CN111082020B - Dispersion distribution metal silicide/nano silicon composite material and preparation method thereof - Google Patents

Dispersion distribution metal silicide/nano silicon composite material and preparation method thereof Download PDF

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CN111082020B
CN111082020B CN201911379430.8A CN201911379430A CN111082020B CN 111082020 B CN111082020 B CN 111082020B CN 201911379430 A CN201911379430 A CN 201911379430A CN 111082020 B CN111082020 B CN 111082020B
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silicon
composite material
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metal silicide
metal
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唐晶晶
杨娟
周向阳
罗楚城
周昊宸
王鹏
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Hunan Chenyu Fuji New Energy Technology Co ltd
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Central South University
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Abstract

The invention discloses a dispersion distribution metal silicide/nano-silicon composite material and a preparation method thereof, wherein the composite material consists of metal silicide and nano-silicon particles, wherein part of the metal silicide is dispersed and distributed in the nano-silicon, and the other part of the metal silicide covers the surfaces of the nano-silicon particles; the composite material comprises 0.89-16.45% of metal silicide by mass and the balance of silicon. The dispersion-distributed metal silicide/nano-silicon composite material has the advantages that the specific metal silicide with the dispersion strengthening effect is inserted into the nano-silicon particles and is dispersed and distributed, and the metal silicide coating layer is formed on the surface of the specific metal silicide, so that the cycle performance and the stability of the composite material when the composite material is applied to a lithium ion battery cathode material are far superior to those of the conventional nano-silicon cathode material.

Description

Dispersion distribution metal silicide/nano silicon composite material and preparation method thereof
Technical Field
The invention belongs to the technical field of lithium ion battery electrode materials, and particularly relates to a dispersion distribution metal silicide/nano silicon composite material and a preparation method thereof.
Background
At present, the energy density and power density of the lithium ion battery are difficult to break through due to the low theoretical capacity of the graphite material. The development of the novel lithium ion battery cathode material with high specific volume, stable structure and excellent cycling stability has practical significance for the improvement of the performance of the lithium ion battery and the expansion of the application. Among the alternative materials of graphite cathodes, the silicon-based material has high theoretical lithium storage capacity, appropriate potential platform, relative safety and wide raw material source, and is the most promising novel cathode material. However, many problems are still not solved at present. These problems are mainly the low intrinsic conductivity of silicon and the volume effect, structural instability, etc. during cycling, which severely hamper the commercial application of silicon materials. In order to solve the problems of silicon materials, the existing modification method mainly comprises the preparation of nano and composite materials.
The performance of the nano-silicon particles is improved mainly based on the nano-size effect, so that the ion transmission path can be shortened, and the volume expansion of the silicon particles in the charging and discharging processes can be relieved. The existing preparation method mainly comprises chemical or electrochemical etching, rapid cooling, laser ablation, silicon tetrachloride reduction, silane pyrolysis and the like, but generally has the defects of high cost, complex equipment, high toxicity and low yield, and is not beneficial to large-scale production and preparation of the nano silicon material. In addition, the problem of low intrinsic conductivity of the nano silicon material is still not solved.
The nano silicon material is compounded with the high-conductivity substrate material, and the method is an effective way for improving the conductivity of the composite material. Patent CN102916167A discloses a mesoporous silicon composite composed of a mesoporous silicon phase, a metal silicide phase and a carbon phase, the first discharge specific capacity is 1595.4mAh/g, the first charge specific capacity is 931.9mAh/g, the first coulombic efficiency is 58.4%, but the metal phase is introduced by a solution impregnation method, and does not enter the interior of the original silicon particles, the interface bonding strength with other silicon particles is low, the size of the metal phase particles is large, and the metal phase particles are difficult to be uniformly distributed in the interior of the carbon-coated silicon particle structure, the reinforcing effect is limited, and the reversible capacity is low.
Disclosure of Invention
The invention aims to provide a dispersion distribution metal silicide/nano silicon composite material with nano size and high reversible capacity and a preparation method thereof.
The dispersion distribution metal silicide/nano silicon composite material consists of metal silicide and nano silicon particles, wherein part of the metal silicide is dispersed and distributed in the nano silicon, and the other part of the metal silicide covers the surfaces of the nano silicon particles; the composite material comprises 0.89-16.45% of metal silicide by mass and the balance of silicon.
The particle size of the silicon nano-particles is 5-100 nm, the particle size of the metal silicide dispersed in the silicon nano-particles is 0.1-10 nm, and the thickness of the metal silicide layer coated on the surfaces of the silicon nano-particles is 1-10 nm.
The specific surface area of the dispersion distribution metal silicide/nano silicon composite material is 10-500 m2 g-1。
The preparation method of the dispersion distribution metal silicide/nano silicon composite material comprises the following steps:
1) preparing a composite precursor: dispersing metal oxolate, a silicon source and a solid ammonia source in a solvent, uniformly stirring, carrying out hydrothermal reaction under set conditions, and filtering, washing and drying after the reaction is finished to obtain a composite precursor;
2) preparing a composite material: uniformly mixing the composite precursor prepared in the step 1), the reducing metal and the metal chloride, carrying out two-stage heat treatment in a protective atmosphere, and after the treatment, carrying out acid washing, water washing, filtering and drying on the product to obtain the composite material.
In the step 1), the metal in the oxometalate is one of tungsten, molybdenum, niobium, tantalum and vanadium, preferably one of tungsten and molybdenum, and more preferably, the oxometalate is one of ammonium metatungstate and ammonium molybdate; the liquid silicon source is one or more of sodium silicate, potassium silicate, ethyl orthosilicate and methyl orthosilicate, and preferably ethyl orthosilicate; the solid ammonia source is one or more of urea, thiourea, biuret, methylol urea, isobutyl diurea, urea formaldehyde and urea acetaldehyde, and preferably urea; the solvent is a mixed solvent of water and alcohol, and the volume ratio of the water to the alcohol is 1: 0.02-20; the mass ratio of the metal oxosalt to the liquid silicon source to the solid ammonia source is 1 (2.2-18.3) to (2-12), and the mass volume ratio of the metal oxosalt to the mixed solvent is 0.25-1.40 to (85-91) g/mL; the hydrothermal reaction temperature is 180-220 ℃, and the reaction time is 6-48 h.
