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Method for preparing graphite-based Si@C negative electrode material by taking silica fume as Si source

A technology of anode material and micro-silica fume, which is applied in the field of preparing graphite-based Si@C anode materials, can solve the problems of no significant increase in theoretical specific capacity, low Si packing density, and complicated preparation process, etc. The effect of embedding depth, simple preparation process, and shortened diffusion distance

Inactive Publication Date: 2021-05-07
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the preparation process is complex, costly and harmful to the environment, and cannot be commercialized; another solution is to coat the outside of Si with a carbon layer with a radius larger than Si particles, giving Si enough room for expansion, but in this way As a result, the packing density of Si is not high, and the theoretical specific capacity has not been greatly improved.

Method used

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  • Method for preparing graphite-based Si@C negative electrode material by taking silica fume as Si source
  • Method for preparing graphite-based Si@C negative electrode material by taking silica fume as Si source
  • Method for preparing graphite-based Si@C negative electrode material by taking silica fume as Si source

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Embodiment 1

[0026] A method for preparing a graphite-based Si@C negative electrode material using microsilica powder as a Si source, specifically comprising the following steps:

[0027] (1) Raise the original micro-silicon powder in a muffle furnace at a rate of 3°C / min to 700°C for 4 hours, then disperse it in a HCl solution with a concentration of 3.26mol / L, heat it in a water bath at 60°C and stir it dynamically for 1 hour, then Raise the temperature to 90°C and stir for 4 hours, filter with suction, wash with water, and dry to obtain a pretreated sample.

[0028] (2) Mix the pretreated sample with magnesium powder with a particle size of 5 μm at a mass ratio of 1:0.85, use n-pentane as the medium, and use a planetary ball mill for mixing at a speed of 200 rpm. The ball milling time was 24 hours, and the reaction material sample was obtained after natural drying.

[0029] (3) Put the reaction material in a sealed graphite crucible, and in a tube furnace with Ar: increase the temperat...

Embodiment 2

[0038] A method for preparing a graphite-based Si@C negative electrode material using microsilica powder as a Si source, specifically comprising the following steps:

[0039] (1) Raise the original micro-silicon powder in a muffle furnace at 3°C / min to 600°C for 10 hours, then disperse it in an HCl solution with a concentration of 2mol / L, heat it in a water bath at 60°C and stir for 1 hour, then raise the temperature Stir at 90°C for 4 hours, filter with suction, wash with water, and dry to obtain a pretreated sample.

[0040] (2) Mix the pretreated sample and magnesium powder with a particle size of 150 μm at a mass ratio of 1:1, use n-pentane as the medium, and use a planetary ball mill for mixing at a speed of 150 rpm. The ball milling time was 48h, and the reaction material sample was obtained after natural drying.

[0041] (3) Put the reaction material in a sealed graphite crucible, and in a tube furnace with Ar: raise the temperature from room temperature to 300°C at a ...

Embodiment 3

[0046] A method for preparing a graphite-based Si@C negative electrode material using microsilica powder as a Si source, specifically comprising the following steps:

[0047] (1) Raise the original micro-silicon powder in a muffle furnace at 2°C / min to 750°C for 4 hours, then disperse it in a HCl solution with a concentration of 5mol / L, heat it in a water bath at 60°C and stir for 1 hour, then raise the temperature Stir at 90°C for 4 hours, filter with suction, wash with water, and dry to obtain a pretreated sample.

[0048] (2) Mix the pretreated sample and magnesium powder with a particle size of 100 μm at a mass ratio of 1:0.9, use n-pentane as the medium, and use a planetary ball mill for mixing at a speed of 150 rpm. The ball milling time was 24 hours, and the reaction material sample was obtained after natural drying.

[0049] (3) Put the reaction material in a sealed graphite crucible, and in a tube furnace with Ar: heat up from room temperature to 700°C at a rate of 2...

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Abstract

The invention discloses a method for preparing a graphite-based Si@C negative electrode material by taking micro-silicon powder as a Si source. The method comprises the following steps: pretreating the micro-silicon powder, then carrying out ball-milling mixing and reduction reaction on the micro-silicon powder and magnesium powder, and carrying out acid pickling and centrifugal drying to obtain porous crystal Si particles; and uniformly mixing the prepared porous crystal Si with dopamine in a prepared Tris buffer solution with the pH value of 8.5 to deposit polydopamine on the surfaces of Si particles, and coating the Si to prepare the composite material with the Si-C core-shell structure. The composite material has excellent electrochemical performance, relatively high specific capacity, long cycle life, high capacity retention ratio and stable cycle life; the pore structure of the carbon layer and the Si particles wrapped by the carbon layer also shortens the diffusion distance and time for deintercalation and intercalation of lithium ions; the conductivity of Si is enhanced by the coating carbon layer; and the Si@C core-shell structure also prevents the electrolyte from being in direct contact with Si to form an unstable SEI film.

Description

technical field [0001] The invention relates to a method for preparing a graphite-based Si@C negative electrode material by using micro-silicon powder as a Si source, and belongs to the technical field of silicon-carbon composite material preparation. Background technique [0002] Due to the high energy storage density and long cycle life of lithium-ion batteries, they have been widely used in electric vehicles, energy storage devices and various portable electronic products. However, the theoretical specific capacity of graphite materials commonly used in lithium-ion battery negative electrodes is low, only 372mAh∙g -1 , the rate performance is poor, which can no longer meet the current demand for lithium-ion batteries. Therefore, exploring and developing electrodes with high specific capacity has become an urgent problem to be solved. Si is the most potential next-generation high-capacity anode material, and its theoretical specific capacity can reach 4200mAh∙g -1 It is...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/583H01M4/62H01M10/0525
CPCH01M4/366H01M4/386H01M4/625H01M4/583H01M10/0525Y02E60/10
Inventor 盛婉婷郭玉忠李昆儒李朕宇
Owner KUNMING UNIV OF SCI & TECH
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