CN113428866A - Wool-line-ball-shaped SiOx/C and preparation method and application thereof - Google Patents

Wool-line-ball-shaped SiOx/C and preparation method and application thereof Download PDF

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CN113428866A
CN113428866A CN202110695238.0A CN202110695238A CN113428866A CN 113428866 A CN113428866 A CN 113428866A CN 202110695238 A CN202110695238 A CN 202110695238A CN 113428866 A CN113428866 A CN 113428866A
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sio
wool
ammonia water
ball
solution
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CN113428866B (en
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王海龙
何苗
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Ningxia University
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Abstract

The invention relates to the technical field of cathode materials, in particular to a wool-ball-shaped SiOxThe preparation method provided by the invention comprises the following steps: mixing ethyl orthosilicate, first ethanol and water to obtain a silicon source solution; mixing ammonia water and second ethanol to obtain ammonia water mixed solution; mixing the silicon source solution and the ammonia water mixed solution, mixing the mixed solution with a citric acid solution under a reflux condition, and adding ethylene glycol to obtain a colloid; drying, presintering and roasting the colloid in sequence to obtain the wool-ball-shaped SiOxC; the knitting wool is in a ball shapeSiOxThe value range of x in the/C is 1-2. SiO prepared by the preparation methodxthe/C has higher conductivity, tap density and energy density.

Description

Wool-line-ball-shaped SiOx/C and preparation method and application thereof
Technical Field
The invention relates to the technical field of cathode materials, in particular to a wool-ball-shaped SiOxA preparation method and application thereof.
Background
The silicon-based anode material comprises Si and SiOx(x is 0-2, and x is not equal to 0) is far higher than that of a graphite cathode materialThe specific capacity of lithium storage. SiO 2xThe conductivity is extremely poor, the carbon composite nano-SiO with high conductivity is easy to break due to severe volume change in the charging and discharging processesxTo improve conductivity, buffer volume changes and maintain particle stability. Carbon composite nanoscale SiO commonly preparedxPrimary particles dispersed in each other, or sparse nano SiOxThe dispersion on the carbon matrix can improve the conductivity and effectively buffer the volume change, but the tap density of the entire material is small and the energy density is low.
Meanwhile, it is desired in industrial applications to produce micron-sized carbon-coated secondary particles formed by aggregation of a large number of primary nanoparticles. However, in the existing process of preparing secondary particles, primary particles are easily combined together to form micron-sized large particles due to high temperature, the conductivity and stability are deteriorated, and the composite conductive carbon can only cover the surfaces of the secondary particles, so that the conductivity of the primary particles in the secondary particles cannot be improved.
Disclosure of Invention
The invention aims to provide a wool-like bulk SiOx/C, preparation method and application thereof, and SiO prepared by using preparation methodxthe/C has higher conductivity, tap density and energy density.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a wool-like bulk SiOxThe preparation method of the/C comprises the following steps:
mixing ethyl orthosilicate, first ethanol and water to obtain a silicon source solution;
mixing ammonia water and second ethanol to obtain ammonia water mixed solution;
mixing the silicon source solution and the ammonia water mixed solution, mixing the mixed solution with a citric acid solution under a reflux condition, and adding ethylene glycol to obtain a colloid;
drying, presintering and roasting the colloid in sequence to obtain the wool-ball-shaped SiOx/C；
The wool ball SiOxThe value range of x in the/C is 1-2.
Preferably, the volume ratio of the ethyl orthosilicate to the first ethanol to the water is (1-6): (8-16): 1.
preferably, the mass concentration of the ammonia water is 25-28%;
the volume ratio of the ammonia water to the second ethanol is 1: (1-5).
Preferably, the volume ratio of the silicon source solution to the ammonia water mixed solution is (7-8): 1.
preferably, the concentration of the citric acid solution is 0.1-1 g/mL;
the volume ratio of the total volume of the mixed solution of the silicon source solution and the ammonia water to the citric acid solution is (4-6): 2.
preferably, the reflux temperature is 40-80 ℃, and the time is 2-18 h;
the volume ratio of the mixed solution obtained after refluxing to the ethylene glycol is 42: (0.5-2).
Preferably, the pre-sintering temperature is 300-400 ℃, and the time is 2-6 h.
Preferably, the calcination is carried out in an inert atmosphere or under vacuum conditions;
the roasting temperature is 700-1100 ℃, and the roasting time is 2-6 h.
