CN115775885B - Silicon-oxygen anode material and preparation method and application thereof - Google Patents
Silicon-oxygen anode material and preparation method and application thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of battery materials, and discloses a silicon-oxygen anode material, a preparation method and application thereof. The silicon-oxygen negative electrode material comprises silicon oxide, an aluminum compound, a carbon nano tube and a carbon layer; the carbon layer is coated with silicon oxide, aluminum compound and carbon nano tube; the length-diameter ratio of the carbon nano tube is not less than 2000; the silica contains crystalline silica. The silicon-oxygen anode material has low volume expansion, high first coulomb efficiency which is not lower than 80 percent, good cycle performance and capacity retention rate which is not lower than 92 percent after 50 weeks of cycle.
Description
Technical Field
The invention belongs to the technical field of battery materials, and particularly relates to a silicon-oxygen anode material, a preparation method and application thereof.
Background
The lithium ion battery has the advantages of high energy density, long service life, no memory effect and the like, so the lithium ion battery is the most widely used energy storage battery at present. Along with the continuous change of application sites, the energy density requirements of lithium ion batteries are higher and higher, for example, mobile phone batteries and electric automobile batteries require the energy density of the lithium ion batteries to be as high as possible.
Because the theoretical capacity of the silicon negative electrode can reach 3580mAh/g, and is much higher than that of the traditional graphite negative electrode (the theoretical capacity is only 372 mAh/g), the silicon negative electrode is one of the most core materials for improving the performance of the lithium ion battery. However, the volume expansion of the silicon negative electrode in the charge and discharge process is large, so that the structure of the negative electrode plate is unstable, and the lithium ion battery is short in service life and quick in performance attenuation. The volume expansion degree of the silicon-oxygen anode material is relatively low, but after multiple cycles, the cycle performance of the lithium ion battery is also obviously attenuated, and particularly, the initial coulomb efficiency is low, which is not beneficial to the practical application of the lithium ion battery.
The prior art (CN 114122340A) discloses a silicon-oxygen composite anode material, which improves the stability and the first coulombic efficiency of the material by introducing carbon nano tubes and a lithium source. However, the dispersion mode of the carbon nanotubes and the combination mode with the silicon oxygen material cannot exert the function of the carbon nanotubes to the greatest extent, and the introduction of the lithium source brings about the first improvement of coulomb efficiency and the reduction of capacitance and the improvement of volume expansion degree, which are unfavorable for the improvement of cycle performance.
The prior art (CN 113422008A) discloses a synthesis method of a micron silicon oxide@carbon nanotube composite lithium ion battery cathode material, wherein a large number of carbon nanotubes are grown on the surface of the silicon oxide in situ, so that the conductivity is improved. However, a large number of carbon nanotubes on the surface increases the specific surface area of the anode material and reduces the compacted density of the anode material, which is disadvantageous in obtaining good cycle performance of the anode material in a battery.
Therefore, it is desirable to provide a novel anode material that not only has high first coulombic efficiency, but also has good cycle performance.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems in the prior art described above. Therefore, the invention provides a silicon-oxygen anode material, and a preparation method and application thereof. The silicon-oxygen anode material has low volume expansion, high first coulomb efficiency which is not lower than 80 percent, good cycle performance and capacity retention rate which is not lower than 92 percent after 50 weeks of cycle.
The invention is characterized in that: the silicon oxide anode material comprises internal silicon oxide, an aluminum compound, a carbon nano tube and a carbon layer on the surface, wherein crystal silicon and crystal silicon dioxide are contained in silicon oxide particles, the carbon layer is coated with the silicon oxide, the aluminum compound and the carbon nano tube, the silicon oxide is in direct contact with the aluminum compound, the carbon nano tube is connected with the carbon layer and a mixture formed by the silicon oxide and the aluminum compound, and the length-diameter ratio of the carbon nano tube is not less than 2000. The carbon nanotubes are stably connected with the silica particles through the coating of the carbon layer. The crystal silicon dioxide can not react with lithium ions in the charge and discharge process, so that the silicon oxide anode material can obtain high first coulombic efficiency in a lithium ion battery. Carbon nano tubes with the length-diameter ratio of more than 2000 form a carbon network in the silicon-oxygen negative electrode material, different particles (silicon oxide) are connected, electrons can be smoothly conducted to the particles when the particles expand or contract, and the structural stability of the silicon-oxygen negative electrode material in the charge-discharge cycle process can be enhanced, so that the cycle performance of the silicon-oxygen negative electrode material is improved.
