1. An apparatus for producing porous silicon powder, comprising:

electrochemical corrosion of the cell: electrochemical corrosion liquid is contained;

a cathode assembly: the electrochemical corrosion device comprises a cathode fixing frame fixed on the inner wall of the electrochemical corrosion tank, a cathode sheet which is arranged on the cathode fixing frame and the bottom end of which can be immersed in electrochemical corrosion liquid, and a cathode power line which is connected with the cathode sheet and is used for electrically connecting an external power supply cabinet;

an anode box: including install be the outer support frame of square frame form on the electrochemical corrosion groove inner wall, set up on the outer support frame inboard and as the box body spare of positive pole, and connect the positive pole power cord of box body spare, box body spare comprises the preceding box piece and the back box piece of airtight foraminiferous, preceding box piece and back box piece interval set up on the outer support frame and form confined box body cavity with outer support frame, still embedded have the breather pipe that stretches into the box body cavity on the outer support frame.

2. The apparatus of claim 1, wherein an anode box locking column is vertically disposed on the inner wall of the electrochemical etching cell, and the anode box is slidably mounted on the anode box locking column.

3. The apparatus of claim 1, wherein the outer support frame and the vent tube further have vent holes with a diameter of 1 μm;

the diameter of the holes on the front box piece and the rear box piece is 0.5 mu m;

the cathode plate, the front box plate and the rear box plate are all platinum plates.

4. The apparatus for preparing porous silicon powder as claimed in claim 1, wherein the outer support frame is further provided with a pull tab at the top end thereof;

the box body piece is also provided with a zipper opening which can be opened and closed.

5. A method for producing porous silicon powder, which is carried out by using the production apparatus according to any one of claims 1 to 4, characterized by comprising the steps of:

(1) taking a silicon source and putting HCl and H₂O₂Soaking in the mixed solution, filtering and washing to obtain a product A;

(2) placing the product A in SnCl₂Soaking the mixture in a mixed solution of HCl, and taking out to obtain a product B;

(3) soaking the product B in a metal deposition solution, and taking out to obtain a product C;

(4) and placing the product C in an anode box, adding an electrochemical corrosion solution into an electrochemical corrosion tank, introducing oxygen into a vent pipe, switching on a power supply, carrying out electrochemical corrosion treatment, and finally taking out, cleaning and drying to obtain the target product.

6. The method according to claim 5, wherein in the step (1), the silicon source is one or more of monocrystalline silicon powder, polycrystalline silicon powder or silica powder, and the average diameter of the silicon source is 1-50 μm;

the concentration of HCl in the mixed solution is 0.5-5mol/L, H₂O₂The concentration of (A) is 0.5-6 mol/L;

the soaking time is 0.5-5 h.

7. The method according to claim 5, wherein in step (2), SnCl is added₂The concentration of the HCl is 0.001-0.1mol/L, the concentration of the HCl is 1-10mol/L, and the soaking time is 1-30 min.

8. The method according to claim 5, wherein in step (3), the metal deposition solution contains a surface modifier and a metal salt, wherein,

the surface modifier is one or more of sodium acetate, sodium alginate, cellulose, citric acid or sodium phosphate, and the concentration of the surface modifier is 0.1-20 g/L;

the metal salt is AgNO₃、NiCl₂、FeCl₃、NiSO₄、CuCl₂Or CuSO₄The concentration of one or more of the above-mentioned materials is 0.001-0.1 mol/L.

9. The method according to claim 5, wherein in the step (4), the electrochemical etching solution is a mixed solution of anhydrous ethanol and one of inorganic acid or inorganic base, wherein the inorganic acid is one or more of hydrochloric acid, sulfuric acid and nitric acid, the inorganic base is one of sodium hydroxide or potassium hydroxide, and the concentrations of the inorganic acid, the inorganic base and the anhydrous ethanol are all 0.01-5 mol/L.

