阅读说明：本技术 一种三维枝晶多孔硅的制备方法及其应用 (Preparation method and application of three-dimensional dendritic crystal porous silicon ) 是由 许荣福 孔凡涛 李彦 许广池 李常厚 时月亚 徐勇 *** 于 2019-11-01 设计创作，主要内容包括：本发明提供了一种三维枝晶多孔硅的制备方法及其应用,属于多孔硅制备领域。其技术方案为：所述制备方法包括以下步骤：S1、前驱体合金制备；S2、将步骤S1得到的厚度为5μm~500μm的前驱体合金置于腐蚀液进行脱合金处理,得到脱合金试样；S3、后续处理得到三维微/纳米枝晶结构多孔硅材料。本发明的有益效果为：本发明的采用生产常用的铸造铝硅合金作为原材料,大幅降低生产成本,同时可解决粉末材料难以控制前驱体合金金相组织,进而调控最终制备多孔硅材料结构形貌这一难题；该发明中所述的前驱体合金组织调控及试验条件容易控制,可解决了低成本储能的产业化瓶颈问题,具有良好的商业化前景。(The invention provides a preparation method and application of three-dimensional dendritic crystal porous silicon, and belongs to the field of porous silicon preparation. The technical scheme is as follows: the preparation method comprises the following steps: s1, preparing a precursor alloy; s2, placing the precursor alloy with the thickness of 5-500 mu m obtained in the step S1 in corrosive liquid for dealloying treatment to obtain a dealloying sample; and S3, carrying out subsequent treatment to obtain the porous silicon material with the three-dimensional micro/nano dendritic structure. The invention has the beneficial effects that: according to the invention, the casting aluminum-silicon alloy commonly used for production is adopted as a raw material, so that the production cost is greatly reduced, and the problem that the metallographic structure of the precursor alloy is difficult to control by using the powder material, and the structural morphology of the finally prepared porous silicon material is further regulated and controlled can be solved; the precursor alloy structure regulation and test conditions are easy to control, the industrial bottleneck problem of low-cost energy storage can be solved, and the method has good commercialization prospect.)

1. A preparation method of three-dimensional dendritic porous silicon is characterized by comprising the following steps:

s1, preparing a precursor alloy: taking a proper amount of aluminum-silicon alloy, carrying out melt blending on the aluminum-silicon alloy by using melting equipment to obtain liquid aluminum-silicon alloy, carrying out proper melt treatment on the obtained liquid aluminum-silicon alloy, then regulating and controlling the cooling speed of the melt and pouring to obtain a sample, and carrying out treatment on the obtained sample by adopting linear cutting and pre-grinding by a pre-grinder to obtain a precursor alloy with the thickness of 5-500 mu m;

s2, placing the precursor alloy with the thickness of 5-500 mu m obtained in the step S1 in corrosive liquid for dealloying treatment to obtain a dealloying sample;

s3, subsequent processing: and (5) repeatedly washing the dealloying sample obtained in the step (S2) for 100-300S by using deionized water, then putting the dealloying sample into absolute ethyl alcohol, cleaning for 6-15 min by using ultrasonic waves to remove residual other impurity attachments, and finally putting the sample in a wet state into a vacuum drying oven to be dried for 5-10 h to obtain the three-dimensional micro/nano dendritic crystal structure porous silicon material.

2. The method for producing porous silicon according to claim 1, wherein the aluminum-silicon alloy in step S1 is a binary aluminum-silicon alloy or a multi-component aluminum-silicon alloy, and the aluminum-silicon alloy is a bulk or rod-like sample.

3. The method for preparing porous silicon according to claim 2, wherein the binary aluminum-silicon alloy contains silicon 5.0-30.0 wt% and aluminum in balance.

4. The method for preparing porous silicon according to claim 2, wherein the mass content of silicon in the multi-element aluminum-silicon alloy is 5.0-30.0%, the mass content of the added alloy elements is 1.0-10.0%, and the balance is aluminum; the added alloy elements are one or the combination of more than two of the following elements: copper element, iron element, magnesium element, chromium element, nickel element, manganese element, zinc element, zirconium element, titanium element, lithium element, silver element, vanadium element, cerium element, lanthanum element, yttrium element and niobium element.

5. The method for preparing porous silicon according to claim 1, wherein the etching solution in step S1 is an acidic solution or an alkaline solution, the acidic solution is hydrochloric acid, sulfuric acid or nitric acid, and the alkaline solution is sodium hydroxide or potassium hydroxide.

