, filtering, and repeatedly washing with deionized water and ethanol to obtain SiO2@ Ag composite material. The grain diameter of the Ag particles is 5-10 nm.
And step six, taking 0.3g of the composite material, putting into 2.5ml of DMF solution, and performing ultrasonic dispersion. Then 0.2g PAN was added and stirred at 60 ℃ for 12h to obtain a spinning precursor solution.
And seventhly, performing electrostatic spinning by using the spinning precursor solution prepared in the sixth step to obtain the fiber yarn. The spinning parameters are as follows: the flow rate is 1ml/h, and the spinning voltage is 15 kV.
Step eight, collecting the fiber filaments, calcining for 3 hours at 750 ℃ in Ar atmosphere to prepare C @ SiO2@ Ag one-dimensional composite material;
and step nine, adding the one-dimensional material into 50ml of 5mol/l KOH solution, and preserving the heat at 70 ℃ for 48 hours to obtain a third mixed solution.
And step ten, centrifuging and cleaning the third mixed solution, and adding deionized water to prepare a fourth mixed solution with the viscosity of 6000 mPa.s.
And step eleven, coating the fourth mixed solution prepared in the step eleven on a Cu foil in a coating thickness of 400 microns, quickly immersing in liquid nitrogen, freeze-drying for 24 hours, and tearing off the Cu foil by using tweezers to obtain the final negative electrode material. SEM test results show that the honeycomb-shaped pore size of the two-dimensional material is about 1 μm.
Example 2
A preparation method of a high-performance anode material comprises the following steps:
step one, preparing 0.1mol/L SnCl250ml of an aqueous solution, 0.01mol of SiO are added2And (4) dispersing the nano powder for 30min by ultrasonic to prepare a first mixed solution. The particle size of the selected silicon dioxide is 200 nm;
step two, centrifuging and filtering the first mixed solution, and washing the mixture for a plurality of times by using distilled water and ethanol to obtain Sn2+Sensitized SiO2Nanoparticles, centrifuge speed 6000 rpm.
Step three, sensitizing the SiO2Putting the nano particles into 10ml of deionized water, and performing ultrasonic dispersion for 30min to prepare a second mixed solution;
step four, mixing 0.003molAgNO3Adding into 0.5ml deionized water, dropwise adding 2.5ml ammonia water (ammonia water concentration of 6 wt%), ultrasonic dispersing for 30min to obtain ammoniated AgNO3And (3) solution. Wherein AgNO3The concentration is 1 mol/L.
Step five, adding the second mixed solution prepared in the step three into the ammoniated AgNO prepared in the step four3In solution, chamberStirring for 1h at the temperature, centrifuging, filtering, and repeatedly cleaning with deionized water and ethanol to obtain SiO2@ Ag composite material. The grain diameter of the Ag particles is 5-10 nm.
And step six, taking 0.3g of the composite material, putting into 2.5ml of DMF solution, and performing ultrasonic dispersion. Then 0.2g PAN was added and stirred at 60 ℃ for 12h to obtain a spinning precursor solution.
And seventhly, performing electrostatic spinning by using the spinning precursor solution prepared in the sixth step to obtain the fiber yarn. The spinning parameters are as follows: the flow rate is 1ml/h, and the spinning voltage is 15 kV.
Step eight, collecting the fiber filaments, calcining for 3 hours at 750 ℃ in Ar atmosphere to prepare C @ SiO2@ Ag one-dimensional composite material;
and step nine, adding the one-dimensional material into 50ml of 5mol/l KOH solution, and preserving the heat at 70 ℃ for 48 hours to obtain a third mixed solution.
Step ten, centrifuging and cleaning the third mixed solution, and adding deionized water to prepare a fourth mixed solution with the viscosity of 4000 mPa.s.
And step eleven, coating the fourth mixed solution prepared in the step eleven on a Cu foil in a coating thickness of 400 microns, quickly immersing in liquid nitrogen, freeze-drying for 24 hours, and tearing off the Cu foil by using tweezers to obtain the final negative electrode material. SEM test results show that the honeycomb-shaped pore size of the two-dimensional material is about 3 μm.
Example 3
A preparation method of a high-performance anode material comprises the following steps:
step one, preparing 0.1mol/L SnCl250ml of an aqueous solution, 0.01mol of SiO are added2And (4) dispersing the nano powder for 30min by ultrasonic to prepare a first mixed solution. The particle size of the selected silicon dioxide is 200 nm;
step two, centrifuging and filtering the first mixed solution, and washing the mixture for a plurality of times by using distilled water and ethanol to obtain Sn2+Sensitized SiO2Nanoparticles, centrifuge speed 6000 rpm.