10. The method according to claim 5, wherein in the step (4), the flow rate of the oxygen gas is 50-500ml/min, and the current is 10-200mA/cm²。

Background

The porous silicon has large specific surface area and is commonly used in a plurality of fields such as optics, photoelectronics, biopharmaceuticals, sensors, new energy and the like. Silicon, as a lithium battery negative electrode material, has an extremely high lithium storage capacity (4200mAh/g), but has a large volume effect during the lithium deintercalation process. The porous structure of porous silicon provides a buffer space for lithium intercalation expansion of silicon, and thus has attracted much attention and has been studied. At present, the preparation method of porous silicon mainly comprises a dealloying method, a chemical corrosion method, a hydrothermal corrosion method, a steam etching method, a double-groove electrochemical method, a single-groove electrochemical method, a galvanic couple method and the like. However, the dealloying method, the chemical etching method and the hydrothermal etching method have long period and many side reactions, the pore channel distribution of the prepared porous silicon is difficult to control, and hydrofluoric acid which is extremely harmful to human bodies needs to be used. For example, Park et Al (Hyeong-Il Park, Myungbeom Sohn, Dae Sik Kim, et Al. Carbon Nanofiber/3D Nanoporus Silicon Hybrids as High Capacity Silicon Storage Materials [ J ] ChemSusChem,2016, 9(8)) use Si/Al-Cu-Fe as a raw material and prepare porous Silicon by a dealloying method, which requires 24h of soaking in hydrochloric acid. The existing double-groove electrochemical method, single-groove electrochemical method and galvanic couple method need the silicon source and the electrode to be tightly combined, and can only prepare massive porous silicon and cannot prepare porous silicon powder. For example, (Shuangzhen, Huming, Wei, etc., research on porous silicon preparation by galvanic corrosion method [ J ] materials engineering, 2006(11)), after a silicon wafer and a blocky electrode are combined, blocky porous silicon can be prepared in mixed electrolyte of hydrofluoric acid and hydrogen peroxide, expensive metal salt and high-concentration hydrofluoric acid are needed for preparing porous silicon powder by a metal ion auxiliary etching method, the high-concentration hydrofluoric acid is volatile, the porous silicon powder has irreversible harm to the skin, respiratory tract and even bones of a human body, strict protection and waste liquid treatment facilities are needed for use, and the industrial use difficulty is high.

Therefore, the current industrial preparation of porous silicon powder, in particular to nano-porous silicon powder used for the negative electrode of a lithium ion battery, is difficult to meet the market demand. The present invention has been made to solve the above problems.

Disclosure of Invention

The present invention aims to overcome the defects of the prior art and provide a preparation device and a preparation method of porous silicon powder.

The purpose of the invention can be realized by the following technical scheme:

one of the technical schemes of the invention provides a preparation device of porous silicon powder, which comprises the following components:

electrochemical corrosion of the cell: electrochemical corrosion liquid is contained;

a cathode assembly: the electrochemical corrosion device comprises a cathode fixing frame fixed on the inner wall of the electrochemical corrosion tank, a cathode sheet which is arranged on the cathode fixing frame and the bottom end of which can be immersed in electrochemical corrosion liquid, and a cathode power line which is connected with the cathode sheet and is used for electrically connecting an external power supply cabinet;

an anode box: including install be the outer support frame of square frame form on the electrochemical corrosion groove inner wall, set up on the outer support frame inboard and as the box body spare of positive pole, and connect the positive pole power cord of box body spare, box body spare comprises the preceding box piece and the back box piece of airtight foraminiferous, preceding box piece and back box piece interval set up on the outer support frame and form confined box body cavity with outer support frame, still embedded have the breather pipe that stretches into the box body cavity on the outer support frame.

Furthermore, an anode box clamping column is vertically arranged on the inner wall of the electrochemical corrosion tank, and the anode box is slidably mounted on the anode box clamping column.

Furthermore, the outer support frame and the vent pipe are also sealed with vent holes with the aperture of 1 μm.

Furthermore, the diameter of the holes on the front box piece and the back box piece is 0.5 μm.

Furthermore, a handle is arranged at the top end of the outer support frame.

Furthermore, the box body piece is also provided with a zipper opening which can be opened and closed.