In the step 2), the reducing metal is one or more of lithium, sodium, potassium, calcium, zinc, magnesium, aluminum and the like; the metal chloride salt is one or more of potassium chloride, sodium chloride, magnesium chloride, zinc chloride and aluminum chloride; the mass ratio of the composite precursor to the reducing metal salt is 1: 0.5-2: 1-15; the protective atmosphere is one or more of hydrogen, argon, helium and the like; the two-stage heat treatment comprises a first-stage low-temperature pretreatment and a second-stage high-temperature reduction treatment; the low-temperature pretreatment temperature is 350-450 ℃, and the treatment time is 0.5-5 h; the high-temperature reduction treatment temperature is 600-800 ℃, and the treatment time is 1-12 h; the acid washing adopts 05-2.5 mol/L hydrochloric acid.
The preparation principle of the invention is as follows: the preparation method of the invention adopts a specific solid ammonia source as a reaction control agent, provides an alkaline environment required by the reaction, and simultaneously slowly and uniformly releases crystal-forming ions in the solution, ensures that decomposition and precipitation are in a balanced state, thereby uniformly separating out metal oxide and silicic acid monomer, and can obtain a silicon dioxide composite precursor which is different from hydrolyzed silicon oxide and has metal oxide dispersed and distributed inside and a metal oxide coating layer on the surface by adjusting the reaction conditions. And then reducing the precursor into the metal silicide/silicon composite material by adopting a metallothermic reduction reaction with the aid of metal chloride. The generation of the metal silicide is a strong endothermic reaction, the heat released by the silicon reduction reaction can be effectively utilized, and the reaction is controlled to be carried out mildly, so that a product which contains the metal silicide in dispersion distribution and has a metal silicide coating layer on the surface is prepared.
The invention has the beneficial effects that: the dispersion-distributed metal silicide/nano-silicon composite material has the advantages that the specific metal silicide with the dispersion strengthening effect is inserted into the nano-silicon particles and is dispersed and distributed, and the metal silicide coating layer is formed on the surface of the specific metal silicide, so that the cycle performance and the stability of the composite material when the composite material is applied to a lithium ion battery cathode material are far superior to those of the conventional nano-silicon cathode material. The advantages mainly include the following methods:
(1) the metal silicide dispersed in the nano silicon particles in the composite material has a dispersion strengthening effect, and can relieve the volume change of silicon in the charging and discharging process, so that the cycling stability of the silicon as a lithium ion battery material is improved.
(2) The metal silicide coated on the surface of the nano silicon particles in the composite material can relieve the volume change of silicon in the charge and discharge process, and is beneficial to maintaining the structural stability.
(3) The electrical conductivity of the selected metal silicide in the composite material is far higher than that of silicon, so that the electrical conductivity of the silicon-based composite material can be greatly improved, and the performance of silicon as a lithium ion battery material is favorably improved.
(4) The metal silicide which is dispersedly distributed in the nano silicon particles and coated on the surfaces of the nano silicon particles is synchronously realized, and the obtained nano silicon has uniform appearance and size.
(5) The composite material has the advantages of simple preparation process, environmental friendliness, low cost, high yield and suitability for industrial production, and the prepared metal silicide/silicon composite material has high reversible capacity, long cycle life and good rate capability.
(6) The invention firstly generates the metal silicide which is dispersed and distributed in situ in the nano silicon particles, and synchronously generates a metal silicide coating layer on the surface of the nano silicon particles. The metal silicide distributed in a dispersion mode not only improves the conductivity of the silicon-based material, but also has a dispersion strengthening effect and is beneficial to maintaining the structural stability of silicon; the metal silicide coating layer on the surface of the silicon particle can also improve the conductivity of the silicon material, limit the volume effect of the silicon material in the lithium extraction process and improve the cycle stability.
Drawings
FIG. 1 XRD pattern of the silicon nanomaterial prepared in comparative example 2;
FIG. 2 Performance graph of the composite prepared in example 2;
FIG. 3a microtopography of the composite prepared in example 2, (a) TEM-1 image of the composite; (b) TEM-2 image of the composite material; (c) a schematic structural diagram of the composite material;
FIG. 4 elemental profile of the composite prepared in example 2;
figure 5 XRD pattern of the composite material prepared in example 2.
Detailed Description
Example 1
1. Dispersing 4.5mL of ethyl orthosilicate in 45mL of ethanol to obtain a mixed solution 1; 1.38g of ammonium metatungstate and 3.83g of urea were dispersed in 41mL of a solvent composed of ethanol and water (the volume ratio of ethanol to water was 16:25) to obtain a mixed solution 2 in which the molar ratio of tungsten to silicon element was 1:3 (the molar ratio was calculated as the molar ratio of silicon to metal element in silica produced by hydrolysis in accordance with the theory of a liquid silicon source, and the same was applied to the subsequent examples); and quickly pouring the mixed solution 2 into the mixed solution 1, stirring at room temperature of 650r/min for 30min, carrying out hydrothermal reaction at 200 ℃ for 12h to obtain colloidal precipitate, filtering, washing the precipitate with water to be neutral, and drying at 60 ℃ to obtain the tungsten silicide/silicon dioxide composite precursor.
2. Taking 1g of tungsten silicide/silicon dioxide composite precursor powder, mixing with 10g of sodium chloride, adding 0.9g of metal magnesium powder, placing in a sealed tube furnace, heating to 400 ℃ at the speed of 5 ℃/min under the argon atmosphere, preserving heat for 0.5h, heating to 700 ℃ at the speed of 5 ℃/min, preserving heat for 10h, cooling, treating the product in 1mol/L hydrochloric acid for 6h, filtering, washing to be neutral, and drying at the temperature of 60 ℃ to obtain the tungsten silicide/nano silicon composite material.