Step three, sensitizing the SiO2Putting the nano particles into 10ml of deionized water, and performing ultrasonic dispersion for 30min to prepare a second mixed solution;
step four, mixing 0.003molAgNO3Adding into 0.5ml deionized water, dropwise adding 2.5ml ammonia water (ammonia water concentration of 6 wt%), ultrasonic dispersing for 30min to obtain ammoniated AgNO3And (3) solution. Wherein AgNO3The concentration is 1 mol/L.
Step five, adding the second mixed solution prepared in the step three into the ammoniated AgNO prepared in the step four3Stirring in the solution at room temperature for 1h, centrifuging, filtering, and repeatedly washing with deionized water and ethanol to obtain SiO2@ Ag composite material. The grain diameter of the Ag particles is 5-10 nm.
And step six, taking 0.3g of the composite material, putting into 2.5ml of DMF solution, and performing ultrasonic dispersion. Then 0.2g PAN was added and stirred at 60 ℃ for 12h to prepare a spinning precursor solution.
And seventhly, performing electrostatic spinning by using the spinning precursor solution prepared in the sixth step to obtain the fiber yarn. The spinning parameters are as follows: the flow rate is 1ml/h, and the spinning voltage is 15 kV.
Step eight, collecting the fiber filaments, calcining for 3 hours at 750 ℃ in Ar atmosphere to prepare C @ SiO2@ Ag one-dimensional composite material;
and step nine, adding the one-dimensional material into 50ml of 5mol/l KOH solution, and preserving the heat at 70 ℃ for 48 hours to obtain a third mixed solution.
And step ten, centrifuging and cleaning the third mixed solution, and adding deionized water to prepare a fourth mixed solution with the viscosity of 2000 mPa.s.
And step eleven, coating the fourth mixed solution prepared in the step eleven on a Cu foil in a coating thickness of 400 microns, quickly immersing in liquid nitrogen, freeze-drying for 24 hours, and tearing off the Cu foil by using tweezers to obtain the final negative electrode material. SEM test results show that the honeycomb-shaped pore size of the two-dimensional material is about 5 μm.
Comparative example 1
Step nine was not performed, and the other preparation processes were the same as in example 1.
Namely, the steps I to eight are the same as the step 1, and C @ SiO is prepared2And after the @ Ag one-dimensional composite material is obtained, directly adding the composite material into deionized water to prepare a fourth mixed solution with higher viscosity. And then the anode material is coated on a Cu foil by a doctor blade and is quickly immersed in liquid nitrogen for freeze drying to obtain the anode material.
Comparative example 2
The procedure one to ten is the same as in example 1.
And step eleven, coating the fourth mixed solution prepared in the step eleven on a Cu foil in a coating thickness of 400 microns, quickly placing the Cu foil in a vacuum drying box, and performing vacuum drying at 80 ℃ for 24 hours to obtain the final negative electrode material.
Comparative example 3
And selecting a pure lithium sheet with the same thickness as the negative pole piece.
Test example
The negative pole pieces prepared in the above examples and comparative examples were cut into disks with a diameter of 14mm as negative pole pieces, and lithium iron phosphate pole pieces (with an areal density of 4 mg/cm) were used2The compacted density is 2.1g/cm3LFP: SP: the mass ratio of PVDF is 8: 1: 1) and cutting into a circular sheet with the diameter of 12mm as the anode sheet. Polypropylene Celgard2500 is used as a diaphragm, lithium hexafluorophosphate solution (the concentration of lithium hexafluorophosphate is 1mol/L, the volume ratio of solvents DMC, EMC and EC is 1: 1: 1) is used as electrolyte, and the electrolyte is assembled into a CR2025 type button cell in a glove box. The concentration of water and oxygen in the glove box is less than or equal to 0.1 ppm.
The assembled button cell was subjected to constant current charge and discharge testing using a blue charge and discharge testing system (CT2001A), and the obtained electrochemical test data are shown in table 1.
TABLE 1
The test results in table 1 show that the negative electrode plate prepared in the embodiments 1 to 3 by using the technical scheme of the present invention has excellent electrochemical properties. Due to the unique cellular porous and hollow carbon sphere inner wall anchoring nano silver particle structure, the ordered deposition of lithium is realized in the battery charging and discharging process, and the formation and growth of lithium dendrites are inhibited. The battery prepared by the cathode has outstanding electrochemical performance: the 10C high-rate discharge can be realized, the 5C charge-discharge cycle life reaches more than 1000 times, and the 1000 th cycle coulombic efficiency reaches more than 95%.
While the negative electrode of comparative example 1 was prepared without SiO2A step of being etched, finallyThe obtained cathode material has the component of C @ SiO2@ Ag. Although a honeycomb porous structure is obtained, the primary particles are in a solid sphere structure, but the inner walls of the hollow carbon spheres are anchored with a nano silver particle structure. The performance effects expected from the present invention cannot be achieved, even lower than that of a pure lithium negative electrode.