Furthermore, the cathode plate, the front box plate and the rear box plate are all platinum plates.

The box body part is prepared by adopting a porous platinum sheet, the electrochemical corrosion liquid can freely flow inside and outside the cavity of the box body, the current can flow onto the platinum sheet through the anode power supply wire, and the oxidizing gas introduced into the vent pipe helps the silicon source to be oxidized on one hand, and on the other hand, the silicon source of the box body continuously moves and rolls, so that the powdered silicon source in the box body can contact the box body part to be quickly oxidized and corroded.

The second technical scheme of the invention provides a preparation method of porous silicon powder, which is implemented with the assistance of the preparation device and comprises the following steps:

(1) taking a silicon source and putting HCl and H₂O₂Soaking in the mixed solution, filtering and washing to obtain a product A;

(2) placing the product A in SnCl₂Soaking the mixture in a mixed solution of HCl, and taking out to obtain a product B;

(3) soaking the product B in a metal deposition solution, and taking out to obtain a product C;

(4) and placing the product C in an anode box, adding an electrochemical corrosion solution into an electrochemical corrosion tank, introducing oxygen into a vent pipe, switching on a power supply, carrying out electrochemical corrosion treatment, and finally taking out, cleaning and drying to obtain the target product.

Further, in the step (1), the silicon source is one or more of monocrystalline silicon powder, polycrystalline silicon powder or silicon monoxide powder, and the average diameter of the silicon source is 1-50 μm.

Further, in the step (1), the concentration of HCl in the mixed solution is 0.5-5mol/L, and H₂O₂The concentration of (B) is 0.5-6 mol/L.

Further, in the step (1), the soaking time is 0.5-5 h.

Further, in the step (2), SnCl₂The concentration of the HCl is 0.001-0.1mol/L, the concentration of the HCl is 1-10mol/L, and the soaking time is 1-30 min.

Further, in the step (3), the metal deposition solution contains a surface modifier and a metal salt, preferably, the surface modifier is one or more of sodium acetate, sodium alginate, cellulose, citric acid or sodium phosphate, and the concentration of the surface modifier is more preferably 0.1-20 g/L;

preferably, the metal salt is AgNO₃、NiCl₂、FeCl₃、NiSO₄、CuCl₂Or CuSO₄More preferably, the concentration of one or more of the above is 0.001-0.1 mol/L.

Further, the electrochemical corrosion solution is a mixed solution of one of inorganic acid or inorganic base and absolute ethyl alcohol, wherein the inorganic acid is one or more of hydrochloric acid, sulfuric acid and nitric acid, the inorganic base is one of sodium hydroxide or potassium hydroxide, and the concentrations of the inorganic acid, the inorganic base and the absolute ethyl alcohol are all 0.01-5 mol/L.

Further, the flow rate of the introduced oxygen is 50-500ml/min, and the current is 10-200mA/cm²。

In the invention, step (1) is to remove the impurity ion effect of the silicon source and oxidize the surface of the silicon source a little, step (2) is a silicon source sensitizing process, the surface of the silicon source is roughened through step (1) and step (2), the silicon source is soaked in the low-concentration metal deposition liquid in step (3) to enable metal to be uniformly deposited on the surface of the silicon source for nucleation and growth, in the subsequent electrochemical corrosion process, the metal uniformly deposited on the surface of the silicon source provides an electron fast channel to cause differential corrosion on the surface of the silicon source, oxygen is led to the silicon source through a vent hole to promote the oxidation corrosion of the silicon source, meanwhile, the silicon source is continuously rolled and uniformly to contact a box body, the electron is rapidly transferred through metal particles, in the electrochemical corrosion liquid containing inorganic acid, the silicon source existing around the metal particles and water rapidly react to form silicic acid to be dissolved, in the electrochemical corrosion liquid containing inorganic base, the silicon source existing around the metal particles reacts with the alkali quickly to generate silicate, so that under the action of promoting corrosion of the metal particles uniformly deposited on the surface of the silicon source, the corrosion speeds of a metal covered area and an uncovered area on the surface of the silicon source are differentiated to form a porous structure with uniformly distributed pore channels.