The invention also provides the wool-like bulk SiO prepared by the preparation method of the technical schemexa/C comprising a three-dimensionally crosslinked hairline ball structure composed of a carbon material and SiO wound in the hairline ball structurex；
The value range of x is 1-2.
The invention also provides the knitting wool bulk SiO in the technical schemexThe application of the/C as a negative electrode material in a battery.
The invention provides a wool-like bulk SiOxThe preparation method of the/C comprises the following steps: mixing ethyl orthosilicate, first ethanol and water to obtain a silicon source solution; mixing ammonia water and second ethanol to obtain ammonia water mixed solution; mixing the silicon source solution and the ammonia water mixed solution, mixing the mixed solution with a citric acid solution under a reflux condition, and adding ethylene glycol to obtain a colloid; drying the colloid in sequencePre-burning and roasting to obtain the wool bulk SiOxC; the wool ball SiOxThe value range of x in the/C is 1-2.
The preparation method of the invention utilizes the cross-linking of ethylene glycol and citric acid in the hydrolysis solution of ethyl orthosilicate to form a three-dimensional space in the solution and form staggered surrounding to a silicon source, after colloid is formed, the carbonization of a cross-linked structure can be realized by pre-burning, and the formation of nano SiO in the cross-linked structure can be realized by roastingxFinally, SiO is addedxTightly wound in a three-dimensionally cross-linked wool coil structure composed of a carbon material. While the carbon material in the shape of a round wool is tightly wound with SiOxProviding a good conductive contact and thus being able to increase its specific capacity (i.e. energy density). At the same time, the carbon material in the shape of round wool lines buffers SiOxThe drastic volume change in the charging and discharging process, even under the condition of large specific capacity charging and discharging, leads to SiOxThe fragments are still tightly wound by the wool coil structure to keep conductive contact, and the activity cannot be lost, so that the high-specific capacity performance can be kept in long-period circulation. And the wool yarn coil structure has excellent elasticity, can quickly buffer the stress strain in the charge-discharge process, and avoids additional lithium ion activity loss caused by repeatedly forming new SEI after an SEI film on the surface of the negative electrode is subjected to stress crushing, so that extremely high coulombic efficiency can be quickly achieved and stably maintained, and the electrochemical stability of the composite material is improved.
Compared with the prior art, the invention has the following beneficial effects:
1) the wool-like bulk SiO prepared by the preparation method of the inventionxThe carbon material in the form of wool in the/C is bonded to SiO from the surface to the inside of the secondary particlesxThe primary particles are closely entangled and contacted, so that the conductivity of the secondary particles can be obviously improved;
2) the wool-like bulk SiO prepared by the preparation method of the inventionxThe C wool coil structure can effectively buffer stress strain caused by severe volume change, namely even if severe volume change can cause sequential particle crushing, crushed fragments are still embedded in the carbon wool coil to keep conductive contact and activity, so thatThereby obviously improving the SiOxThe charge and discharge stability of (1);
3) the wool-like bulk SiO prepared by the preparation method of the inventionxSiO in/CxThe primary particles are mutually independent, and the electrochemical reaction activity is good;
4) the wool-like bulk SiO prepared by the preparation method of the inventionxThe tap density and energy density of the/C are obviously improved;
5) the wool-like bulk SiO prepared by the preparation method of the inventionxThe second charge and discharge capacity of the/C is high, the coulombic efficiency is high, and the electrochemical performance is stable.