A first aspect of the present invention provides a silicon oxygen anode material.
Specifically, a silicon oxygen negative electrode material comprises silicon oxide, an aluminum compound, carbon nano tubes and a carbon layer;
the carbon layer coats the silicon oxide, the aluminum compound and the carbon nano tube;
the length-diameter ratio of the carbon nano tube is not less than 2000;
the silicon oxide contains crystal silicon dioxide.
Preferably, the crystal form of the crystal form silicon dioxide is at least one of quartz phase and cristobalite phase.
Preferably, the silicon oxide contains crystalline silicon.
Preferably, the silica has a particle size in the range of 0.5 to 40 μm; further preferably, the silica has a particle size in the range of 0.5 to 30. Mu.m.
Amorphous silica is also included in the silica. The less amorphous silica in the silica of the present invention, the higher the first coulombic efficiency of the silicon oxide negative electrode material.
Preferably, the aspect ratio of the carbon nanotubes is 2000 to 20000; further preferably, the aspect ratio of the carbon nanotubes is 2000 to 5000.
Preferably, the number of the wall layers of the carbon nano tube is 1-5; further preferably, the number of wall layers of the carbon nanotube is 1-3.
Preferably, the thickness of the carbon layer is 3-55nm; further preferably, the thickness of the carbon layer is 5-50nm; more preferably, the thickness of the carbon layer is 10-20nm. The thickness of the carbon layer is on the order of nanometers and may be referred to as a nanocarbon layer.
Preferably, the particle size of the silicon-oxygen anode material is in the range of 1-55 mu m; further preferably, the particle size of the silicon oxide negative electrode material is in the range of 1 to 50 μm.
Preferably, the silicon oxygen cathode material is primary particles and/or secondary particles.
Preferably, the weight of the carbon layer accounts for 2-10% of the total weight of the silicon-oxygen anode material; further preferably, the weight of the carbon layer accounts for 3-5% of the total weight of the silicon-oxygen anode material.
Preferably, the weight of the carbon nano tube accounts for 0.02-0.8% of the total weight of the silicon oxygen anode material; further preferably, the weight of the carbon nanotubes is 0.02-0.5% of the total weight of the silicon oxygen anode material.
Preferably, the weight of the aluminum compound accounts for 0.5-15% of the total weight of the silicon-oxygen anode material; further preferably, the weight of the carbon nanotubes is 1-10% of the total weight of the silicon oxygen anode material.
The second aspect of the invention provides a preparation method of the silicon-oxygen anode material.
Specifically, the preparation method of the silicon-oxygen anode material comprises the following steps:
dispersing the carbon nanotubes to obtain a carbon nanotube dispersion;
mixing the silicon oxide, the aluminum salt and the carbon nano tube dispersion liquid, and drying to obtain a solid mixture;
and heating the solid mixture, adding a carbon source, and preserving heat to obtain the silicon-oxygen anode material.
Preferably, the process of dispersing the carbon nanotubes is as follows: and mixing and dispersing the dispersing agent, the solvent and the carbon nano tube to prepare the carbon nano tube dispersion liquid.
Further preferably, the process of dispersing the carbon nanotubes is as follows: adding a dispersing agent, a solvent and carbon nano tubes into a pre-dispersing device, pre-dispersing for 1-5 hours, and then treating for 1-5 hours in the dispersing device to prepare the carbon nano tube dispersion liquid.
Preferably, the dispersing agent is at least one selected from carboxymethyl cellulose (CMC) and polyvinylpyrrolidone (PVP).
Preferably, the pre-dispersing device comprises a high-speed dispersing machine and a low-speed dispersing machine.
Preferably, the dispersing device comprises a homogenizer and a sand mill.