6. The preparation method of the porous silicon according to claim 1, wherein the three-dimensional dendritic porous silicon material prepared by the preparation method can be applied to preparation of porous silicon composite materials, super capacitors and energy storage devices with high specific capacity.

Technical Field

The invention relates to the field of preparation of porous silicon, in particular to a preparation method of three-dimensional dendritic crystal porous silicon.

Background

With the development of clean energy technologies and industries such as solar energy, wind energy and the like, the development of low-cost high-capacity energy storage technologies is urgently needed. Compared with the traditional lead-acid battery, nickel-metal hydride battery and other batteries, the secondary energy storage device represented by the lithium ion battery and the like is widely applied due to the advantages of high working voltage, high energy density, light weight, no memory effect, strong adaptability to high and low temperature, environmental protection and the like. Graphite is the most commercially successful negative electrode material for energy storage devices, but the theoretical specific capacity of the graphite material is 372mAh g ^-1The energy density is not yet satisfactory. At present, the theoretical specific capacity of silicon is up to 4200mAh g in all known negative electrode materials ^-1Meanwhile, the silicon also has the advantages of lower lithium intercalation potential, rich reserves, low price, environmental friendliness and the like. Silicon is therefore considered to be one of the most promising and potential replacements for conventional graphite anodes.

The biggest disadvantage of silicon is the rapid decay in cycle capacity and service life due to the volume expansion of up to 300% during the li/li insertion/extraction process. In order to solve the problems of volume expansion, poor cycle performance and the like of silicon, a porous structure is introduced into the silicon negative electrode material, so that the volume expansion stress can be buffered, the contact site with electrolyte can be increased, the capacity of the electrolyte can be improved, and the like. Therefore, many researches are carried out at home and abroad aiming at the preparation of porous silicon and relevant researches, and the commonly used preparation method and process comprise the following steps: a magnesiothermic reduction method, a metal-assisted chemical etching method, a template method, a chemical reaction-followed etching method, a dealloying method, and the like.

The domestic patents CN201310122811.4, CN2015109222810, CN2016105470638, CN2016110399407, CN2016104453917, CN2017102423470 and the like disclose the preparation method of porous silicon. However, the raw materials adopted by the preparation method of the porous silicon material are alloy powder or pure metal powder materials, and the defects are that the powder material is high in price and uneven in granularity, and the metallographic structure of the powder material and the morphological structure of the subsequently prepared porous silicon material are difficult to regulate and control.

Disclosure of Invention

The invention aims to provide a method for preparing porous silicon material by using casting aluminum-silicon alloy which is commonly used for production as a raw material, so that the production cost is greatly reduced, and the problem that the metallographic structure of a precursor alloy is difficult to control by a powder material, and the structural morphology of the finally prepared porous silicon material is further regulated and controlled is solved; the precursor alloy structure regulation and test conditions are easy to control, the industrial bottleneck problem of low-cost energy storage can be solved, and the preparation method of the three-dimensional dendritic crystal porous silicon has good commercial prospect.

The invention is realized by the following measures:

a preparation method of three-dimensional dendritic porous silicon is characterized by comprising the following steps:

s1, preparing a precursor alloy: taking a proper amount of aluminum-silicon alloy, carrying out melt blending on the aluminum-silicon alloy by using melting equipment to obtain liquid aluminum-silicon alloy, carrying out proper melt treatment on the obtained liquid aluminum-silicon alloy, then regulating and controlling the cooling speed of the melt and pouring to obtain a sample, wherein the metallographic structure of the sample contains micro/nano silicon phase particles, and carrying out treatment on the obtained sample by adopting linear cutting and pre-grinding by a pre-grinder to obtain a precursor alloy with the thickness of 5-500 mu m;

s2, placing the precursor alloy with the thickness of 5-500 mu m obtained in the step S1 in corrosive liquid for dealloying treatment to obtain a dealloying sample;

s3, subsequent processing: and (5) repeatedly washing the dealloying sample obtained in the step (S2) for 100-300S by using deionized water, then putting the dealloying sample into absolute ethyl alcohol, cleaning for 6-15 min by using ultrasonic waves to remove residual other impurity attachments, and finally putting the sample in a wet state into a vacuum drying oven to be dried for 5-10 h to obtain the three-dimensional micro/nano dendritic crystal structure porous silicon material.