The preparation process of the negative electrode of the comparative example 2 does not implement the freeze drying step, and the honeycomb porous structure cannot be obtained, but the unique hollow carbon sphere containing nano silver particle structure still plays a great role in inducing ordered deposition of lithium and inhibiting growth of lithium dendrites, so that the final negative electrode still has high electrochemical performance.
Comparative example 3 using pure metallic lithium as the negative electrode revealed common problems of lithium metal batteries, such as uneven deposition of lithium, irreversible loss of active lithium and electrolyte, etc., which are manifested as poor electrochemical performance.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (10)
1. The high-performance lithium ion battery cathode material is characterized in that the cathode material is a two-dimensional material formed by interweaving and stacking one-dimensional nanowires and has a porous structure;
the one-dimensional nanowires are formed by arranging spherical particles in a chain shape, the spherical particles are hollow nanospheres and comprise a shell and metal particles deposited on the inner wall of the shell, and the shell is made of carbon.
2. The negative electrode material of claim 1, wherein the two-dimensional material has a pore size of 1-10 μm and a specific surface area of 20-100 m2/g；
And/or the length of the one-dimensional nanowire is 10-30 mu m, and the radius of the one-dimensional nanowire is 100-300 nm;
and/or the shell material is amorphous carbon, and the material of the metal particles is selected from any one of Ag, Au, Zn and Mg;
and/or the size of the spherical particles is 100-300 nm, the thickness of the shell is 1-10 nm, and the size of the metal particles is 5-15 nm.
3. The method for preparing the anode material according to claim 1, comprising the steps of:
step one, SiO2Placing the nano powder in SnCl2In the aqueous solution, a first mixed solution is prepared by ultrasonic dispersion;
step two, sequentially centrifuging, filtering and cleaning the first mixed solution prepared in the step one to obtain Sn2+Sensitized SiO2A nanoparticle;
step three, Sn2+Sensitized SiO2Adding the nano particles into deionized water, and performing ultrasonic dispersion to prepare a second mixed solution;
step four, AgNO is added3Placing in deionized water, dropwise adding ammonia water, and ultrasonically dispersing to obtain ammoniated AgNO3A solution;
step five, adding the ammoniated AgNO prepared in the step four into the second mixed solution prepared in the step three3The solution is stirred, centrifuged, filtered and washed in sequence at room temperature to prepare SiO2@ Ag composite material;
step six, taking the SiO2The @ Ag composite material is put into a solution with DMF as a solvent and PAN as a solute and mixed to prepare a spinning precursor solution;
step seven, performing electrostatic spinning by using the spinning precursor solution prepared in the step six to obtain fiber yarns;
step eight, collecting the fiber filaments prepared in the step seven, and calcining the fiber filaments in an inert atmosphere to prepare C @ SiO2@ Ag nanowires;
step nine, adding the nanowires prepared in the step eight into a KOH or NaOH aqueous solution, and standing to obtain a third mixed solution;
step ten, after centrifuging and cleaning the third mixed solution, adding deionized water to prepare a fourth mixed solution;
and step eleven, blade-coating the fourth mixed solution on the surface of a carrier, freeze-drying to form a slice containing the high-performance negative electrode material, peeling the slice from the surface of the carrier, and cutting to obtain the negative electrode plate of the lithium ion battery.
4. The method of claim 3, wherein in step one, the SiO is2The particle size of the nano powder is 100-300 nm;
and/or, the SiO2Nano powder and SnCl2The molar ratio of (1-5) to (1).
5. The method of claim 3, wherein in step four, the AgNO is3The molar ratio of the ammonia to the ammonia is (0.5-1): 1, the concentration of ammonia water is 1-3 mol/L, and AgNO is obtained after ammoniation3The concentration is 0.5-2 mol/L.
6. The method of claim 3, wherein in step six, the SiO2The mass ratio of the @ Ag composite material to the PAN is (1-3): 1, and the mass ratio of the DMF to the PAN is (10-15): 1;
and/or stirring for 10-15 h at the temperature of 55-65 ℃.
7. The method according to claim 3, wherein in the eighth step, the inert atmosphere is nitrogen or argon, and the calcination temperature is 600-850 ℃ and the calcination time is 2-4 h.
8. The method according to claim 3, wherein in the ninth step, the molar concentration of the KOH or NaOH aqueous solution is 3-8 mol/L, the standing temperature is 65-75 ℃, and the standing time is 46-60 h.
9. The method according to claim 3, wherein in the tenth step, the viscosity of the fourth mixed solution is 1000 to 7000 mPa.s.
10. The method according to claim 3, characterized in that in the eleventh step, the temperature of the freeze drying is-40 to-20 ℃ and the time is 24 to 36 hours.
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