Preferably, the solvent comprises at least one of water and N-methylpyrrolidone.
Preferably, the mass ratio of the dispersant to the solvent to the carbon nanotubes is 1: (100-500): (0.5-1.5); further preferably, the mass ratio of the dispersant to the solvent to the carbon nanotubes is 1: (200-300): (0.8-1.3).
Preferably, the aluminum salt is at least one selected from aluminum trichloride, aluminum phosphate, aluminum monohydrogen phosphate, aluminum dihydrogen phosphate and aluminum nitrate.
Preferably, a solvent is further added during the mixing of the silica, aluminum salt and the carbon nanotube dispersion.
Preferably, the mass ratio of the silica, the aluminum salt and the carbon nanotube dispersion liquid is 1000: (30-100): (100-400); further preferably, the mass ratio of the silica, the aluminum salt and the carbon nanotube dispersion is 1000: (50-80): (200-300).
Preferably, the drying temperature is 80-120 ℃, and the drying time is 1-10 hours.
Preferably, before the drying, the method further comprises solvent removal treatment. The solvent removal treatment mode comprises filtration or spraying.
Preferably, the heating is performed under a protective gas.
Preferably, the shielding gas includes nitrogen or argon.
Preferably, the temperature of the heating is 650-1000 ℃; further preferably, the temperature of the temperature increase is 700-1000 ℃.
Preferably, the carbon source is a gaseous carbon source.
Further preferably, the carbon source is selected from at least one of methane, ethylene, propylene or acetylene.
Preferably, the time of the heat preservation is 0.5-4 hours; further preferably, the time of the incubation is 1 to 4 hours.
Preferably, after the heat preservation is finished, cooling the material to room temperature under the protection of gas to obtain the silicon-oxygen anode material.
A third aspect of the invention provides the use of a silicon oxygen anode material.
Specifically, the silicon-oxygen anode material is applied to the preparation of batteries.
A battery comprising the silicon oxygen anode material.
Preferably, the battery is a lithium ion battery.
Compared with the prior art, the invention has the following beneficial effects:
(1) The silicon oxide anode material comprises internal silicon oxide, an aluminum compound, a carbon nano tube and a carbon layer on the surface, wherein crystal silicon and crystal silicon dioxide are contained in silicon oxide particles, the carbon layer is coated with the silicon oxide, the aluminum compound and the carbon nano tube, the silicon oxide is in direct contact with the aluminum compound, the carbon nano tube is connected with the carbon layer and a mixture formed by the silicon oxide and the aluminum compound, and the length-diameter ratio of the carbon nano tube is not less than 2000. The carbon nanotubes are stably connected with the silica particles through the coating of the carbon layer. The crystal silicon dioxide can not react with lithium ions in the charge and discharge process, so that the silicon oxide anode material can obtain high first coulombic efficiency in a lithium ion battery. Carbon nano tubes with the length-diameter ratio of more than 2000 form a carbon network in the silicon-oxygen negative electrode material, different particles (silicon oxide) are connected, electrons can be smoothly conducted to the particles when the particles expand or contract, and the structural stability of the silicon-oxygen negative electrode material in the charge-discharge cycle process can be enhanced, so that the cycle performance of the silicon-oxygen negative electrode material is improved.
The silicon-oxygen anode material has low volume expansion, high first coulomb efficiency which is not lower than 80 percent, good cycle performance and capacity retention rate which is not lower than 92 percent after 50 weeks of cycle.
(2) The preparation method of the silicon-oxygen anode material has simple process, is beneficial to industrial mass production and has low cost.
Drawings
FIG. 1 is an X-ray diffraction chart of a silicon oxide negative electrode material prepared in example 1;
fig. 2 is an SEM (scanning electron microscope) image of the silicon oxygen anode material prepared in example 1.
Detailed Description
In order to make the technical solutions of the present invention more apparent to those skilled in the art, the following examples will be presented. It should be noted that the following examples do not limit the scope of the invention.
The starting materials, reagents or apparatus used in the following examples are all available from conventional commercial sources or may be obtained by methods known in the art unless otherwise specified.