Drawings
FIG. 1 is a schematic representation of the hairline-shaped SiO solid particles described in example 1xSEM image at small magnification;
FIG. 2 is a schematic view of the hairline-shaped SiO solid particles of example 1xSEM image at large magnification;
FIG. 3 shows a hairline-shaped SiO solid prepared in example 1xC and carbon-coated nano SiO prepared in comparative example 1xAt 0.1 A.g-1The first constant current charge-discharge curve under the current density of (a);
FIG. 4 shows a hairline-shaped SiO solid prepared in example 1xC and carbon-coated nano SiO prepared in comparative example 1xAt 1 A.g-1A 500-cycle charge-discharge performance map at a current density of (a);
FIG. 5 shows the hairline-shaped SiO solid particles of example 2xSEM image at small magnification;
FIG. 6 shows a hairline-shaped SiO solid layer obtained in example 2xSEM image at large magnification;
FIG. 7 shows the bulk of the hairline SiO prepared in example 2xC is in the range of 1 A.g-1A cyclic charge-discharge performance map at a current density of (a);
FIG. 8 is a schematic view of the hairline-shaped SiO solid particles of example 3xSEM image at small magnification;
FIG. 9 is a schematic representation of the hairline-shaped SiO solid particles of example 3xSEM image at large magnification;
FIG. 10 shows the wool obtained in example 3Wire-ball shaped SiOxC is in the range of 1 A.g-1A cyclic charge-discharge performance map at a current density of (a);
FIG. 11 shows carbon-coated nano SiO 2 as described in comparative example 1xSEM images at small magnification;
FIG. 12 shows carbon-coated nano SiO 2 as in comparative example 1xSEM images at large magnification;
FIG. 13 carbon-coated Nano SiO as described in comparative example 2xSEM picture of (1);
FIG. 14 carbon-coated Nano SiO comparative example 2xA TEM image of (a).
Detailed Description
The invention provides a wool-like bulk SiOxThe preparation method of the/C comprises the following steps:
mixing ethyl orthosilicate, first ethanol and water to obtain a silicon source solution;
mixing ammonia water and second ethanol to obtain ammonia water mixed solution;
mixing the silicon source solution and the ammonia water mixed solution, mixing the mixed solution with a citric acid solution under a reflux condition, and adding ethylene glycol to obtain a colloid;
drying, presintering and roasting the colloid in sequence to obtain the wool-ball-shaped SiOx/C；
The wool ball SiOxThe value range of x in the/C is 1-2.
In the present invention, all the starting materials for the preparation are commercially available products known to those skilled in the art unless otherwise specified.
The method comprises the step of mixing tetraethoxysilane, first ethanol and water to obtain a silicon source solution.
In the invention, the volume ratio of the ethyl orthosilicate, the first ethanol and the water is preferably (1-6): (8-16): 1, more preferably (2-5): (10-15): 1, most preferably (3-4): (12-13): 1.
in the present invention, the mixing is preferably performed under stirring, and the stirring time is preferably 1 h; the stirring speed is not limited in any way, and the tetraethoxysilane, the ethanol and the water can be fully and uniformly mixed by adopting the rotating speed which is well known by a person skilled in the art under the stirring time.
In the invention, the ethyl orthosilicate is used for preparing SiOxProviding a silicon source; the first ethanol is used for dissolving the ethyl orthosilicate and forming uniform mixed liquid with water.
The preparation method also comprises the step of mixing the ammonia water and the second ethanol to obtain an ammonia water mixed solution.
In the present invention, the mass concentration of the ammonia water is preferably 25% to 28%, more preferably 26% to 27%.
In the present invention, the volume ratio of the ammonia water to the second ethanol is preferably 1: (1-5), more preferably 1: (2-4), most preferably 1: (2.5-3.5).
In the present invention, the mixing is preferably performed under stirring, and the stirring time is preferably 1 h; the stirring speed is not limited in any way, and the ammonia water and the ethanol can be fully mixed by adopting the rotating speed which is well known to a person skilled in the art under the stirring time.
In the invention, the function of the ammonia water is to promote the condensation polymerization reaction after the hydrolysis of the subsequent tetraethoxysilane to generate a- [ Si-O ] -group; the function of the second ethanol is to enable ammonia water to be mutually soluble with ethyl orthosilicate.
After a silicon source solution and ammonia water mixed solution is obtained, the silicon source solution and the ammonia water mixed solution are mixed, mixed with a citric acid solution under the condition of reflux, and added with glycol to obtain colloid
In the present invention, the volume ratio of the silicon source solution to the ammonia water mixed solution is preferably (7 to 8): 1, more preferably (7.2 to 7.8): 1, most preferably (7.4-7.6): 1.
in the invention, the mixing is preferably carried out under the condition of stirring, and the stirring time is preferably 1-6 h, more preferably 2-5 h, and most preferably 3-4 h. The rotation speed of the stirring is not limited in any way in the present invention, and may be any rotation speed known to those skilled in the art.
In the present invention, the mixing of the silicon source solution and the ammonia-water mixed solution is preferably performed by introducing the ammonia-water mixed solution into the silicon source solution; the drainage speed is preferably 1-100 mL/min, and more preferably 10-60 mL/min.
