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Zinc-bismuth alloy-coated silicon-magnesium particles prepare foamy silicon powder and silicon powder

A bismuth alloy, foam-like technology is applied in the field of preparation of foamed silicon powder, which can solve the problems of difficult to control the particle size of nano-silicon powder, low powder preparation efficiency, difficult control, etc. Burning problem, uniform effect of micropore voids

Active Publication Date: 2019-05-07
GUILIN ELECTRICAL EQUIP SCI RES INST
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  • Summary
  • 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 and overburning of the processed powder, thereby bringing Due to the rapid growth of silicon particles and the oxidation of silicon, it is very difficult to control the process of industrially producing porous nano-silicon powder with this method, especially difficult to control the particle size of nano-silicon powder; the prior art also discloses a method using metal chloride molten salt The medium is kept warm for a long time (10h~15h) to decompose silicon-magnesium alloy powder, and then pickled with hydrochloric acid to obtain porous silicon. This method eliminates the risk of magnesium ignition and combustion in industrial production, but the process requires long-term heat preservation, and there is a powder preparation efficiency. low problem

Method used

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  • Zinc-bismuth alloy-coated silicon-magnesium particles prepare foamy silicon powder and silicon powder
  • Zinc-bismuth alloy-coated silicon-magnesium particles prepare foamy silicon powder and silicon powder
  • Zinc-bismuth alloy-coated silicon-magnesium particles prepare foamy silicon powder and silicon powder

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preparation example Construction

[0068] 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.

[0069] 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 size of the micropores is 5 nm to 100 nm. The primary particle size is less than 120nm. The smaller the particle size of the primary p...

Embodiment 1

[0075] (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;

[0076] (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;

[0077] (3) select particle size to be 20-300 purpos...

Embodiment 2

[0088] (1)(2) is identical with embodiment one;

[0089] (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 preferably consists of 50 grams of metal zinc powder and metal bismuth with a particle size of less than 100 mesh 950 grams of powder are mixed, the above-mentioned silicon-magnesium alloy powder and coated metal powder are put into a stainless steel tank with a diameter of 185mm, and cemented carbide balls that are 2-4 times the weight of the above-mentioned mixed powder are added. The diameter is 6-12mm, and it is filled with nitrogen or argon to protect the seal, and the usual rolling ball mill is used for mixing and ball milling for 36 hours;

[0090] (4) same as embodiment one;

[0091] (5) same as embodiment one;

[0092] (6) The obtained powder after the diffusion heat treatment is packed into a tubular vacuum furnace, and t...

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Abstract

The invention discloses a method for preparing foamed silicon powder by using zinc-bismuth alloy to coat silicon magnesium particles. The method comprises the following steps: preparing silicon magnesium alloy powder; coating the surface of the silicon magnesium alloy powder with a zinc bismuth alloy layer; conducting solid-phase diffusion heat treatment on the silicon-magnesium alloy powder coated with the zinc bismuth alloy layer to promote zinc and bismuth metals in the coating layer to react with magnesium silicon correspondingly; conducting oxidation treatment on the silicon magnesium alloy powder subjected to the solid-phase diffusion heat treatment; conducting acid pickling on the silicon magnesium alloy powder subjected to the oxidation treatment to remove the zinc, the bismuth andmagnesium. By adopting the zinc bismuth alloy not easily oxidized and having a melting point lower than the ignition point of the magnesium to coat the silicon magnesium alloy particles, solid phasediffusion treatment and a low-oxygen oxidation treatment process at a certain temperature are used to obtain the foamed silica powder with a micropore structure. Efficiency of preparation is improvedand primary particle size of the foamed silicon powder is smaller.

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 zinc-bismuth 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 c...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/021H01M4/62B82Y30/00
CPCB82Y30/00C01B33/021H01M4/62Y02E60/10
Inventor 朱凌云王振宇何旻雁刘鑫雨张天锦
Owner GUILIN ELECTRICAL EQUIP SCI RES INST
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