In the tungsten silicide/nano-silicon composite material prepared in this example, WSi2The mass fraction of (A) is 16.45%; the average particle diameter of the composite material is 54nm, the average particle diameter of the silicon particles is 40nm, the thickness of the tungsten silicide coating layer is 7nm, and the specific surface area of the composite material is 186m2 g-1。
The tungsten silicide/nano silicon composite material and the conductive material prepared by the embodimentPreparing electric carbon black and sodium alginate into slurry according to the mass ratio of 6:2:2, coating the slurry on a copper foil, and drying the copper foil at 60 ℃ for 12 hours to prepare the lithium ion battery negative plate. A button cell CR2025 is used as a simulation cell, a metal lithium sheet is used as a counter electrode, and the electrolyte component is 1MLiPF6(ethylene carbonate: diethyl carbonate ═ 1:1, v/v), septum Celgard2400, and assembly was completed in a glove box filled with argon atmosphere. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The first reversible specific capacity of the battery can reach 1600mAh/g, and the reversible specific capacity is 1300mAh/g after 200 cycles of circulation.
Comparative example 1
Mixing 1g of commercial nano silicon dioxide powder with 10g of sodium chloride, adding 0.9g of metal magnesium powder, placing the mixture in a sealed tube furnace, heating to 400 ℃ at the speed of 5 ℃/min under the argon atmosphere, preserving heat for 0.5h, heating to 700 ℃ at the speed of 5 ℃/min, preserving heat for 10h, treating the cooled product in 1mol/L hydrochloric acid for 6h, filtering, washing to be neutral, and drying at the temperature of 80 ℃ to obtain the reaction product, namely nano silicon.
The average particle diameter of the nano silicon particles prepared by the comparative example is 60nm, and the specific surface area of the material is 120m2g-1。
Preparing the nano silicon material prepared by the comparative example, conductive carbon black and sodium alginate into slurry according to the mass ratio of 6:2:2, coating the slurry on copper foil, and drying the copper foil at 60 ℃ for 12 hours to prepare the lithium ion battery negative plate. A button cell CR2025 is used as a simulation cell, a metal lithium sheet is used as a counter electrode, and the electrolyte component is 1MLiPF6(ethylene carbonate: diethyl carbonate ═ 1:1, v/v), septum Celgard2400, and assembly was completed in a glove box filled with argon atmosphere. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The first reversible specific capacity of the battery is 1470mAh/g, and the reversible specific capacity is lower than 100mAh/g after the battery is cycled for 200 circles.
Compared with the performance of the embodiment 1, the first reversible specific capacity of the embodiment 1 is relatively higher, and the key is that the reversible specific capacity of the invention is obviously superior to that of the comparative example 1, which shows that the distribution of tungsten silicide in the embodiment 1 can relieve the volume change of silicon in the charging and discharging process, thereby improving the cycling stability of the silicon as the lithium ion battery material. And the metal silicide coated on the surface of the nano silicon particles can relieve the volume change of silicon in the charge and discharge process, and is favorable for maintaining the structural stability.
Comparative example 2
1. Dispersing 4.5mL of ethyl orthosilicate in 45mL of ethanol to obtain a mixed solution 1; 3.834g of urea is dispersed in 41mL of solvent consisting of ethanol and water (the volume ratio of the ethanol to the water is 16:25) to obtain a mixed solution 2; and quickly pouring the mixed solution 2 into the mixed solution 1, stirring at room temperature of 650r/min for 30min, carrying out hydrothermal reaction at 200 ℃ for 12h to obtain colloidal precipitate, filtering, washing the precipitate with water to be neutral, and drying at 60 ℃ to obtain a silicon dioxide precursor.
2. Taking 1g of silicon dioxide composite precursor powder, mixing with 10g of sodium chloride, adding 0.9g of metal magnesium powder, placing in a sealed tube furnace, heating to 400 ℃ at the speed of 5 ℃/min under the argon atmosphere, preserving heat for 0.5h, heating to 700 ℃ at the speed of 5 ℃/min, preserving heat for 10h, treating the cooled product in 1mol/L hydrochloric acid for 6h, filtering, washing to neutrality by water, and drying at the temperature of 60 ℃ to obtain the nano silicon material.
In the nano silicon material prepared by the comparative example, the average particle size of silicon particles is 55nm, and the specific surface area of the material is 160m2 g-1。
Preparing the prepared nano silicon, conductive carbon black and sodium alginate into slurry according to the mass ratio of 6:2:2, coating the slurry on copper foil, and drying the copper foil at 60 ℃ for 12 hours to prepare the lithium ion battery negative plate. A button cell CR2025 is used as a simulation cell, a metal lithium sheet is used as a counter electrode, and the electrolyte component is 1MLiPF6(ethylene carbonate: diethyl carbonate ═ 1:1, v/v), septum Celgard2400, and assembly was completed in a glove box filled with argon atmosphere. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The first reversible specific capacity of the battery is 1500mAh/g, and the reversible specific capacity after 200 cycles is 600 mAh/g.
Like the comparative example 1, the first reversible specific capacity of the nano silicon particles prepared by the method of the invention is relatively low, and the reversible specific capacity is obviously worse than that of the example 1.
The XRD analysis of the nano-silicon prepared in this comparative example is shown in fig. 1, and it can be seen from fig. 1 that there is no absorption peak of tungsten silicide in this comparative example.
Comparative example 3
1. Dispersing 4.5mL of ethyl orthosilicate in 45mL of ethanol to obtain a mixed solution 1; dispersing 1.38g of ammonium metatungstate and 9mL of ammonia water in 41mL of a solvent consisting of ethanol and water (the volume ratio of the ethanol to the water is 16:25) to obtain a mixed solution 2; and quickly pouring the mixed solution 2 into the mixed solution 1, stirring at room temperature of 650r/min for 30min, carrying out hydrothermal reaction at 200 ℃ for 12h to obtain colloidal precipitate, filtering, washing the precipitate with water to be neutral, and drying at 60 ℃ to obtain precursor powder (the precursor is not tested in the preparation process, but the final product does not contain tungsten silicide).