In the present inventionSnCl in step (2) and step (3)₂The metal deposition, reduction and nucleation growth on the surface of the silicon source are promoted by the action of the surface modifier, and the concentration is too low (SnCl)₂<0.001mol/L of surfactant<0.1g/L) may cause insufficient metal deposition on the surface of the silicon source and may cause the pores of the prepared porous silicon powder to be too small. Excessive concentration (SnCl)₂>0.0010.1 mol/L surfactant>20g/L), a layer of metal can be deposited on the surface of the silicon source without distinction, and porous silicon can not be prepared through subsequent electrochemical corrosion. Also, the concentration of the metal salt in the step (3) is too low (<0.001mol/L) fails to deposit enough metal on the surface of the silicon source, resulting in too small pore size and too large concentration of metal salt in the prepared porous silicon (>0.1mol/L) can cause a layer of metal to be deposited on the surface of the silicon source without difference, differential corrosion can not be formed in the subsequent electrochemical corrosion process, and porous silicon can not be prepared. Too high concentration of the inorganic acid or the inorganic base can cause a large amount of corrosion of the silicon source to form small-size submicron silicon or nano silicon, and too low concentration can not corrode the silicon source and can not prepare porous silicon.

Compared with the prior art, the invention does not use high-concentration hydrofluoric acid which is volatile and has irreversible harm to the skin, respiratory tract and even bones of a human body in the preparation process. The preparation method is characterized in that a simple electrochemical corrosion method and a metal auxiliary etching method are adopted, equipment and method are improved, the electrochemical corrosion of the powder silicon source is realized to prepare the porous silicon powder, the preparation time is short, the prepared porous silicon has uniformly distributed pore channels, the pore channel diameter is controllable, and the method is suitable for industrial production.

Drawings

FIG. 1 is a schematic diagram of the structure of a cathode assembly and an electrochemical corrosion cell;

FIG. 2 is a schematic structural view of an anode case;

FIG. 3 is a scanning electron micrograph of the porous silicon powder prepared in example 3;

in the figure: 1-cathode fixing frame, 2-cathode power line, 3-anode box clamping column, 4-electrochemical corrosion tank, 5-outer supporting frame, 6-box body, 7-zipper, 8-vent pipe, 9-anode power line and 10-handle.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention will be described in detail and completely with reference to the accompanying drawings 1, 2 and preparation steps of the present invention, and it is to be understood that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

Referring to fig. 1 and 2, the present invention provides an apparatus for preparing porous silicon powder comprising; the cathode assembly comprises a cathode platinum sheet and a cathode fixing frame 1, the top end of the cathode platinum sheet is fixedly connected with the cathode fixing frame 1, a cathode power supply wire hole is arranged on the cathode fixing frame 1, a cathode power supply wire 2 is arranged at the top end of the cathode platinum sheet, the cathode platinum sheet is electrically connected with an external power supply cabinet (which can adopt the model DPH-20/800) through the cathode power supply wire 2, the cathode platinum sheet is electrically connected with an external power supply cabinet through the cathode power supply wire 2, the cathode fixing frame 1 is fixedly connected with the electrochemical corrosion tank 4, an anode box clamping column 3 is arranged at the anode end of the electrochemical corrosion tank 4, the anode box is slidably connected with the electrochemical corrosion tank 4 through the anode box clamping column 3, the anode box comprises an outer supporting frame 5 and a box body part 6, the box body part 6 is provided with a front box sheet and a rear box sheet, the platinum sheets with a large number of holes are made, and the diameters of the holes are 0.5 mu m respectively, the front box piece, the rear box piece and the outer support frame 5 form a closed space which can be communicated with electrochemical corrosion electrolyte to ensure the transmission of current and electrons and ensure that a silicon source does not leak, a vent pipe 8 is embedded in the outer support frame 5, a large number of vent holes with the diameter of 1 mu m are arranged on the inner sides of the outer support frame 5 and the vent pipe 8, an anode power supply wire hole is arranged on the outer support frame 5, an anode power supply wire 9 is arranged at the top end of the box body piece 6, the box body piece 6 is electrically connected with a DPH-20/800 power supply cabinet through the anode power supply wire 9, a handle 10 is arranged at the top end of the outer support frame 5, the box body piece 6 is fixedly connected with the inner side of the outer support frame 5, and a zipper 7 is arranged on the box body piece 6.