Example 1: preparation of silicon-oxygen negative electrode material
A silicon oxygen cathode material, which comprises silicon oxide, aluminum compound, carbon nano tube and carbon layer;
the carbon layer is coated with silicon oxide, aluminum compound and carbon nano tube;
the length-diameter ratio of the carbon nano tube is 2200;
the silicon oxide contains crystalline silicon, crystalline silicon dioxide and amorphous silicon dioxide.
A preparation method of a silicon-oxygen anode material comprises the following steps:
(1) Adding 1g of carboxymethyl cellulose (CMC) and 1g of carbon nano tube into 250g of water, pre-dispersing for 2 hours under the action of a high-speed dispersing machine (the high-speed stirring speed of the high-speed dispersing machine is 800 rpm, the stirring speed of the high-speed dispersing machine is 60 rpm, the stirring speed of the low-speed stirring machine is 1 hour) to obtain a mixed solution, and then adding the mixed solution into a homogenizer (the working pressure of the homogenizer is 100 MPa), and carrying out dispersion treatment for 3 hours to obtain a carbon nano tube dispersion liquid;
(2) Adding 1kg of silicon oxide, 30g of aluminum dihydrogen phosphate and 5kg of water into a carbon nano tube dispersion liquid, mechanically stirring for 2 hours, filtering to remove water, drying in an oven at 80 ℃ for 8 hours, and sieving with a 200-mesh screen to obtain a solid mixture;
(3) And (3) placing the solid mixture in a rotary furnace, charging nitrogen with the flow rate of 1L/min, heating to 930 ℃, charging 2L/min of methane, keeping the temperature for 120 minutes, stopping charging methane, cooling to the room temperature of 20 ℃ under the protection of nitrogen, discharging and screening with a 200-mesh screen to obtain the silicon-oxygen anode material.
Example 2: preparation of silicon-oxygen negative electrode material
A silicon oxygen cathode material, which comprises silicon oxide, aluminum compound, carbon nano tube and carbon layer;
the carbon layer is coated with silicon oxide, aluminum compound and carbon nano tube;
the length-diameter ratio of the carbon nano tube is 2500;
the silicon oxide contains crystalline silicon, crystalline silicon dioxide and amorphous silicon dioxide.
A preparation method of a silicon-oxygen anode material comprises the following steps:
(1) Adding 5g of polyvinylpyrrolidone (PVP) and 4g of carbon nano tubes into 1.2kg of water, pre-dispersing for 1 hour under the action of a high-speed dispersing machine (the high-speed stirring speed of the high-speed dispersing machine is 900 rpm, the stirring speed of the high-speed dispersing machine is 70 rpm, the stirring speed of the low-speed dispersing machine is 0.5 hour, and the stirring speed of the low-speed dispersing machine is 0.5 hour) to obtain a mixed solution, and then adding the mixed solution into a homogenizer (the working pressure of the homogenizer is 90 MPa), and carrying out dispersion treatment for 4 hours to obtain a carbon nano tube dispersion;
(2) Adding 5kg of silicon oxide, 250g of aluminum chloride and 20kg of water into a carbon nano tube dispersion liquid, adding into a homogenizer for dispersion for 3 hours, centrifuging, drying the obtained solid substance in a 100 ℃ oven for 6 hours, and screening by a 200-mesh screen to obtain a solid mixture;
(3) And (3) placing the solid mixture in a rotary furnace, charging nitrogen with the flow rate of 3L/min, heating to 850 ℃, charging 2L/min of acetylene, keeping the temperature for 100 minutes, stopping charging acetylene, cooling to the room temperature of 20 ℃ under the protection of nitrogen, discharging and screening with a 200-mesh screen to obtain the silicon-oxygen anode material.
Example 3: preparation of silicon-oxygen negative electrode material
A silicon oxygen cathode material, which comprises silicon oxide, aluminum compound, carbon nano tube and carbon layer;
the carbon layer is coated with silicon oxide, aluminum compound and carbon nano tube;
the length-diameter ratio of the carbon nano tube is 2300;
the silicon oxide contains crystalline silicon, crystalline silicon dioxide and amorphous silicon dioxide.