2. Taking 1g of precursor powder, mixing with 10g of sodium chloride, adding 0.9g of metal magnesium powder, placing in a sealed tube furnace, heating to 400 ℃ at the speed of 5 ℃/min under the argon atmosphere, preserving heat for 0.5h, heating to 700 ℃ at the speed of 5 ℃/min, preserving heat for 10h, cooling, treating the product in 1mol/L hydrochloric acid for 6h, filtering, washing to be neutral, and drying at the temperature of 60 ℃ to obtain the nano silicon material.
And (3) preparing the material prepared in the comparative example, conductive carbon black and sodium alginate into slurry according to the mass ratio of 6:2:2, coating the slurry on copper foil, and drying at 60 ℃ for 12 hours to prepare the lithium ion battery negative plate. A button cell CR2025 is used as a simulation cell, a metal lithium sheet is used as a counter electrode, and the electrolyte component is 1MLiPF6(ethylene carbonate: diethyl carbonate ═ 1:1, v/v), septum Celgard2400, and assembly was completed in a glove box filled with argon atmosphere. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The first reversible specific capacity of the battery is 1580mAh/g, and the reversible specific capacity is 900mAh/g after 200 cycles of circulation.
In the comparative example, ammonia water is used as an ammonia source, ammonium metatungstate does not react in the hydrolysis precipitation process, and tungsten does not enter SiO2In the precursor, only silicon dioxide obtained by final preparation does not have tungsten oxide, and the cycle-to-reversible specific capacity of the composite material obtained by final preparation is slightly improved, which is far inferior to that of example 1.
Example 2
1. Dispersing 4.5mL of ethyl orthosilicate in 45mL of ethanol to obtain a mixed solution 1; dispersing 1.03g of ammonium metatungstate and 3.834g of urea in 41mL of a solvent consisting of ethanol and water (the volume ratio of the ethanol to the water is 16:25) to obtain a mixed solution 2, wherein the molar ratio of the added tungsten to the silicon element is 1: 4; and quickly pouring the mixed solution 2 into the mixed solution 1, stirring at room temperature of 650r/min for 30min, carrying out hydrothermal reaction at 200 ℃ for 12h to obtain colloidal precipitate, filtering, washing the precipitate with water to be neutral, and drying at 60 ℃ to obtain the tungsten silicide/silicon dioxide composite precursor.
2. Taking 1g of tungsten silicide/silicon dioxide composite precursor powder, mixing with 10g of sodium chloride, adding 0.9g of metal magnesium powder, placing in a sealed tube furnace, heating to 400 ℃ at the speed of 5 ℃/min under the argon atmosphere, preserving heat for 0.5h, heating to 700 ℃ at the speed of 5 ℃/min, preserving heat for 10h, treating the cooled product in 1mol/L hydrochloric acid for 6h, filtering, washing to be neutral, and drying at the temperature of 60 ℃ to obtain the nano tungsten silicide/silicon particle composite material.
The composite material prepared by the embodiment, conductive carbon black and sodium alginate are prepared into slurry according to the mass ratio of 6:2:2, the slurry is coated on copper foil, and the lithium ion battery negative plate is prepared after drying for 12 hours at 60 ℃. The assembly was completed in a glove box filled with argon atmosphere, using a button cell CR2025 as a dummy cell, a metal lithium plate as a counter electrode, an electrolyte composition of 1MLiPF6 (ethylene carbonate: diethyl carbonate: 1, v/v), and a separator of Celgard 2400. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The results are shown in FIG. 2: as can be seen from the figure, under the current density of 840mAh/g, the first reversible specific capacity of the battery can reach 2000mAh/g, and the reversible specific capacity after 50 cycles is 1750 mAh/g.
The TEM test of the composite material prepared in this example is shown in fig. 3a and 3b, and we can see that the composite material has a uniform size, an average size of 50nm, an average size of 40nm, and a thickness of a tungsten silicide shell layer coated on the surface of the silicon particle of 5nm, and we can clearly see that the tungsten silicide particles are dispersed and distributed in the silicon particle. From the above topographical map, the microstructure of the composite material of the present invention is shown in fig. 3 c.
WSi in the composite Material in this example2Is 7.51% by mass, and has a specific surface area of 183m2g-1。
As a result of XRD analysis of the composite material prepared in this example, as shown in fig. 4, the composite material has an absorption peak of tungsten silicide in addition to an absorption peak of silicon, as compared with fig. 1.
The composite material prepared in this example was subjected to element distribution analysis, and the result is shown in fig. 5, in which tungsten is uniformly distributed in the silicon matrix, and the XRD spectrum shows that WSi is provided inside the composite material prepared in this example2The nano silicon material in dispersed distribution has black and white picture, and the color of W element in the analysis picture is darker, so that in the condition of color picture, it can be seen that there is a layer of W element distribution at the peripheral edge of the particle.
Example 3
1. Dispersing 4.5mL of ethyl orthosilicate in 45mL of ethanol to obtain a mixed solution 1; dispersing 0.69g of ammonium metatungstate and 3.834g of urea in 41mL of solvent consisting of ethanol and water (the volume ratio of the ethanol to the water is 16:25) to obtain a mixed solution 2, wherein the molar ratio of the added tungsten to the silicon element is 1: 6; and quickly pouring the mixed solution 2 into the mixed solution 1, stirring at room temperature of 650r/min for 30min, carrying out hydrothermal reaction at 190 ℃ for 24h to obtain colloidal precipitate, filtering, washing the precipitate with water to be neutral, and drying at 60 ℃ to obtain the tungsten silicide/silicon dioxide composite precursor.
2. Taking 1g of metal silicide/silicon dioxide composite precursor powder, mixing with 10g of sodium chloride, adding 0.9g of metal magnesium powder, placing in a sealed tube furnace, heating to 400 ℃ at the speed of 5 ℃/min under the argon atmosphere, preserving heat for 0.5h, heating to 700 ℃ at the speed of 5 ℃/min, preserving heat for 10h, treating the cooled product in 1mol/L hydrochloric acid for 6h, filtering, washing to be neutral, and drying at the temperature of 60 ℃ to obtain the tungsten silicide/nano silicon particle composite material.
