Porous silicon carbon composite material and preparation method therefor

A carbon composite material and porous silicon technology, applied in the field of nanomaterials, can solve the problems of affecting the rate charge and discharge performance, large volume change, capacity attenuation of silicon anode materials, etc.

Active Publication Date: 2016-01-06
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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  • Claims
  • Application Information

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Problems solved by technology

However, on the one hand, the volume change of the silicon material is relatively large (~300%) during the process of lithium intercalation and deintercalation, and the structural stability is poor, which easily leads to the failure of the electrode material to pulverize and fall off, resulting in serious capacity attenuation of the silicon negative electrode material.
On the other hand, the conductivity of silicon is poor, which affects its rate charge and discharge performance.

Method used

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  • Porous silicon carbon composite material and preparation method therefor
  • Porous silicon carbon composite material and preparation method therefor
  • Porous silicon carbon composite material and preparation method therefor

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preparation example Construction

[0106] Specifically, the preparation method of the present invention comprises steps:

[0107] (1) Provide a silicon-active metal alloy;

[0108] (2) reacting the alloy with a liquid phase pore-forming agent to remove the active metal to obtain a porous silicon nanomaterial;

[0109] (3) cleaning the porous silicon nanomaterial with a hydrofluoric acid solution to remove silicon oxide, and obtaining a porous silicon nanomaterial cleaned with hydrofluoric acid;

[0110] (4) mixing the obtained nano-silicon material with the polymer and ball milling to obtain a homogeneous mixture of porous nano-silicon / polymer;

[0111] (5) Calcining the nano-silicon / polymer mixture to obtain a porous silicon-carbon composite material.

[0112] In another preferred embodiment, the above-mentioned polymer is added in a liquid form (such as suspension, dispersion, etc.).

[0113] In another preferred example, the silicon-active metal alloy is silicon-active metal alloy scrap. The silicon-acti...

Embodiment 1

[0165] First, the aluminum-silicon alloy ingot (such as figure 1 ) crushed and ground into debris of 0.1mm to 100mm, then 20g of aluminum silicon alloy debris with a diameter of 0.1mm to 100mm (such as figure 2 ), slowly added to 270ml of 5% dilute hydrochloric acid solution to react, magnetically stirred evenly. After the mixed solution is fully reacted, the mixed solution is filtered and rinsed with deionized water and ethanol to remove AlCl 3 Porous silicon nanoparticles are obtained; then the porous silicon nanoparticles are added to a 5% mass ratio of hydrofluoric acid solution for cleaning, after the surface of the porous silicon nanoparticles or excess silicon oxide have been removed, filter and fully rinse with deionized water and ethanol , to collect porous nano-silicon with single composition and relatively uniform morphology, such as image 3 .

[0166] After porous nano-silicon is mixed with polyacrylonitrile, carry out ball milling (wet milling), ball milling ...

Embodiment 2

[0171] First, the aluminum-silicon alloy ingot (such as figure 1 ) crushed and ground into chips of 0.1 mm to 100 mm, 50 g of aluminum silicon alloy chips with a diameter of 0.1 mm to 100 mm were slowly added to 480 ml of 10% dilute hydrochloric acid solution for reaction, and magnetically stirred evenly. After the mixed solution is fully reacted, the mixed solution is filtered and rinsed with deionized water and ethanol to remove AlCl 3 Porous silicon nanoparticles are obtained; then the porous silicon nanoparticles are added to a 5% mass ratio of hydrofluoric acid solution for cleaning, after the surface of the porous silicon nanoparticles or excess silicon oxide have been removed, filter and fully rinse with deionized water and ethanol , Porous nano-silicon with single composition and relatively uniform morphology was collected.

[0172] After porous nano-silicon is mixed with polyacrylonitrile, ball milling (wet milling) is carried out. Ball milling equipment: Germany Lai...

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Abstract

The invention provides a porous silicon carbon composite material and a preparation method therefor. The method specifically comprises the steps of (1) providing silicon-active metal alloy; (2) performing reaction between the alloy and a liquid phase pore forming agent to remove the active metal so as to obtain a porous silicon nanometer material; (3) cleaning the porous silicon nanometer material by a hydrofluoric acid solution so as to remove silicon oxide and thus to obtain a porous silicon nanometer material being cleaned by the hydrofluoric acid; (4) mixing the obtained nano-silicon material with a polymer, and then performing ball milling to obtain a porous nano-silicon/polymer uniform mixture; and (5) calcining the nano-silicon/polymer uniform mixture to obtain the porous silicon-carbon composite material. The preparation method can effectively control the proportion of the silicon element to the carbon element in the silicon carbon composite material; and when the prepared material is used as the negative electrode active material for lithium ion batteries, the lithium ion batteries are high in cycling stability and coulombic efficiency.

Description

technical field [0001] The invention relates to the field of nanometer materials, in particular, the invention provides a porous silicon / carbon negative electrode material, a preparation method thereof, and an application thereof in a lithium ion battery. Background technique [0002] With the rapid development of mobile electronic devices, people put forward higher requirements on the performance of chemical power sources. Due to its advantages of large specific energy, high cell voltage and low self-discharge, high-power lithium-ion batteries have become the focus and hot spot of research and development in countries all over the world. At the same time, lithium-ion batteries also have problems such as safety, high cost, and reduced cycle life. Therefore, how to effectively improve the safety, cycle life, energy density and reduce the cost of lithium-ion batteries has become the key to the development of lithium-ion battery technology. As an important factor to improve b...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/587H01M4/38H01M4/133H01M4/134H01M10/0525
CPCY02E60/10
Inventor 田华军韩伟强
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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