A preparation method of a silicon-oxygen anode material comprises the following steps:
(1) Adding 20g of polyvinylpyrrolidone (PVP) and 16g of carbon nano tubes into 8kg of water, pre-dispersing for 1 hour under the action of a high-low speed dispersing machine (the high-speed stirring speed of the high-low speed dispersing machine is 700 rpm, the stirring speed of the high-low speed dispersing machine is 40 rpm, the stirring speed of the low-speed dispersing machine is 0.5 hour, and the stirring speed of the low-speed dispersing machine is 0.5 hour) to obtain a mixed solution, adding the mixed solution into a sand mill, and carrying out dispersing treatment for 5 hours to obtain a carbon nano tube dispersion;
(2) Adding 20kg of silicon oxide, 1kg of aluminum dihydrogen phosphate and 50kg of water into a carbon nano tube dispersion liquid, mechanically stirring for 2 hours, then press-filtering, drying the obtained solid substance in a 120 ℃ oven for 4 hours, and screening by using a 200-mesh screen to obtain a solid mixture;
(3) And (3) placing the solid mixture in a rotary furnace, charging nitrogen with the flow rate of 2L/min, heating to 900 ℃, charging 10L/min of propylene, keeping the temperature for 180 minutes, stopping charging propylene, cooling to the room temperature of 20 ℃ under the protection of nitrogen, discharging and screening with a 200-mesh screen to obtain the silicon-oxygen anode material.
Example 4: preparation of silicon-oxygen negative electrode material
A silicon oxygen cathode material, which comprises silicon oxide, aluminum compound, carbon nano tube and carbon layer;
the carbon layer is coated with silicon oxide, aluminum compound and carbon nano tube;
the aspect ratio of the carbon nano tube is 2600;
the silicon oxide contains crystalline silicon, crystalline silicon dioxide and amorphous silicon dioxide.
A preparation method of a silicon-oxygen anode material comprises the following steps:
(1) Adding 10g of polyvinylpyrrolidone (PVP) and 10g of carbon nano tubes into 3.5kg of N-methyl pyrrolidone, pre-dispersing for 1 hour under the action of a high-low speed dispersing machine (the high-speed stirring speed of the high-low speed dispersing machine is 1000 rpm, the stirring speed of the high-low speed dispersing machine is 50 rpm, the stirring speed of the low-speed dispersing machine is 0.5 hour) to obtain a mixed solution, and then adding the mixed solution into a homogenizer (the working pressure of the homogenizer is 100 MPa), and carrying out dispersion treatment for 4 hours to obtain a carbon nano tube dispersion;
(2) Adding 20kg of silicon oxide, 0.8kg of aluminum phosphate and 60kg of N-methyl pyrrolidone into a carbon nano tube dispersion liquid, adding into a homogenizer for dispersion for 2 hours, then press-filtering, drying the obtained solid substance in a 120 ℃ oven for 4 hours, and screening by using a 200-mesh screen to obtain a solid mixture;
(3) And (3) placing the solid mixture in a rotary furnace, charging nitrogen with the flow rate of 2L/min, heating to 950 ℃, charging 20L/min of methane, keeping the temperature for 180 minutes, stopping charging methane, cooling to the room temperature of 20 ℃ under the protection of nitrogen, discharging and screening with a 200-mesh screen to obtain the silicon-oxygen anode material.
Example 5: preparation of silicon-oxygen negative electrode material
A silicon oxygen cathode material, which comprises silicon oxide, aluminum compound, carbon nano tube and carbon layer;
the carbon layer is coated with silicon oxide, aluminum compound and carbon nano tube;
the length-diameter ratio of the carbon nano tube is 2000;
the silicon oxide contains crystalline silicon, crystalline silicon dioxide and amorphous silicon dioxide.