In the composite material prepared in this example, WSi2The mass fraction of (A) is 4.13%; the average particle diameter of the composite material is 48nm, the average particle diameter of the silicon particles is 40nm, the thickness of the tungsten silicide coating layer is 4nm, and the specific surface area of the composite material is 178m2g-1。
And (3) preparing the prepared composite material, conductive carbon black and sodium alginate into slurry according to the mass ratio of 6:2:2, coating the slurry on a copper foil, and drying at 60 ℃ for 12 hours to prepare the lithium ion battery negative plate. A button cell CR2025 is used as a simulation cell, a metal lithium sheet is used as a counter electrode, and the electrolyte component is 1MLiPF6(ethylene carbonate: diethyl carbonate ═ 1:1, v/v), septum Celgard2400, and assembly was completed in a glove box filled with argon atmosphere. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The first reversible specific capacity of the battery can reach 2000mAh/g, and the reversible specific capacity is 1600mAh/g after 200 cycles of circulation.
Example 4
1. Dispersing 4.5mL of ethyl orthosilicate in 45mL of ethanol to obtain a mixed solution 1; dispersing 0.52g of ammonium metatungstate and 3.834g of urea in 41mL of solvent consisting of ethanol and water (the volume ratio of the ethanol to the water is 16:25) to obtain a mixed solution 2, wherein the molar ratio of the added tungsten to the silicon is 1: 8; and quickly pouring the mixed solution 2 into the mixed solution 1, stirring at room temperature of 650r/min for 30min, carrying out hydrothermal reaction at 200 ℃ for 12h to obtain colloidal precipitate, filtering, washing the precipitate with water to be neutral, and drying at 60 ℃ to obtain the tungsten silicide/silicon dioxide composite precursor.
2. Taking 1g of tungsten silicide/silicon dioxide composite precursor powder, mixing with 10g of sodium chloride, adding 0.9g of metal magnesium powder, placing in a sealed tube furnace, heating to 400 ℃ at the speed of 5 ℃/min under the argon atmosphere, preserving heat for 0.5h, heating to 700 ℃ at the speed of 5 ℃/min, preserving heat for 10h, treating the cooled product in 1mol/L hydrochloric acid for 6h, filtering, washing to be neutral, and drying at the temperature of 60 ℃ to obtain the tungsten silicide/nano silicon composite material.
In the tungsten silicide/nano-silicon composite material prepared in this example, WSi2The mass fraction of (A) is 2.28%; the average particle diameter of the composite material is 47nm, the average particle diameter of the silicon particles is 40nm, the thickness of the tungsten silicide coating layer is 3.5nm, and the specific surface area of the composite material is 174m2 g-1。
The material prepared by the embodiment, conductive carbon black and sodium alginate are prepared into slurry according to the mass ratio of 6:2:2, the slurry is coated on copper foil, and the lithium ion battery negative plate is prepared after drying for 12 hours at 60 ℃. A button cell CR2025 is used as a simulation cell, a metal lithium sheet is used as a counter electrode, and the electrolyte component is 1MLiPF6(ethylene carbonate: diethyl carbonate ═ 1:1, v/v), septum Celgard2400, and assembly was completed in a glove box filled with argon atmosphere. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The first reversible specific capacity of the battery can reach 1500mAh/g, and the reversible specific capacity is 1300mAh/g after 200 cycles of circulation.
Example 5
1. Dispersing 4.5mL of ethyl orthosilicate in 45mL of ethanol to obtain a mixed solution 1; dispersing 0.35g of ammonium metatungstate and 3.834g of urea in 41mL of solvent consisting of ethanol and water (the volume ratio of the ethanol to the water is 16:25) to obtain a mixed solution 2, wherein the molar ratio of the added tungsten to the silicon is 1: 16; and quickly pouring the mixed solution 2 into the mixed solution 1, stirring at room temperature of 650r/min for 30min, carrying out hydrothermal reaction at 200 ℃ for 12h to obtain colloidal precipitate, filtering, washing the precipitate with water to be neutral, and drying at 60 ℃ to obtain the tungsten silicide/silicon dioxide composite precursor.
2. Taking 1g of tungsten silicide/silicon dioxide composite precursor powder, mixing with 10g of sodium chloride, adding 0.9g of metal magnesium powder, placing in a sealed tube furnace, heating to 400 ℃ at the speed of 5 ℃/min under the argon atmosphere, preserving heat for 0.5h, heating to 700 ℃ at the speed of 5 ℃/min, preserving heat for 10h, treating the cooled product in 1mol/L hydrochloric acid for 6h, filtering, washing to be neutral, and drying at the temperature of 60 ℃ to obtain the tungsten silicide/nano silicon particle composite material.
In the tungsten silicide/nano-silicon composite material prepared in this example, WSi2The mass fraction of (A) is 0.89%; the average particle diameter of the composite material is 46nm, the average particle diameter of the silicon particles is 40nm, the thickness of the tungsten silicide coating layer is 3nm, and the specific surface area of the composite material is 168m2 g-1。
The composite material prepared by the embodiment, conductive carbon black and sodium alginate are prepared into slurry according to the mass ratio of 6:2:2, the slurry is coated on a copper foil, and the lithium ion battery negative plate is prepared after drying for 12 hours at 60 ℃. A button cell CR2025 is used as a simulation cell, a metal lithium sheet is used as a counter electrode, and the electrolyte component is 1MLiPF6(ethylene carbonate: diethyl carbonate ═ 1:1, v/v), septum Celgard2400, and assembly was completed in a glove box filled with argon atmosphere. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The first reversible specific capacity of the battery can reach 1460mAh/g, and the reversible specific capacity after 200 cycles is 1210 mAh/g.
Example 6
1. Dispersing 4.5mL of ethyl orthosilicate in 45mL of ethanol to obtain a mixed solution 1; 0.74g of ammonium molybdate and 3.834g of urea are dispersed in 41mL of a solvent consisting of ethanol and water (the volume ratio of the ethanol to the water is 16:25) to obtain a mixed solution 2, wherein the molar ratio of the added molybdenum to the silicon element is 1: 4; and quickly pouring the mixed solution 2 into the mixed solution 1, stirring at room temperature of 650r/min for 30min, carrying out hydrothermal reaction at 200 ℃ for 12h to obtain colloidal precipitate, filtering, washing the precipitate with water to be neutral, and drying at 60 ℃ to obtain the molybdenum silicide/silicon dioxide composite precursor.