In the invention, in the mixing process, the silicon source solution and the ammonia water mixed solution are subjected to hydrolysis polycondensation reaction to generate a- [ Si-O ] -group.
In the invention, the concentration of the citric acid solution is preferably 0.1-1 g/mL, more preferably 0.3-0.8 g/mL, and most preferably 0.4-0.6 g/mL.
In the present invention, the ratio of the total volume of the silicon source solution and the ammonia water mixed solution to the volume of the citric acid solution is preferably (4 to 6): 2, more preferably (4.5 to 5.5): 2, most preferably (4.8-5.2): 2.
in the invention, the reflux temperature is preferably 40-80 ℃, more preferably 50-70 ℃, and most preferably 55-65 ℃; the time is preferably 2 to 18 hours, more preferably 5 to 13 hours, and most preferably 8 to 10 hours.
In the present invention, the reflux is preferably carried out under stirring, and the rotation speed of the stirring is preferably 600 r/min.
In the present invention, the citric acid solution is a carbon source.
In the present invention, the volume ratio of the mixed solution obtained after the reflux to ethylene glycol is preferably 42: (0.5-2), more preferably 42: (0.8 to 1.6), most preferably 42: (1.0-1.3).
In the present invention, the mixing of the mixed solution obtained after the flowing and the ethylene glycol is preferably performed under stirring; the stirring temperature is preferably 40-80 ℃, more preferably 50-70 ℃, and most preferably 55-65 ℃; the time is preferably 4 to 8 hours, more preferably 5 to 6 hours, and most preferably 5.3 to 5.6 hours; the rotation speed of the stirring is preferably 600 r/min.
After the colloid is obtained, the colloid is sequentially dried, presintered and roasted to obtain the wool-shaped bulk SiOxC; the wool ball SiOxThe value range of x in the/C is 1-2.
In the invention, the drying temperature is preferably 120 ℃, the drying time is preferably 4-24 h, more preferably 8-20 h, and most preferably 13-16 h.
After the drying is completed, the invention also preferably comprises ball milling; in the invention, the ball milling time is preferably 1-8 h, and more preferably 3-6 h; the rotation speed of the ball mill is not limited in any way, and can be determined by the rotation speed well known to those skilled in the art.
In the present invention, the pre-firing is preferably performed in an air atmosphere; the pre-sintering temperature is preferably 300-400 ℃, more preferably 320-380 ℃, and most preferably 340-360 ℃; the time is preferably 2 to 6 hours, and more preferably 3 to 4 hours.
In the invention, the pre-burning can remove moisture in a clean system, and can also lead citric acid to be pyrolyzed to form carbon and form a wool dough-like structure.
In the present invention, the calcination is preferably carried out in an inert atmosphere or under vacuum conditions; the gas of the inert atmosphere is preferably argon or nitrogen. In the invention, the roasting temperature is preferably 700-1100 ℃, more preferably 800-1000 ℃, and most preferably 850-950 ℃; the time is preferably 2 to 6 hours, and more preferably 3 to 5 hours.
In the present invention, the calcination atmosphere is defined as a vacuum atmosphere or an inert atmosphere so that the SiO originally becomes very smallxThe particles are polymerized and grown into particles of 100-300 nm, and simultaneously, the phenomenon that the wool-like carbon material is burnt in an oxygen-containing atmosphere is prevented.
The invention also provides the wool-like bulk SiO prepared by the preparation method of the technical schemexa/C comprising a three-dimensionally crosslinked hairline ball structure composed of a carbon material and SiO wound in the hairline ball structurex；
The value range of x is 1-2.
In the present invention, the SiOxThe particle size of (A) is preferably 100 to 300 nm. In the present invention, the carbon material and SiOxThe mass ratio of (2) to (5): (8-5), more preferably (2.5-3.5): (7.5 to 6.5), and most preferably 3: 7.
The invention also provides the knitting wool bulk SiO in the technical schemexAs negative electrode materialApplication in batteries. The method of the present invention is not particularly limited, and the method may be performed by a method known to those skilled in the art.
The following examples are provided to illustrate bulk SiO of wool according to the present inventionxThe details of the process and the use of the/C are given, but they should not be construed as limiting the scope of the invention.