A preparation method of a silicon-oxygen anode material comprises the following steps:
(1) Adding 10g of carboxymethyl cellulose (CMC) and 12g of carbon nano tubes into 5kg of water, pre-dispersing for 1 hour under the action of a high-low speed dispersing machine (the high-speed stirring speed of the high-low speed dispersing machine is 800 rpm, the stirring speed of the high-low speed dispersing machine is 40 rpm, the stirring speed of the low-speed dispersing machine is 0.5 hour, and the stirring speed of the low-speed dispersing machine is 0.5 hour) to obtain a mixed solution, and then adding the mixed solution into a homogenizer (the working pressure of the homogenizer is 80 MPa), and carrying out dispersion treatment for 5 hours to obtain a carbon nano tube dispersion;
(2) Adding 12kg of silicon oxide, 1kg of aluminum nitrate and 40kg of water into a carbon nano tube dispersion liquid, adding into a homogenizer for dispersion for 1 hour, centrifuging, drying the obtained solid substance in an oven at 80 ℃ for 10 hours, and screening with a 200-mesh screen to obtain a solid mixture;
(3) And (3) placing the solid mixture in a rotary furnace, charging nitrogen with the flow rate of 2L/min, heating to 930 ℃, charging 10L/min of methane, keeping the temperature for 180 minutes, stopping charging methane, cooling to the room temperature of 20 ℃ under the protection of nitrogen, discharging and screening with a 200-mesh screen to obtain the silicon-oxygen anode material.
Comparative example 1 (without carbon nanotubes)
A preparation method of a silicon-oxygen anode material comprises the following steps:
(1) Mixing 1kg of silicon oxide, 30g of aluminum dihydrogen phosphate and 5kg of water, mechanically stirring for 2 hours, then carrying out suction filtration, drying the obtained solid matter in an oven at 80 ℃ for 8 hours, and screening by using a 200-mesh screen to obtain a solid mixture;
(2) And (3) placing the solid mixture in a rotary furnace, charging nitrogen with the flow rate of 1L/min, heating to 930 ℃, charging 2L/min of methane, keeping the temperature for 120 minutes, stopping charging methane, cooling to the room temperature of 20 ℃ under the protection of nitrogen, discharging and screening with a 200-mesh screen to obtain the silicon-oxygen anode material.
Comparative example 2 (without aluminium salt)
A preparation method of a silicon-oxygen anode material comprises the following steps:
(1) Adding 1g of carboxymethyl cellulose (CMC) and 1g of carbon nano tube (with the length-diameter ratio of 2200) into 250g of pure water, pre-dispersing for 2 hours under the action of a high-speed dispersing machine, and then dispersing for 3 hours in a homogenizer to obtain a carbon nano tube dispersion liquid;
(2) Adding 1kg of silicon oxide and 5kg of water into the carbon nano tube dispersion liquid, mechanically stirring for 2 hours, then carrying out suction filtration, drying the obtained solid substance in an oven at 80 ℃ for 8 hours, and screening by using a 200-mesh screen to obtain a solid mixture;
(3) And (3) putting the solid mixture into a rotary furnace, charging nitrogen with the flow rate of 1L/min, heating to 930 ℃, charging 2L/min of methane, keeping the temperature for 120 minutes, stopping charging methane, cooling to room temperature under the protection of nitrogen, discharging and screening with a 200-mesh screen to obtain the silicon-oxygen anode material.
Comparative example 3
A preparation method of a silicon-oxygen anode material comprises the following steps:
(1) Adding 1g of carboxymethyl cellulose (CMC) and 5g of multi-wall carbon nano tube (length-diameter ratio is 30) into 250g of water, pre-dispersing for 2 hours under the action of a high-speed dispersing machine, and then dispersing for 3 hours in a homogenizer to obtain multi-wall carbon nano tube dispersion liquid;
(2) Adding 1kg of silicon oxide, 30g of aluminum dihydrogen phosphate and 5kg of water into the multiwall carbon nanotube dispersion, mechanically stirring for 2 hours, then carrying out suction filtration, drying the obtained solid matter in an oven at 80 ℃ for 8 hours, and screening by using a 200-mesh screen to obtain a solid mixture;
(3) And (3) putting the solid mixture into a rotary furnace, charging nitrogen with the flow rate of 1L/min, heating to 930 ℃, charging 2L/min of methane, keeping the temperature for 120 minutes, stopping charging methane, cooling to room temperature under the protection of nitrogen, discharging and screening with a 200-mesh screen to obtain the silicon-oxygen anode material.