2. Taking 1g of molybdenum silicide/silicon dioxide composite precursor powder, mixing with 10g of sodium chloride, adding 0.9g of metal magnesium powder, placing in a sealed tube furnace, heating to 400 ℃ at the speed of 5 ℃/min under the argon atmosphere, preserving heat for 0.5h, heating to 700 ℃ at the speed of 5 ℃/min, preserving heat for 10h, treating the cooled product in 1mol/L hydrochloric acid for 6h, filtering, washing to be neutral, and drying at the temperature of 60 ℃ to obtain the molybdenum silicide/nano silicon particle composite material.
The molybdenum silicide/nano-silicon composite material prepared by the embodimentIn the material, MoSi2The mass fraction of (A) is 3.96%; the average particle diameter of the composite material is 52nm, the average particle diameter of the silicon particles is 41nm, the thickness of the molybdenum silicide coating layer is 5.5nm, and the specific surface area of the composite material is 182m2 g-1。
The composite material prepared by the embodiment, conductive carbon black and sodium alginate are prepared into slurry according to the mass ratio of 6:2:2, the slurry is coated on copper foil, and the lithium ion battery negative plate is prepared after drying for 12 hours at 60 ℃. A button cell CR2025 is used as a simulation cell, a metal lithium sheet is used as a counter electrode, and the electrolyte component is 1MLiPF6(ethylene carbonate: diethyl carbonate ═ 1:1, v/v), septum Celgard2400, and assembly was completed in a glove box filled with argon atmosphere. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The first reversible specific capacity of the battery can reach 1600mAh/g, and the reversible specific capacity is 1320mAh/g after 200 cycles of circulation.
Example 7
1. Dispersing 4.5mL of ethyl orthosilicate in 45mL of methanol to obtain a mixed solution 1; 0.69g of ammonium metatungstate and 3.834g of urea are dispersed in 41mL of a solvent consisting of methanol and water (the volume ratio of the methanol to the water is 16:25) to obtain a mixed solution 2, wherein the molar ratio of tungsten to silicon is 1: 4; and quickly pouring the mixed solution 2 into the mixed solution 1, stirring at room temperature of 650r/min for 30min, carrying out hydrothermal reaction at 200 ℃ for 12h to obtain colloidal precipitate, filtering, washing the precipitate with water to be neutral, and drying at 60 ℃ to obtain the tungsten silicide/silicon dioxide composite precursor.
2. Taking tungsten silicide/silicon dioxide composite precursor powder, mixing with 10g of sodium chloride, adding 0.9g of metal magnesium powder, placing in a sealed tubular furnace, heating to 400 ℃ at the speed of 5 ℃/min under the argon atmosphere, preserving heat for 0.5h, heating to 700 ℃ at the speed of 5 ℃/min, preserving heat for 10h, treating the cooled product in 1mol/L hydrochloric acid for 6h, filtering, washing to neutrality, and drying at the temperature of 60 ℃ to obtain the tungsten silicide/nano silicon composite material.
In the tungsten silicide/nano-silicon composite material prepared in this example, WSi2The mass fraction of (A) is 4.96%; of composite materialsThe average particle diameter is 52nm, the average particle diameter of the silicon particles is 41nm, the thickness of the tungsten silicide coating layer is 5.5nm, and the specific surface area of the composite material is 180m2 g-1。
The composite material prepared by the embodiment, conductive carbon black and sodium alginate are prepared into slurry according to the mass ratio of 6:2:2, the slurry is coated on copper foil, and the lithium ion battery negative plate is prepared after drying for 12 hours at 60 ℃. A button cell CR2025 is used as a simulation cell, a metal lithium sheet is used as a counter electrode, and the electrolyte component is 1MLiPF6(ethylene carbonate: diethyl carbonate ═ 1:1, v/v), septum Celgard2400, and assembly was completed in a glove box filled with argon atmosphere. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The first reversible specific capacity of the battery can reach 1880mAh/g, and the reversible specific capacity is 1400mAh/g after 200 cycles of circulation.
Example 8
1. Dispersing 4.5mL of ethyl orthosilicate in 45mL of ethanol to obtain a mixed solution 1; dispersing 1.03g of ammonium metatungstate and 4.86g of thiourea in 41mL of a solvent consisting of ethanol and water (the volume ratio of the ethanol to the water is 16:25) to obtain a mixed solution 2, wherein the molar ratio of the added tungsten to the silicon element is 1: 4; and quickly pouring the mixed solution 2 into the mixed solution 1, stirring at room temperature of 650r/min for 30min, carrying out hydrothermal reaction at 200 ℃ for 12h to obtain colloidal precipitate, filtering, washing the precipitate with water to be neutral, and drying at 60 ℃ to obtain the tungsten silicide/silicon dioxide composite precursor.
2. Taking 1g of tungsten silicide/silicon dioxide composite precursor powder, mixing with 10g of sodium chloride, adding 0.9g of metal magnesium powder, placing in a sealed tube furnace, heating to 400 ℃ at the speed of 5 ℃/min under the argon atmosphere, preserving heat for 0.5h, heating to 700 ℃ at the speed of 5 ℃/min, preserving heat for 10h, treating the cooled product in 1mol/L hydrochloric acid for 6h, filtering, washing to be neutral, and drying at the temperature of 60 ℃ to obtain the tungsten silicide/nano silicon composite material.