The invention has the following specific characteristics:

the aluminum-silicon alloy in the step S1 is binary aluminum-silicon alloy or multi-component aluminum-silicon alloy, and the aluminum-silicon alloy is a block-shaped or rod-shaped sample.

The binary aluminum-silicon alloy is characterized in that the mass content of silicon is 5.0-30.0%, and the balance is aluminum.

In the multi-element aluminum-silicon alloy, the mass content of silicon is 5.0-30.0%, the mass content of the added alloy elements is 1.0-10.0%, and the balance is aluminum; the added alloy elements are one or the combination of more than two of the following elements: copper element, iron element, magnesium element, chromium element, nickel element, manganese element, zinc element, zirconium element, titanium element, lithium element, silver element, vanadium element, cerium element, lanthanum element, yttrium element and niobium element.

The three-dimensional dendritic crystal porous silicon material prepared by the preparation method can be applied to porous silicon composite material preparation, super capacitors and energy storage devices with high specific capacity.

The corrosive solution in the step S1 is an acidic solution or an alkaline solution, the acidic solution is hydrochloric acid, sulfuric acid or nitric acid, and the alkaline solution is sodium hydroxide or potassium hydroxide.

The melt treatment in the step S1 is refining treatment of primary aluminum in the aluminum-silicon alloy, and modification inoculation treatment of primary silicon or eutectic silicon.

The step S1 of regulating the cooling speed of the melt refers to the control of the solidification conditions of the aluminum-silicon alloy, i.e., the ordinary cooling at room temperature or the water chilling condition or the liquid nitrogen cooling or the single-roller rotary quenching cooling is adopted.

The principle of the invention is as follows: the dealloying treatment means that the potential difference between each element or each phase of the composition alloy is large, the relatively active alloy elements are dissolved away through chemical or electrochemical action, and the rest inert elements form a three-dimensional porous structure through atomic diffusion and self-recombination action. The invention relates to a method for preparing a three-dimensional porous silicon material by using an aluminum-silicon alloy melt as a precursor alloy and then by using a dealloying method, wherein the aluminum-silicon alloy melt is subjected to modification/refinement/inoculation treatment and solidification speed joint regulation and control. For aluminum-silicon alloy, the standard electrode potential manual is inquired to determine that the hydrogen standard potential of aluminum is-1.676V (active chemical property), the hydrogen standard potential of silicon is-0.143V (inactive chemical property), and a large electrode potential difference exists between aluminum and silicon, so that the condition of dealloying is met.

The structure of the porous silicon can be controlled by:

firstly, the aluminum-silicon alloy is regulated and controlled by melt treatment and other technologies, so that the alloy metallographic structure contains uniform micro/nano silicon phase particles, namely the alloy is subjected to melt treatment to achieve the purpose of regulating and controlling the morphology of the porous silicon structure;

and secondly, in the multi-element aluminum-silicon alloy, the purpose of regulating and controlling the morphology of the porous silicon is achieved by the atomic diffusion, atomic self-recombination and atomic replacement of the removal element and the silicon element in the process of dealloying.

The invention has the beneficial effects that: the three-dimensional dendritic crystal porous silicon can be applied to the preparation of porous silicon composite materials, supercapacitors and energy storage devices with high specific capacity, and more importantly, the production cost can be greatly reduced because the casting aluminum-silicon alloy commonly used for production is adopted as a raw material instead of the aluminum-silicon alloy powder material used in powder metallurgy; meanwhile, the problem that the metallographic structure of the precursor alloy is difficult to control by the powder material, and the structural morphology of the finally prepared porous silicon material is regulated and controlled is solved; the precursor alloy structure regulation and test conditions are easy to control, the industrial bottleneck problem of low-cost energy storage can be solved, and the method has good commercialization prospect.

Drawings

FIG. 1 is a diagram of a porous silicon material obtained in example 2 of the present invention.

FIG. 2 is an XRD pattern analysis of porous silicon obtained in example 3 of the present invention.

FIG. 3 is a graph of the morphology of porous silicon obtained in example 4 of the present invention.

FIG. 4 is a graph of the morphology of porous silicon obtained in example 5 of the present invention.

FIG. 5 is a graph showing the morphology of porous silicon obtained in example 6 of the present invention.

Detailed Description

In order to clearly illustrate the technical features of the present solution, the present solution is explained below by way of specific embodiments.