Comparative example 4
A preparation method of a silicon-oxygen anode material comprises the following steps:
(1) 1kg of silicon oxide, 30g of aluminum dihydrogen phosphate and 5kg of water are mechanically stirred for 2 hours, and then suction filtration is carried out, the obtained solid matter is placed in an oven at 80 ℃ for drying for 8 hours, and screening is carried out by a 200-mesh screen to obtain a mixture A;
(2) Putting the mixture A into a rotary furnace, charging nitrogen with the flow rate of 1L/min, heating to 930 ℃, charging 2L/min of methane, keeping the temperature for 120 minutes, stopping charging methane, cooling to the room temperature of 20 ℃ under the protection of nitrogen, discharging and screening by a 200-mesh screen to obtain a mixture B;
(3) Adding 1g of carboxymethyl cellulose (CMC) and 1g of carbon nano tube (with the length-diameter ratio of 2200) into 250g of water, pre-dispersing for 2 hours under the action of a high-speed dispersing machine, and then dispersing for 3 hours in a homogenizer to obtain a carbon nano tube dispersion liquid;
(4) Adding the mixture B and 5kg of water into the carbon nano tube dispersion liquid, mechanically stirring for 2 hours, then carrying out suction filtration, drying the obtained solid substance in an oven at 80 ℃ for 8 hours, and screening by using a 200-mesh screen to obtain the silicon-oxygen anode material.
Product effect test
1. Example 1 silicon oxygen negative electrode Material structural characterization
FIG. 1 is an X-ray diffraction chart of a silicon oxide negative electrode material prepared in example 1; as can be seen from FIG. 1 (the ordinate "Intensity" of FIG. 1 shows the Intensity), the silicon oxide negative electrode material contains a cristobalite phase, crystalline silicon and a small amount of quartz phase, and a broad peak between 16 and 26 degrees represents amorphous silica.
Fig. 2 is an SEM (scanning electron microscope) image of the silicon oxygen anode material prepared in example 1. As can be seen from fig. 2, in the silicon-oxygen negative electrode material, the carbon nanotubes with a large length-diameter ratio form a conductive network, and the particles are connected in series, which is beneficial to maintaining good electrical contact performance of the active particles in the charge-discharge process, so that the cycle stability of the silicon-oxygen negative electrode material is improved.
2. Performance test of silicon-oxygen negative electrode material
The silicon-oxygen cathode material prepared in example 1, PAA (polyacrylic acid) and conductive agent Super-P are mixed according to the weight ratio of 85:5:10, deionized water is added as a dispersing agent to prepare slurry, the slurry is coated on copper foil, and the slurry is subjected to vacuum drying, rolling and sheet punching to prepare a pole piece, wherein the counter electrode is a metal lithium sheet, and the electrolyte adopts 1.0mol/L LiPF 6 The solution (solvent composition in the solution is ethyl carbonate EC: dimethyl carbonate DMC: fluoroethylene carbonate FEC=4:5.5:0.5 (volume ratio)), the membrane adopts a polypropylene microporous membrane to assemble a CR2016 button cell, the charge and discharge test uses 150mA/g current density to conduct constant current discharge to 0.005V, then 30mA/g current density to conduct constant current discharge to 0.005V, and then 150mA/g constant current charge to 1.5V, and corresponding electrical properties are obtained, and the results are shown in Table 1.
The silicon oxygen anode materials prepared in examples 2 to 5 and comparative examples 1 to 4 were also tested for the corresponding electrical properties by the above-mentioned method, and the results are shown in Table 1.
TABLE 1
As can be seen from Table 1, after the silicon-oxygen anode materials prepared in examples 1-5 of the present invention are assembled into a battery, the corresponding first coulomb efficiency and the cycle 50 week capacity retention rate are high, which are significantly better than the corresponding performances of comparative examples 1-4.