Example 1
Mixing 13.5mL of ethanol, 1mL of water and 2.6mL of ethyl orthosilicate, and stirring for 1h to obtain an ethyl orthosilicate solution;
mixing 1mL of ammonia water with the mass concentration of 27% and 4.7mL of ethanol, and stirring for 1h to obtain an ammonia water mixed solution;
introducing 7.77mL of the ammonia water mixed solution into 1mL of the orthosilicic acid solution, stirring for 3h, adding 3.508mL of citric acid solution with the concentration of 0.288g/mL, stirring and refluxing at the temperature of 60 ℃ (the stirring speed is 600r/min) for 12h, adding 0.29mL of ethylene glycol, and stirring and refluxing at the temperature of 60 ℃ (the stirring speed is 600r/min) for 4h to obtain a colloid;
drying the colloid at 120 ℃ for 12h, ball-milling for 4h, presintering in air at 350 ℃ for 4h, and roasting at 900 ℃ in nitrogen atmosphere for 4h to obtain wool-ball-shaped SiOx/C(SiOxAnd C in a mass ratio of 7: 3);
FIG. 1 shows the bulk SiO of the woolxSEM image at small magnification; FIG. 2 shows the bulk SiO of the knitting woolxSEM image of/C under large magnification, as can be seen from FIG. 1, the hairline-like SiOxThe particle size of the/C is 4-8 mu m; as can be seen from FIG. 2, the wool-like bulk SiOxC, winding nano-hair-wire-bulk SiO by hair-wire-shaped carbon with visible bending insidexAnd (4) forming a wool-ball-like structure.
Example 2
Mixing 15mL of ethanol, 1mL of water and 3mL of ethyl orthosilicate, and stirring for 1h to obtain an ethyl orthosilicate solution;
mixing 1mL of ammonia water with the mass concentration of 27% and 4.7mL of ethanol, and stirring for 1h to obtain an ammonia water mixed solution;
draining 8mL of the ammonia water mixed solution into 1mL of the orthosilicic acid solution, stirring for 3h, adding 4mL of citric acid solution with the concentration of 0.4g/mL, stirring and refluxing at the temperature of 60 ℃ (the stirring rotating speed is 600r/min) for 12h, adding 0.31mL of glycol, stirring and refluxing at the temperature of 60 ℃ (the stirring rotating speed is 600r/min) for 4h, and obtaining colloid;
drying the colloid at 120 ℃ for 12h, ball-milling for 4h, presintering in air at 350 ℃ for 4h, and roasting at 900 ℃ in nitrogen atmosphere for 4h to obtain wool-ball-shaped SiOx/C(SiOxAnd C in a mass ratio of 7.5: 2.5);
FIG. 5 shows the hairline bulk SiOxSEM image at small magnification; FIG. 6 shows the hairline bulk SiOxSEM image of/C at Large magnification, from FIG. 5, it can be seen that the hairline-like SiOxThe particle size of the/C is 3-8 mu m; as can be seen from FIG. 6, the hairline-like bulk SiOxC, winding nano-hair-wire-bulk SiO by hair-wire-shaped carbon with visible bending insidexAnd (4) forming a wool-ball-like structure.
Example 3
Mixing 12mL of ethanol, 1mL of water and 2mL of tetraethoxysilane, and stirring for 1h to obtain a tetraethoxysilane solution;
mixing 1mL of ammonia water with the mass concentration of 27% with 3mL of ethanol, and stirring for 1h to obtain an ammonia water mixed solution;
draining 7mL of the ammonia water mixed solution into 1mL of the orthosilicic acid solution, stirring for 3h, adding 2.91mL of citric acid solution with the concentration of 0.18g/mL, stirring and refluxing at the temperature of 60 ℃ (the stirring rotating speed is 600r/min) for 12h, adding 0.13mL of ethylene glycol, stirring and refluxing at the temperature of 60 ℃ (the stirring rotating speed is 600r/min) for 4h, and thus obtaining colloid;
drying the colloid at 120 ℃ for 12h, ball-milling for 4h, presintering in air at 350 ℃ for 4h, and roasting at 900 ℃ in nitrogen atmosphere for 4h to obtain wool-ball-shaped SiOx/C(SiOxAnd C in a mass ratio of 6.5: 3.5);
FIG. 8 shows the hairline bulk SiOxSEM image at small magnification; FIG. 9 shows the hairline bulk SiOxSEM image of/C at Large magnification, from FIG. 8, it can be seen that the hairline-like SiOxThe particle diameter of C is 3-9Mu m; as can be seen from FIG. 9, the hairline-like bulk SiOxC, winding nano-hair-wire-bulk SiO by hair-wire-shaped carbon with visible bending insidexAnd (4) forming a wool-ball-like structure.