The following are examples of porous silicon powder production using the above production apparatuses, respectively.

Example 1:

in conjunction with the preparation apparatus, the specific preparation steps of this example are as follows

Step one, 10g of single crystal silicon powder with the grain diameter of 1 mu m is put into 0.5mol/L HCl and 0.5mol/L H₂O₂Soaking the mixed solution for 0.5h, filtering and then washing by adopting deionized water to obtain a product A;

step two, putting the product A into 0.001mol/L SnCl₂Soaking the mixture in a mixed solution of HCl of 1mol/L for 1min, and filtering to obtain a product B;

thirdly, putting the product B into 0.1g/L sodium acetate, 0.1g/L sodium alginate, 0.1g/L citric acid and 0.001mol/L NiSO₄Soaking the mixed solution for 10min, and filtering to obtain a product C;

fourthly, the zipper 7 is unzipped to place the product C into the anode box, the zipper 7 is closed, the anode box containing the product C is in sliding connection with the electrochemical corrosion tank 4 through the anode box clamping column 3, 0.01mol/L hydrochloric acid and 0.01mol/L absolute ethyl alcohol are added into the electrochemical corrosion tank 4, oxygen is introduced into the vent pipe at the flow rate of 50ml/min, the cathode and the anode box are respectively and electrically connected with the DPH-20/800 power cabinet through the cathode power line 2 and the anode power line 9, the switch of the DPH-20/800 power cabinet is opened, and 10mA/cm is switched on²And (3) carrying out current and electrochemical corrosion for 10min, taking out the box body part 6 through the handle 10, cleaning the box body part with deionized water, and drying to obtain a porous silicon powder product D, wherein the pore diameter is 5-50nm, and the porosity is 17%.

Example 2:

in conjunction with the preparation apparatus, the specific preparation steps of this example are as follows

Step one, 50g of polycrystalline silicon powder with the grain diameter of 3 mu m is put into 0.8mol/L HCl and 0.7mol/L H₂O₂Soaking the mixed solution for 1h, filtering and then washing by adopting deionized water to obtain a product A;

step two, putting the product A into 0.003mol/L SnCl₂Soaking the mixture in a mixed solution of HCl of 2mol/L for 10min, and filtering to obtain a product B;

thirdly, putting the product B into 0.2g/L sodium acetate, 0.1g/L sodium phosphate, 0.5g/L citric acid and 0.005mol/L NiSO₄Soaking the mixed solution for 10min, and filtering to obtain a product C;

fourthly, the zipper 7 is unzipped to place the product C into the box body part 6, the zipper 7 is closed, the anode box containing the product C is in sliding connection with the electrochemical corrosion tank 4 through the anode box clamping column 3, 0.02mol/L potassium hydroxide and 0.01mol/L absolute ethyl alcohol are added into the electrochemical corrosion tank 4, oxygen is introduced into the vent pipe at the flow rate of 100ml/min, the cathode and the anode box are respectively and electrically connected with the DPH-20/800 power cabinet through the cathode power line 2 and the anode power line 9, the switch of the DPH-20/800 power cabinet is opened, and 50mA/cm is switched on²And (3) carrying out current and electrochemical corrosion for 20min, taking out the anode box through the handle 10, cleaning the anode box by using deionized water, and drying to obtain a porous silicon powder product D, wherein the pore diameter is 200-500nm, and the porosity is 48%.