In the tungsten silicide/nano-silicon composite material prepared in this example, WSi2The mass fraction of (A) is 4.83%; the average particle diameter of the composite material is 64nm, the average particle diameter of the silicon particles is 52nm, and the tungsten silicide packageThe thickness of the coating was 6nm and the specific surface area of the composite material was 192m2 g-1。
And preparing the prepared tungsten silicide/nano silicon composite material, conductive carbon black and sodium alginate into slurry according to the mass ratio of 6:2:2, coating the slurry on copper foil, and drying at 60 ℃ for 12 hours to prepare the lithium ion battery negative plate. A button cell CR2025 is used as a simulation cell, a metal lithium sheet is used as a counter electrode, and the electrolyte component is 1MLiPF6(ethylene carbonate: diethyl carbonate ═ 1:1, v/v), septum Celgard2400, and assembly was completed in a glove box filled with argon atmosphere. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The first reversible specific capacity of the battery can reach 1950mAh/g, and the reversible specific capacity is 1450mAh/g after 200 cycles of circulation.
Example 9
1. Dispersing 4.5mL of ethyl orthosilicate in 45mL of ethanol to obtain a mixed solution 1; 0.49g of ammonium metavanadate and 3.39g of biuret are dispersed in 41mL of solvent consisting of ethanol and water (the volume ratio of the ethanol to the water is 10:25) to obtain a mixed solution 2, wherein the molar ratio of the added vanadium to the added silicon element is 1: 4; (ii) a And quickly pouring the mixed solution 2 into the mixed solution 1, stirring at the room temperature of 700r/min for 20min, carrying out hydrothermal reaction at 180 ℃ for 36h to obtain colloidal precipitate, filtering, washing the precipitate with water to be neutral, and drying at 70 ℃ to obtain the vanadium silicide/silicon dioxide composite precursor.
2. Mixing 1g of vanadium silicide/silicon dioxide composite precursor powder with 5g of sodium chloride, adding 2.0g of metal magnesium powder, placing the mixture in a sealed tubular furnace, heating to 350 ℃ at a speed of 5 ℃/min under the atmosphere of argon, preserving heat for 1h, heating to 600 ℃ at a speed of 5 ℃/min, preserving heat for 12h, treating the cooled product in 2.5mol/L hydrochloric acid for 6h, filtering, washing with water to be neutral, and drying at 60 ℃ to obtain the tungsten silicide/nano silicon composite material.
In the vanadium silicide/nano-silicon composite material prepared in this example, VSi2The mass fraction of (A) is 3.03%; the average particle diameter of the composite material is 52nm, the average particle diameter of the silicon particles is 43nm, the thickness of the tungsten silicide coating layer is 4.5nm, and the specific surface area of the composite material is177m2 g-1。
And (3) preparing the prepared composite material, conductive carbon black and sodium alginate into slurry according to the mass ratio of 6:2:2, coating the slurry on a copper foil, and drying at 60 ℃ for 12 hours to prepare the lithium ion battery negative plate. A button cell CR2025 is used as a simulation cell, a metal lithium sheet is used as a counter electrode, and the electrolyte component is 1MLiPF6(ethylene carbonate: diethyl carbonate ═ 1:1, v/v), septum Celgard2400, and assembly was completed in a glove box filled with argon atmosphere. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The first reversible specific capacity of the battery can reach 1870mAh/g, and the reversible specific capacity after 200 cycles is 1430 mAh/g.
Example 10
1. Dispersing 4.5mL of ethyl orthosilicate in 45mL of ethanol to obtain a mixed solution 1; 0.99g of ammonium molybdate and 3.834mol of urea are dispersed in 41mL of solvent consisting of ethanol and water (the volume ratio of the ethanol to the water is 11:25) to obtain a mixed solution 2, wherein the molar ratio of the added molybdenum to the silicon element is 1: 3; and quickly pouring the mixed solution 2 into the mixed solution 1, stirring for 30min at room temperature of 650r/min, carrying out hydrothermal reaction for 6h at 220 ℃ to obtain colloidal precipitate, filtering, washing the precipitate with water to be neutral, and drying at 60 ℃ to obtain the molybdenum silicide/silicon dioxide composite precursor.
2. Taking 1g of molybdenum silicide/silicon dioxide composite precursor powder, mixing with 5g of sodium chloride, adding 0.5g of metal magnesium powder, placing in a sealed tube furnace, heating to 450 ℃ at the speed of 5 ℃/min under the argon atmosphere, preserving heat for 3h, heating to 600 ℃ at the speed of 5 ℃/min, preserving heat for 4h, treating the cooled product in 2.5mol/L hydrochloric acid for 3h, filtering, washing to be neutral, and drying at the temperature of 60 ℃ to obtain the molybdenum silicide/nano silicon particle composite material.
In the molybdenum silicide/nano-silicon composite material prepared in this example, MoSi2The mass fraction of (A) is 8.97%; the average particle diameter of the composite material is 55nm, the average particle diameter of the silicon particles is 41nm, the thickness of the molybdenum silicide coating layer is 7nm, and the specific surface area of the composite material is 194m2 g-1。
Will make intoThe prepared composite material, conductive carbon black and sodium alginate are prepared into slurry according to the mass ratio of 6:2:2, the slurry is coated on copper foil, and the lithium ion battery negative plate is prepared after drying for 12 hours at the temperature of 60 ℃. A button cell CR2025 is used as a simulation cell, a metal lithium sheet is used as a counter electrode, and the electrolyte component is 1MLiPF6(ethylene carbonate: diethyl carbonate ═ 1:1, v/v), septum Celgard2400, and assembly was completed in a glove box filled with argon atmosphere. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The first reversible specific capacity of the battery can reach 1850mAh/g, and the reversible specific capacity is 1350mAh/g after 200 cycles of circulation.
Example 11
1. Dispersing 4.5mL of ethyl orthosilicate in 45mL of ethanol to obtain a mixed solution 1; dispersing 0.33g of ammonium metavanadate and 3.39g of biuret in 45mL of solvent consisting of ethanol and water (the volume ratio of the ethanol to the water is 10:25) to obtain a mixed solution 2, wherein the molar ratio of the added vanadium to the added silicon element is 1: 6; and quickly pouring the mixed solution 2 into the mixed solution 1, stirring at the room temperature of 700r/min for 20min, carrying out hydrothermal reaction at the temperature of 220 ℃ for 24h to obtain colloidal precipitate, filtering, washing the precipitate with water to be neutral, and drying at the temperature of 70 ℃ to obtain the vanadium silicide/silicon dioxide composite precursor.
