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Preparation method of porous silicon

A technology of porous silicon and porous electrodes, which is applied in chemical instruments and methods, electrolytic processes, surface etching compositions, etc., can solve the problems of high cost and achieve the effects of recycling, easy scale-up production, and easy-to-obtain raw materials

Inactive Publication Date: 2019-05-17
CHINA AUTOMOTIVE BATTERY RES INST CO LTD
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  • Abstract
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Problems solved by technology

[0004] Aiming at the above problems, the present invention provides a method for preparing porous silicon, which uses silicon dioxide powder as a raw material and prepares porous silicon material by electrolysis in calcium chloride molten salt, thereby solving the existing problem of preparing porous silicon. The problem of high cost of raw materials and catalysts used in the method reduces the overall cost of porous silicon preparation. At the same time, the method has simple process flow, easy operation, and is convenient for mass production

Method used

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Examples

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Embodiment 1

[0026] Put 0.5g of silica powder (D50=30nm) into a cylindrical compression molding die with a diameter of 20mm, and press the above powder into a diameter of 20mm, A thin sheet with a thickness of about 2mm is sintered in a muffle furnace at 900°C in an air atmosphere for 5 hours to obtain a porous silicon dioxide electrode; the porous electrode is wound and bound with a molybdenum wire as a cathode, and LiCl:KCl at 600°C :CaCl 2 The mixed molten salt of 53.4:11.6:35mol% is used as the electrolyte, graphite is used as the anode, and a constant voltage of 1.8V is applied between the anode and cathode for electrolysis, and the electrolysis power is controlled to reduce the silicon dioxide in the porous electrode to silicon. 1.5 times (the formula for calculating the amount of electricity required to reduce silica to silicon is: mass of silica (unit: g)÷molecular weight of silica (60.084)×4×Faraday constant (96485.3C / mol)); electrolysis is completed Finally, the cathode is taken...

Embodiment 2

[0028]7.5kg of silica powder (D50=30nm) and 7.5kg of graphite powder (D50=3.5μm) were evenly mixed by planetary agitation, then put into an isostatic bag, and formed by isostatic pressing (forming pressure 185Mpa, Pressing time 10 minutes) Press the above powder into a green body, and cut it into thin slices of 100×100×5 mm, sinter the above thin slices in a muffle furnace at 1150° C. in an air atmosphere for 1 hour, to obtain a silicon dioxide porous electrode; The above-mentioned porous electrode is wrapped with foamed nickel and compressed with a perforated stainless steel plate as the cathode, with 850°C calcium chloride molten salt as the electrolyte, graphite as the anode, and a constant current of 10A is applied between the cathode and the anode for electrolysis. Control the electrolysis power to be twice the power required to reduce silicon dioxide to silicon in the porous electrode (the calculation formula for the power required to reduce silicon dioxide to silicon is:...

Embodiment 3

[0034] 7.5kg of silica powder (D50=30nm) and 7.5kg of graphite powder (D50=3.5μm) were evenly mixed by planetary agitation, then put into an isostatic pressing bag, and formed by isostatic pressing (forming pressure 100Mpa, Pressing time 1 minute) Press the above-mentioned powder into a green body, and cut it into thin slices of 100×100×5mm, and sinter the above-mentioned thin slices in a muffle furnace at 1150° C. in an air atmosphere for 1 hour to obtain a silicon dioxide porous electrode; The above-mentioned porous electrode is wrapped with foamed nickel and compressed with a perforated stainless steel plate as the cathode, with 850°C calcium chloride molten salt as the electrolyte, graphite as the anode, and a constant current of 10A is applied between the cathode and the anode for electrolysis. Control the electrolysis power to be twice the power required to reduce silicon dioxide to silicon in the porous electrode (the calculation formula for the power required to reduce ...

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Abstract

The invention relates to a preparation method of porous silicon, and belongs to the technical field of material preparation. The method comprises the steps as follows: performing pressing formation onsilicon dioxide powder for preparation of blocks, and performing sintering forming to obtain a porous electrode; wrapping and pressing the porous electrode by a porous conductive material to serve asa cathode, or winding and binding the porous electrode by a metal wire to serve as a cathode, and performing electrolysis with molten salt containing calcium chloride as an electrolyte and graphite as an anode; washing an electrolytic product with a hydrochloric acid solution and treating the product with a hydrofluoric acid solution to obtain a porous silicon material. Continuous electrolysis can be realized by replacing the cathode, and the morphology and composition ratio of silicon / calcium silicide electrolysis products can be controlled by controlling molten salt temperature, electrolysis process parameters, electrolysis electric quantity and the like, so that the morphology of porous silicon can be conveniently regulated and controlled; recycling of calcium chloride can be realized;the method has the advantages that raw materials are cheap and easily available, reaction temperature is relatively low, the morphology of porous silicon is easy to adjust, production can be enlargedconveniently and the like.

Description

technical field [0001] The invention belongs to the technical field of material preparation, and in particular relates to a preparation method of a porous silicon material. Background technique [0002] Porous silicon has the characteristics of high porosity, high specific surface area, and photoluminescence, and has important application value in the fields of photocatalysis, photoelectrochemical water splitting, supercapacitors, biosensing, and lithium-ion batteries. When applied to lithium-ion battery anode materials, porous silicon not only has the advantages of high specific capacity and low delithiation potential of conventional silicon materials, but its special porous structure can effectively alleviate the huge volume change of silicon during charging and discharging, which is beneficial to improve The cycle performance of the silicon anode material prolongs its service life. In recent years, the urgent requirement of the new energy automobile industry for high-ene...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25B1/00C09K13/08
Inventor 齐小鹏杨娟玉卢世刚王宁张杰赵立川余章龙史碧梦
Owner CHINA AUTOMOTIVE BATTERY RES INST CO LTD
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