Example 3:

in conjunction with the preparation apparatus, the specific preparation steps of this example are as follows

Step one, 200g of silica with the particle size of 5 mu m is put into 1mol/L HCl and 2mol/L H₂O₂Soaking the mixed solution for 1h, filtering and then washing by adopting deionized water to obtain a product A;

step two, putting the product A into 0.005mol/L SnCl₂Soaking the mixture in a mixed solution of HCl of 2mol/L for 15min, and filtering to obtain a product B;

thirdly, putting the product B into 0.4g/L sodium acetate, 0.5g/L sodium phosphate, 1g/L citric acid and 0.01mol/L CuSO₄Soaking the mixed solution for 20min, and filtering to obtain a product C; (ii) a

Fourthly, the zipper 7 is unzipped to place the product C into the box body part 6, the zipper 7 is closed, the anode box containing the product C is in sliding connection with the electrochemical corrosion tank 4 through the anode box clamping column 3, 0.02mol/L hydrochloric acid and 1mol/L absolute ethyl alcohol are added into the electrochemical corrosion tank 4, oxygen is introduced into the vent pipe at the flow rate of 100ml/min, the cathode and the anode box are respectively and electrically connected with the DPH-20/800 power cabinet through the cathode power line 2 and the anode power line 9, the switch of the DPH-20/800 power cabinet is opened, and 100mA/cm is switched on²And (3) carrying out current and electrochemical corrosion for 20min, taking out the anode box through the handle 10, cleaning the anode box by using deionized water, and drying to obtain a porous silicon powder product D, wherein the pore diameter is 40-200nm, the porosity is 26%, and the porous silicon pore channel distribution is dense and uniform as can be obviously seen from figure 3.

Example 4:

in conjunction with the preparation apparatus, the specific preparation steps of this example are as follows

Step one, 30kg of silicon monoxide with the grain diameter of 5 mu m is put into 1mol/L HCl and 2mol/L H₂O₂Soaking the mixed solution for 1h, filtering and then washing by adopting deionized water to obtain a product A;

step two, putting the product A into 0.01mol/L SnCl₂Soaking the mixture in a mixed solution of HCl of 2mol/L for 20min, and filtering to obtain a product B;

step three, putting the product B into 1g/L sodium acetate, 5g/L sodium phosphate, 2g/L citric acid and 0.05mol/L AgNO₃Soaking the mixed solution for 30min, and filtering to obtain a product C;

fourthly, the zipper 7 is unzipped to place the product C into the box body part 6, the zipper 7 is closed, the anode box containing the product C is in sliding connection with the electrochemical corrosion tank 4 through the anode box clamping column 3, 0.05mol/L sodium hydroxide and 1mol/L absolute ethyl alcohol are added into the electrochemical corrosion tank 4, oxygen is introduced into the vent pipe at the flow rate of 100ml/min, the cathode and the anode box are respectively and electrically connected with the DPH-20/800 power cabinet through the cathode power line 2 and the anode power line 9, the switch of the DPH-20/800 power cabinet is opened, and 100mA/cm is switched on²And (3) carrying out current and electrochemical corrosion for 20min, taking out the anode box through the handle 10, cleaning the anode box by using deionized water, and drying to obtain a porous silicon powder product D, wherein the pore diameter is 200-400nm, and the porosity is 31%.

Example 5:

in conjunction with the preparation apparatus, the specific preparation steps of this example are as follows

Step one, 50kg of silicon monoxide with the grain diameter of 50 mu m is put into 5mol/L HCl and 6mol/L H₂O₂Soaking the mixed solution for 5 hours, filtering and then washing by adopting deionized water to obtain a product A;

step two, putting the product A into 0.1mol/L SnCl₂Soaking the mixture in a mixed solution of 10mol/L HCl for 30min, and filtering to obtain a product B;

thirdly, putting the product B into 20g/L sodium acetate, 20g/L sodium phosphate, 20g/L cellulose and 0.1mol/L NiCl₂Soaking the mixed solution for 60min, and filtering to obtain a product C;

fourthly, the zipper 7 is unzipped to place the product C into the box body part 6, the zipper 7 is closed, the anode box containing the product C is in sliding connection with the electrochemical corrosion tank 4 through the anode box clamping column 3, 5mol/L hydrochloric acid and 5mol/L absolute ethyl alcohol are added into the electrochemical corrosion tank 4, oxygen is introduced into the vent pipe at the flow rate of 500ml/min, the cathode box and the anode box are respectively and electrically connected with the DPH-20/800 power cabinet through the cathode power line 2 and the anode power line 9, the switch of the DPH-20/800 power cabinet is opened, and 200mA/cm power cabinet is switched on²And (3) carrying out current and electrochemical corrosion for 90min, taking out the anode box through the handle 10, cleaning the anode box by using deionized water, and drying to obtain a porous silicon powder product D, wherein the pore diameter is 500nm-1 mu m, and the porosity is 52%.