As can be further seen from table 1, the silicon oxygen anode material of comparative example 1 was prepared without using carbon nanotubes, resulting in a decrease in cycle performance. The silicon oxygen anode material of comparative example 2 was prepared without using aluminum salt, resulting in low initial coulombic efficiency. The multiwall carbon nanotubes used in the preparation of the silicon oxygen negative electrode material of comparative example 3 have a small long diameter, resulting in unstable structure and reduced cycle performance. The silicon-oxygen anode material prepared by the preparation method in comparative example 4 has the advantages that the carbon nanotubes are not contacted with the silicon oxide and the aluminum salt, and the particles and the carbon layer cannot be effectively connected, so that the structural stability is poor, and the cycle performance is reduced.
Claims (9)
1. The silicon-oxygen anode material is characterized by comprising the following components: silicon oxide, aluminum compounds, carbon nanotubes and carbon layers;
the carbon layer coats the silicon oxide, the aluminum compound and the carbon nano tube;
the length-diameter ratio of the carbon nano tube is not less than 2000;
the silicon oxide contains crystal silicon dioxide;
the crystal form of the crystal form silicon dioxide is at least one of quartz phase and cristobalite phase;
the weight of the aluminum compound accounts for 0.5-15% of the total weight of the silicon-oxygen anode material;
the silicon oxide is in direct contact with the aluminum compound, and the carbon nano tube is connected with the mixture formed by the silicon oxide and the aluminum compound and the carbon layer;
the preparation method of the silicon-oxygen anode material comprises the following steps:
dispersing the carbon nanotubes to obtain a carbon nanotube dispersion;
mixing the silicon oxide, the aluminum salt and the carbon nano tube dispersion liquid, and drying to obtain a solid mixture;
and heating the solid mixture, adding a carbon source, and preserving heat to obtain the silicon-oxygen anode material.
2. The silicon-oxygen anode material according to claim 1, wherein the number of wall layers of the carbon nanotube is 1 to 5.
3. The silicon-oxygen anode material according to claim 1, wherein the thickness of the carbon layer is 3-55nm.
4. The silicon-oxygen anode material according to claim 1, wherein the particle size of the silicon-oxygen anode material is in the range of 1 to 55 μm.
5. The silicon-oxygen anode material according to claim 1, wherein the weight of the carbon layer is 2-10% of the total weight of the silicon-oxygen anode material; the weight of the carbon nano tube accounts for 0.02-0.8% of the total weight of the silicon-oxygen anode material.
6. The method for producing a silicon-oxygen anode material according to any one of claims 1 to 5, comprising the steps of:
dispersing the carbon nanotubes to obtain a carbon nanotube dispersion;
mixing the silicon oxide, the aluminum salt and the carbon nano tube dispersion liquid, and drying to obtain a solid mixture;
and heating the solid mixture, adding a carbon source, and preserving heat to obtain the silicon-oxygen anode material.
7. The method according to claim 6, wherein the aluminum salt is at least one selected from aluminum trichloride, aluminum phosphate, aluminum monohydrogen phosphate, aluminum dihydrogen phosphate and aluminum nitrate.
8. Use of a silicon oxygen anode material according to any one of claims 1-5 for the preparation of a battery.
9. A battery comprising the silicon-oxygen anode material of any one of claims 1 to 5.
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| CN110176601A (en) * | 2019-05-20 | 2019-08-27 | 合肥国轩高科动力能源有限公司 | Carbon-coated silicon monoxide negative electrode material and preparation method and application thereof |
| CN111463423A (en) * | 2020-04-07 | 2020-07-28 | 山东斯艾诺德新材料科技有限公司 | Preparation method of negative electrode material of silicon oxide lithium ion battery and preparation method of negative electrode piece of battery |
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| CN113725409A (en) * | 2021-07-29 | 2021-11-30 | 合肥国轩高科动力能源有限公司 | Silicon-based negative electrode material and preparation method thereof |
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| CN114122397A (en) * | 2021-10-12 | 2022-03-01 | 湖南金硅科技有限公司 | Carbon nanotube-connected dual-carbon-layer-coated mesoporous silica composite material and preparation method and application thereof |
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| CN113725409A (en) * | 2021-07-29 | 2021-11-30 | 合肥国轩高科动力能源有限公司 | Silicon-based negative electrode material and preparation method thereof |
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