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A nitrogen-doped porous nanosheet silicon-carbon composite material and its preparation method and application

A technology of silicon-carbon composite materials and nanosheets, applied in structural parts, electrical components, battery electrodes, etc., can solve problems such as capacity fading, failure to fundamentally suppress charge and discharge volume effects, and easy aggregation of nanoparticles

Active Publication Date: 2021-01-12
SHAANXI UNIV OF SCI & TECH
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Problems solved by technology

Although the above method alleviates the capacity decay of the material to a certain extent, the nanoparticles are easy to agglomerate, so the volume effect during the charge and discharge process cannot be fundamentally suppressed, and the capacity will still decay rapidly with the increase in the number of cycles.

Method used

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  • A nitrogen-doped porous nanosheet silicon-carbon composite material and its preparation method and application
  • A nitrogen-doped porous nanosheet silicon-carbon composite material and its preparation method and application
  • A nitrogen-doped porous nanosheet silicon-carbon composite material and its preparation method and application

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preparation example Construction

[0028] A preparation method of nitrogen-doped porous nano-sheet silicon-carbon composite material: add soluble organic matter as carbon source in a closed container, then add ammonium chloride, and finally add silicon dioxide to stir and disperse, and perform hydrothermal reaction at 100-250°C for 2- After 24 hours, the precursor was obtained by drying, and an appropriate amount of magnesium powder was added to the precursor to be calcined and reduced at 650-750°C, and finally washed and etched with hydrofluoric acid to obtain a nitrogen-doped porous nanosheet silicon-carbon composite material.

[0029] The preparation method of described silica is as follows:

[0030] Mix absolute ethanol, water, and ammonia water, stir at 25°C for 30 minutes, quickly add tetraethyl orthosilicate, continue stirring, centrifuge, wash with water, wash with alcohol, and dry to obtain silica nanospheres with a particle size of 200-300nm.

[0031] The preferred temperature of the above-mentioned h...

Embodiment 1

[0041] Dissolve 5g of glucose and 5g of ammonium chloride in 70ml of water, then stir thoroughly with 1g of silicon dioxide, transfer the mixture to a closed reaction kettle, and react at 220°C for 3.5h. After the reaction is completed, the precursor is obtained by drying. Add magnesium powder, the mass of which is 1 times the mass of the precursor, grind evenly, and calcinate at 650°C for 10h under an argon atmosphere, then stir in 1M HCl for 2 hours to remove impurities, wash, filter and dry with a mass fraction of 2%. HF etching for 6h, washing and drying to obtain a silicon-carbon composite material, the powder diffraction pattern is shown in figure 1 , as seen from the powder diffraction pattern, the three peaks at 28.6, 47.4, and 56.3 degrees correspond to (111), (200), (311) crystal planes of cubic Si (JCPDS 27-1402). At 35.6, 60.0, 71.8, the corresponding peaks are SiC peaks, and the peaks at 18.0, 26.9, 42.8, 62.1 degrees correspond to C peaks. figure 2 In a, b and...

Embodiment 2

[0045] 5.5g of sucrose and 4.5g of ammonium chloride were dissolved in 70ml of water, then 1.2g of silicon dioxide was stirred thoroughly, the mixture was transferred to a closed reaction kettle, and reacted at 200°C for 4h. After the reaction is completed, the precursor is obtained by drying. Add magnesium powder, the mass of which is 1.5 times the mass of the precursor, grind evenly, and calcinate at 690°C for 6h under an argon atmosphere, then stir in 1M HCl for 2 hours to remove impurities, wash, filter and dry with a mass fraction of 0.5% HF etching for 10 hours, washing and drying to obtain a silicon-carbon composite material to obtain a silicon-carbon composite material.

[0046] Mix the obtained silicon-carbon composite material with acetylene black and polyvinylidene fluoride in a mass ratio of 8:1:1, and smear it on a copper foil to assemble a button battery as the negative electrode material of a lithium-ion battery. The electrolyte is LiPF 6 (1mol / L):EC:DMC=1:1:1...

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Abstract

The invention provides a nitrogen-doped porous nanosheet silicon carbon composite material and a preparation method and application thereof. The method comprises the steps of: adding a soluble organicsubstance as a carbon source to a closed container; then adding ammonium chloride; finally adding silica to stir and disperse the mixture; performing a hydrothermal reaction at 100 to 250 degrees centigrade for 2 to 24 hours; drying the product to obtain a precursor; adding an appropriate amount of magnesium powder to the precursor; calcining and reducing the mixture at 650 to 750 degrees centigrade; and finally obtaining the nitrogen-doped porous nanosheet silicon carbon composite material as the negative electrode material of a battery by washing and hydrofluoric acid etching. The method ofthe invention has simple process and low energy consumption in a preparation process. The nitrogen-doped porous nanosheet silicon carbon composite material prepared by the method has distinct structural features, is in a porous nanosheet shape, and has large specific area, distinct structural features and excellent electrochemical performance. The negative electrode material assembled from the silicon-carbon composite material prepared by the method has excellent electrochemical performance.

Description

technical field [0001] The invention relates to the technical field of silicon-carbon composite materials, in particular to a nitrogen-doped porous nanosheet silicon-carbon composite material and a preparation method and application thereof. Background technique [0002] Energy is the basis for human survival and development. Traditional energy sources such as coal, oil, and natural gas are facing problems such as declining reserves and environmental pollution, and cannot meet future social needs. Lithium-ion batteries have the characteristics of high operating voltage, high energy density, long cycle life, low self-discharge rate and no pollution, and are considered to be ideal energy storage and conversion tools. At present, it is widely used in various portable electric tools and digital electronic products. As people continue to pursue the functions of electronic products, further improving the energy density of lithium-ion batteries has become a research hotspot. [0...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/364H01M4/38H01M4/386H01M4/625H01M10/0525Y02E60/10
Inventor 郭守武宋佳佳郑鹏刘毅张利锋原晓艳霍京浩寇领江
Owner SHAANXI UNIV OF SCI & TECH
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