2. Mixing 1g of vanadium silicide/silicon dioxide composite precursor powder with 15g of sodium chloride, adding 1g of metal magnesium powder, placing the mixture in a sealed tubular furnace, heating to 430 ℃ at a speed of 5 ℃/min under the argon atmosphere, preserving heat for 5h, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 6h, treating the cooled product in 2.0mol/L hydrochloric acid for 6h, filtering, washing with water to be neutral, and drying at 60 ℃ to obtain the tungsten silicide/nano silicon composite material.
In the vanadium silicide/nano-silicon composite material prepared in this example, VSi2The mass fraction of (A) is 2.12%; the average particle diameter of the composite material is 63nm, the average particle diameter of the silicon particles is 52nm, the thickness of the vanadium silicide coating layer is 5.5nm, and the specific surface area of the composite material is 174m2 g-1。
Preparing the prepared material, conductive carbon black and sodium alginate according to the mass ratio of 6:2:2And coating the slurry on a copper foil, and drying at 60 ℃ for 12h to prepare the lithium ion battery negative plate. A button cell CR2025 is used as a simulation cell, a metal lithium sheet is used as a counter electrode, and the electrolyte component is 1MLiPF6(ethylene carbonate: diethyl carbonate ═ 1:1, v/v), septum Celgard2400, and assembly was completed in a glove box filled with argon atmosphere. The prepared battery completes the charge and discharge test in a charge and discharge interval of 0.01-1.2V under the current density of 840 mAh/g. The first reversible specific capacity of the battery can reach 2200mAh/g, and the reversible specific capacity is 1550mAh/g after 200 cycles of circulation.
Compared with the material prepared in the comparative example 2, the material prepared in the example 1 has performance, the first reversible specific capacity is reduced, after the material is cycled for 200 circles, the reversible specific capacity of the comparative example 2 is reduced greatly, but the reversible specific capacity in the example 1 is relatively more stable.

Claims (9)

1. A method for preparing a dispersion distribution metal silicide/nano silicon composite material comprises the following steps:
1) preparing a composite precursor: dispersing metal oxolate, a silicon source and a solid ammonia source in a solvent, uniformly stirring, carrying out hydrothermal reaction under set conditions, and filtering, washing and drying after the reaction is finished to obtain a composite precursor;
2) preparing a composite material: uniformly mixing the composite precursor prepared in the step 1), reducing metal and metal chloride, performing two-stage heat treatment in a protective atmosphere, and after the treatment, performing acid washing, water washing, filtering and drying on a product to obtain a composite material;
the composite material consists of metal silicide and nano silicon particles, wherein part of the metal silicide is dispersed and distributed in the nano silicon, and the other part of the metal silicide is coated on the surfaces of the nano silicon particles; the composite material comprises 0.89-16.45% of metal silicide by mass and the balance of silicon.
2. The method for preparing the dispersion-distributed metal silicide/nano-silicon composite material according to claim 1, wherein the particle size of the nano-silicon particles is 5-100 nm, the particle size of the metal silicide dispersed in the nano-silicon particles is 0.1-10 nm, and the thickness of the metal silicide layer coated on the surface of the nano-silicon particles is 1-10 nm.
3. The preparation method of the dispersion distribution metal silicide/nano silicon composite material according to claim 1 or 2, wherein the specific surface area of the dispersion distribution metal silicide/nano silicon composite material is 10-500 m2 g-1。
4. The method for preparing the dispersion-distributed metal silicide/nano-silicon composite material according to claim 1, wherein in the step 1), the metal in the oxometallate is one of tungsten, molybdenum, niobium, tantalum and vanadium; the silicon source is one or more of sodium silicate, potassium silicate, ethyl orthosilicate and methyl orthosilicate, and the solid ammonia source is one or more of urea, thiourea, biuret, methylol urea, isobutyl diurea, urea formaldehyde and urea acetaldehyde; the solvent is a mixed solvent of water and alcohol, and the volume ratio of the water to the alcohol is 1: 0.02-20.
5. The method for preparing the dispersion-distributed metal silicide/nano-silicon composite material according to claim 4, wherein the metal oxolate is one of tungsten, molybdenum and vanadium; the silicon source is tetraethoxysilane; the solid ammonia source is urea.
6. The method of claim 5, wherein the oxometalate is one of ammonium metatungstate, ammonium molybdate and ammonium metavanadate.
7. The method for preparing the dispersion-distributed metal silicide/nano-silicon composite material according to claim 4, wherein the mass ratio of the metal oxolate, the silicon source and the solid ammonia source is 1 (2.2-18.3) to (2-12), and the mass-volume ratio of the metal oxolate to the mixed solvent is (0.25-1.40) to (85-91) g/mL; the hydrothermal reaction temperature is 180-220 ℃, and the reaction time is 6-48 h.
8. The method for preparing the dispersion-distributed metal silicide/nano-silicon composite material according to claim 1, wherein in the step 2), the reducing metal is one or more of lithium, sodium, potassium, calcium, zinc, magnesium and aluminum; the metal chloride salt is one or more of potassium chloride, sodium chloride, magnesium chloride, zinc chloride and aluminum chloride; the mass ratio of the composite precursor to the reducing metal to the metal chloride is 1: 0.5-2: 1-15.
9. The method for preparing the dispersion-distributed metal silicide/nano-silicon composite material according to claim 1, wherein in the step 2), the protective atmosphere is one or more of hydrogen, argon and helium; the two-stage heat treatment comprises a first-stage low-temperature pretreatment and a second-stage high-temperature reduction treatment; the low-temperature pretreatment temperature is 350-450 ℃, and the treatment time is 0.5-5 h; the high-temperature reduction treatment temperature is 600-800 ℃, and the treatment time is 1-12 h; the acid washing is carried out by adopting 0.5-2.5 mol/L hydrochloric acid.
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CN103682279A (en) * 2013-12-27 2014-03-26 浙江大学 Silicon-based composite lithium ion battery negative electrode material as well as preparation method and application of silicon-based composite lithium ion battery negative electrode material
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