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Method for preparing foamy silicon powder by coating silicon and magnesium particles with tin-indium alloy and silicon powder

A tin-indium alloy, foam-like technology, which is applied in the field of foamed silicon powder preparation, can solve the problems of difficulty in controlling the particle size of nano-silicon powder, easy to catch fire, burn and oxidize, low powder preparation efficiency, etc. The effect of low overall oxygen content and high crystallinity

Active Publication Date: 2019-09-06
GUILIN ELECTRICAL EQUIP SCI RES INST
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the process of synthesizing silicon-magnesium alloy powder, because a large amount of magnesium powder is used, the production process must have strict environmental control measures such as helium protection to reduce the risk of explosion of magnesium dust; , the temperature of the bismuth melt needs to be above 450°C, that is, the temperature is about 150°C higher than the ignition point of magnesium (300°C). Magnesium at such a temperature is very easy to ignite, burn, and oxidize, causing high-temperature spontaneous combustion of the treated powder, thereby bringing silicon The rapid growth of particles and the oxidation of silicon, so it is very difficult to control the process of industrial production of porous nano-silicon powder by this method, especially the particle size of nano-silicon powder is difficult to control; Time heat preservation (10h~15h) method to decompose silicon-magnesium alloy powder, and then obtain porous silicon by hydrochloric acid pickling. This method eliminates the risk of magnesium ignition and combustion in industrial production, but the process requires long time heat preservation, and there is a problem of low powder preparation efficiency. question

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  • Method for preparing foamy silicon powder by coating silicon and magnesium particles with tin-indium alloy and silicon powder
  • Method for preparing foamy silicon powder by coating silicon and magnesium particles with tin-indium alloy and silicon powder
  • Method for preparing foamy silicon powder by coating silicon and magnesium particles with tin-indium alloy and silicon powder

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preparation example Construction

[0067] The preparation method of the embodiment of the present invention is not limited to the smelting, mixing and ball milling, heat treatment, and pickling methods described above, and can also be completed by methods known to those skilled in the art, and the ball milling medium in the powder crushing process is not limited to asphalt Acetone solution, asphalt tetrahydrofuran solution, polyvinyl alcohol aqueous solution and PI / NMP solution, organic polymer compounds known to those skilled in the art can also be added to obtain a certain carbon conductive layer on the surface of silicon powder.

[0068] According to another aspect of the embodiments of the present invention, there is also provided a foamed silicon powder, which includes silicon powder particles, the silicon powder particles have a plurality of microporous structures, and the micropore size is 3 nm to 500 nm. The primary particle size is less than 200nm. The smaller the particle size of the primary particles...

Embodiment 1

[0074] (1) Choose a small intermediate frequency vacuum smelting furnace, according to the capacity of the smelting graphite crucible, prepare silicon blocks and magnesium blocks at a ratio of 1 kg per furnace, containing 30-35% silicon (mass percentage), and put the ingredients in the argon atmosphere. Silicon and a small amount of massive magnesium are melted. While controlling the temperature of the melt at 1100-1200°C during the smelting process, the remaining metal magnesium blocks are added step by step. After the final heat preservation for 2-5 minutes, pour into the furnace at 250-300°C Preheated cast iron molds to obtain silicon-magnesium alloy ingots;

[0075] (2) Take out the cooled silicon-magnesium alloy ingot, coarsely crush it with a jaw crusher until the particle size is less than 5mm in a dry air atmosphere, vibrate and ball mill it under the protection of a nitrogen atmosphere, and then sieve and classify;

[0076] (3) Select silicon-magnesium alloy powder wi...

Embodiment 2

[0086] (1)(2) is identical with embodiment one;

[0087] (3) The preferred particle size is 200 grams of silicon-magnesium alloy powder of 100-200 mesh, equipped with 1000 grams of coated metal powder in a ratio of 1:5, and the coated metal powder is preferably made of a tin-indium alloy with a particle size of less than 100 mesh containing 25% tin powder, put the above-mentioned silicon-magnesium alloy powder and coated metal powder into a stainless steel tank with a diameter of 185mm, and mix in cemented carbide balls 2-4 times the weight of the above-mentioned mixed powder. The diameter of the cemented carbide ball is 6.12mm. And fill it with nitrogen or argon to protect the seal, and use a common rolling ball mill to mix and mill for 32 hours;

[0088] (4) same as embodiment one;

[0089] (5) same as embodiment one;

[0090] (6) The obtained powder after the diffusion heat treatment is packed into a tubular vacuum furnace, and the oxygen content is 5-20% (volume ratio), ...

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Abstract

The invention discloses a method for preparing foam-shaped silicon powder by using silicon magnesium particles coated with tin indium alloy. The method comprises the steps that silicon magnesium alloypowder is prepared; the surface of the silicon magnesium alloy powder is coated with a tin indium alloy layer; the silicon magnesium alloy powder coated with the tin indium alloy layer is subjected to solid-phase diffusion heat treatment, so that the situation is promoted that metal tin and indium in the coating layer react with and are combined with magnesium and silicon respectively; the silicon magnesium alloy powder after subjected to the solid-phase diffusion heat treatment is subjected to oxidation treatment; the silicon magnesium alloy powder after subjected to oxidation treatment is subjected to acid washing, and tin, indium and magnesium are removed. The tin indium alloy which is not easily oxidized and has the melting point lower than the magnesium fire point is adopted for coating the silicon magnesium alloy particles, by combining with solid-phase diffusion treatment and low-oxygen oxidation treatment technologies at a certain temperature, the foam silicon powder with a micropore structure is obtained, the preparation efficiency is improved, and the primary granularity of the foam silicon powder is small.

Description

technical field [0001] The invention relates to a method for preparing foamy silicon powder, in particular to a method for preparing foamy silicon powder by coating silicon-magnesium particles with a tin-indium alloy, and also to a foamy silicon powder prepared by the method. Background technique [0002] Since silicon has a theoretical specific capacity (4200mAh / g) more than ten times higher than that of graphite anode, the use of silicon to replace the commonly used graphite anode has become the goal of high energy density power battery research. As a negative electrode, silicon has the disadvantages of large volume expansion, silicon particle breakage, pulverization, low coulombic efficiency for the first charge and discharge, and high impedance; in response to the above shortcomings, a series of improvement methods have been proven effective, such as the use of nanoscale silicon particles It can reduce the breakage of bulk silicon, the use of porous silicon particles can...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/021H01M4/62
CPCC01B33/021C01P2004/62C01P2006/12C01P2006/16H01M4/625Y02E60/10
Inventor 朱凌云王振宇汪英赵霞妍何旻雁
Owner GUILIN ELECTRICAL EQUIP SCI RES INST
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