Comparative example 1
Mixing 13.5mL of ethanol, 1mL of water and 2.6mL of ethyl orthosilicate, and stirring for 1h to obtain an ethyl orthosilicate solution;
mixing 1mL of ammonia water with the mass concentration of 27% and 4.7mL of ethanol, and stirring for 1h to obtain an ammonia water mixed solution;
introducing 7.77mL of the ammonia water mixed solution into 1mL of the orthosilicic acid solution, stirring for 3h, adding 3.508mL of citric acid solution with the concentration of 0.288g/mL, stirring and refluxing at the temperature of 60 ℃ (the stirring speed is 600r/min) for 12h, and stirring and refluxing at the temperature of 60 ℃ (the stirring speed is 600r/min) for 4h to obtain a colloid;
drying the colloid at 120 ℃ for 12h, ball-milling for 4h, presintering in air at 350 ℃ for 4h, and roasting at 900 ℃ in nitrogen atmosphere for 4h to obtain carbon-coated nano SiOx(as SiO)x/C，SiOxAnd C in a mass ratio of 7: 3);
FIG. 11 shows the carbon-coated nano SiOxSEM images at small magnification; FIG. 12 shows the carbon-coated nano SiOxSEM image under large magnification, as can be seen from FIG. 11, the carbon-coated nano SiOxThe particle size of (A) is 5-10 μm; as can be seen from FIG. 12, the carbon-coated nano SiOxThe cross section shows that it is a large-sized primary particle, there is no carbon material inside, and the coated carbon exists only on the surface of the particle.
Comparative example 2
Mixing 15mL of ethanol and 1.1mL of tetraethoxysilane, and stirring for 1h to obtain a tetraethoxysilane solution;
mixing 9.5mL of 27% ammonia water, 22mL of water and 1.75mL of ethanol, and stirring for 1h to obtain an ammonia water mixed solution;
introducing 33.25mL of the ammonia water mixed solution into 16.1mL of the orthosilicic acid solution, stirring for 3h, adding 10mL of citric acid solution with the concentration of 0.096g/mL, stirring and refluxing at the temperature of 60 ℃ (the rotation speed of reflux stirring is 300r/min) for 12h, adding 0.29mL of ethylene glycol, and continuously stirring at the temperature of 60 ℃ (300r/min) for 4h to form a colloid;
drying the colloid at 120 ℃ for 12h, ball-milling for 4h, presintering in air at 350 ℃ for 4h, and roasting at 900 ℃ in nitrogen atmosphere for 4h to obtain carbon-coated nano SiOx(as SiO)x/C，SiOxAnd C in a mass ratio of 7: 3);
FIG. 13 shows the carbon-coated nano SiOxSEM picture of (1); FIG. 14 shows the carbon-coated nano SiOxFrom FIG. 13, the carbon-coated nano SiOxThe grain diameter of the particles is more than or equal to 10 mu m; as can be seen from FIG. 14, the interior of the secondary particles was coated with a large amount of nano-sized carbon to form spherical SiOxAggregated and no wool-like carbon appears.
Test example
The hairline-shaped bulk SiO prepared in examples 1 to 3xC and carbon-coated nano SiO prepared in comparative examples 1-2xCarrying out electrochemical performance test:
the floss ball-shaped SiO prepared in the example 1-3 was mixed according to the weight ratio of 7:1.5:1.5xC and carbon-coated nano SiO prepared in comparative examples 1-2xRespectively mixing the conductive carbon black and sodium alginate to prepare a working electrode, assembling a CR2032 button half cell by taking a metal lithium sheet as a counter electrode, and testing at room temperature;
wherein, FIG. 3 shows the bulk SiO of the knitting wool prepared in example 1xC and carbon-coated nano SiO prepared in comparative example 1xAt 0.1 A.g-1The first constant current charge and discharge curve at the current density of (wherein the assembled CR2032 button half-cell was activated for 24 hours at a lithium voltage of 0.27V for the CR before the first charge and discharge) is shown in fig. 3, where the SiO is prepared in the form of a wool ball as in example 1xAt 0.1 A.g of C-1Has a specific capacity of 1297mA · h · g under a current density of-1(ii) a And the carbon-coated nano SiO prepared in comparative example 1xAt 0.1 A.g-1The specific capacity of the specific resistance is only 900 mA.h.g under the current density-1；
FIG. 4 shows a hairline-shaped SiO solid prepared in example 1xC and carbon-coated nano SiO prepared in comparative example 1xAt 1 A.g-1The 500-cycle charge/discharge performance chart at the current density of (1) is shown in FIG. 4, and it is understood that the hairline-like bulk SiO of example 1xThe maximum/C can provide 709mAh-1The coulomb efficiency is rapidly improved to 99.9% after circulating for 20 weeks, and then the specific capacity is kept close to 100%; comparative example 1 preparation of carbon-coated nano SiOxCan only provide 380mA · h · g at the highest-1The specific capacity is far lower than that of the embodiment 1, the coulombic efficiency is below 98 percent for a long time, the coulombic efficiency reaches 98 percent after 51 weeks of circulation, the coulombic efficiency reaches 99 percent after 314 weeks of circulation, and then the coulombic efficiency fluctuates between 98 percent and 99 percent; the description is given of the fluffy-shaped SiO solid prepared in example 1xThe specific capacity of the/C can be larger under high rate, and the coulombic efficiency close to 100% can be more quickly achieved and kept stable;
FIG. 7 shows the bulk of the hairline SiO prepared in example 2xC is in the range of 1 A.g-1FIG. 7 shows the cyclic charge/discharge performance at current density of (A), in which the SiO powder prepared in example 2 is in the form of a wool ballxThe maximum specific discharge capacity of the catalyst/C is 530 mA.h.g-1The coulombic efficiency can reach 99% after circulating for 20 weeks, and the efficiency is kept close to 100%;
FIG. 10 shows a hairline-like bulk SiO prepared in example 3xC is in the range of 1 A.g-1FIG. 8 shows the cyclic charge/discharge performance at current density of (A), in which the SiO solid particles prepared in example 3 are in the form of matted agglomeratesxThe maximum specific discharge capacity of the catalyst/C is 740 mA.h.g-1Coulombic efficiency reached 99% after 25 weeks of cycling and remained close to 100% in subsequent cycles.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. Wool-ball-shaped SiOxThe preparation method of the/C is characterized by comprising the following steps:
mixing ethyl orthosilicate, first ethanol and water to obtain a silicon source solution;
mixing ammonia water and second ethanol to obtain ammonia water mixed solution;
mixing the silicon source solution and the ammonia water mixed solution, mixing the mixed solution with a citric acid solution under a reflux condition, and adding ethylene glycol to obtain a colloid;
drying, presintering and roasting the colloid in sequence to obtain the wool-ball-shaped SiOx/C；
The wool ball SiOxThe value range of x in the/C is 1-2.
2. The preparation method according to claim 1, wherein the volume ratio of the ethyl orthosilicate, the first ethanol and the water is (1-6): (8-16): 1.
3. the preparation method according to claim 1, wherein the mass concentration of the ammonia water is 25% to 28%;
the volume ratio of the ammonia water to the second ethanol is 1: (1-5).
4. The method according to claim 1, 2 or 3, wherein the volume ratio of the silicon source solution to the ammonia-water mixed solution is (7-8): 1.
5. the method according to claim 4, wherein the citric acid solution has a concentration of 0.1 to 1 g/mL;
the volume ratio of the total volume of the mixed solution of the silicon source solution and the ammonia water to the citric acid solution is (4-6): 2.
6. the preparation method according to claim 1 or 5, wherein the reflux temperature is 40-80 ℃ and the time is 2-18 h;
the volume ratio of the mixed solution obtained after refluxing to the ethylene glycol is 42: (0.5-2).
7. The preparation method according to claim 1, wherein the pre-sintering is performed at a temperature of 300 to 400 ℃ for 2 to 6 hours.
8. The method of claim 1 or 7, wherein the firing is performed in an inert atmosphere or under vacuum;
the roasting temperature is 700-1100 ℃, and the roasting time is 2-6 h.
9. Wool-like bulk SiO prepared by the preparation method of any one of claims 1 to 8x[ solution ] A three-dimensionally crosslinked hairline structure comprising a carbon material and SiO wound in the hairline structurex；
The value range of x is 1-2.
10. The wool-ball SiO of claim 9xThe application of the/C as a negative electrode material in a battery.
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