The metal salts in the above examples may also be replaced with equimolar amounts of CuCl₂And FeCl₃The inorganic acid salt in the electrochemical corrosion solution can be replaced by sulfuric acid or nitric acid with equimolar amount.

Comparative example 1:

step one, soaking 10g of single crystal silicon powder with the particle diameter of 10 mu m into a mixed solution of 5mol/L hydrofluoric acid and 0.1mol/L silver nitrate for 10min, and then filtering and drying at 100 ℃ to obtain a product A.

And step two, soaking the product A into 5mol/L hydrofluoric acid and 4% hydrogen peroxide by mass for 4h, filtering and drying at 100 ℃ to obtain a finished product B.

Comparative example 2:

step one, soaking 10g of single crystal silicon powder with the particle diameter of 10 mu m into a mixed solution of 5mol/L hydrofluoric acid and 0.2mol/L ferric chloride for 10min, and then filtering and drying at 100 ℃ to obtain a product A.

And step two, soaking the product A into 5mol/L hydrofluoric acid and 4% nitric acid by mass for 6h, filtering and drying at 100 ℃ to obtain a finished product B.

Comparative examples 1 and 2 are described in the actual production methods or in the literature. The preparation processes of comparative examples 1 and 2 require high-difficulty hydrofluoric acid, are harmful to human bodies and environment, and have uncontrollable diameter depth of holes and long preparation period.

Comparative example 3:

in conjunction with the preparation apparatus, the specific preparation steps of this example are as follows

Step one, 30kg of silicon monoxide with the grain diameter of 5 mu m is put into 1mol/L HCl and 2mol/L H₂O₂Soaking the mixed solution for 1h, filtering and then washing by adopting deionized water to obtain a product A;

step two, the product B is put into 0.05mol/L AgNO₃Soaking the mixed solution for 30min, and filtering to obtain a product B;

step three, the zipper 7 is opened to place the product B into the box body part 6, the zipper 7 is closed, the anode box containing the product B is in sliding connection with the electrochemical corrosion tank 4 through the anode box clamping column 3, 0.05mol/L sodium hydroxide and 1mol/L absolute ethyl alcohol are added into the electrochemical corrosion tank 4, oxygen is introduced into the vent pipe at the flow rate of 100ml/min, the cathode and the anode box are respectively and electrically connected with the DPH-20/800 power cabinet through the cathode power line 2 and the anode power line 9, the switch of the DPH-20/800 power cabinet is opened, and 100mA/cm is switched on²And (3) carrying out current and electrochemical corrosion for 20min, taking out the anode box through the handle 10, washing the anode box by using deionized water, and drying to obtain a finished product C which is silicon monoxide with the average diameter of 3 mu m.

In the embodiments 1-5, hydrofluoric acid which is volatile and has irreversible harm to skin, respiratory tract and even bone of a human body is not used, the process has small harm to the human body and the environment, the preparation device and the preparation method are improved, the electrochemical corrosion method is used for preparing the porous silicon powder, the preparation period of the method is short, the pore size and the pore depth can be controlled by changing the current, the electrochemical corrosion time, the metal types in the deposition solution and the components of the electrochemical corrosion solution, the pore distribution of the prepared porous silicon is uniform, the electrochemical corrosion solution of inorganic base and a silicon source react quickly, the method is suitable for preparing the porous silicon with large pore size, and the pore size of the porous silicon can be increased by increasing the current and the electrochemical corrosion time. Wherein comparative example 3 is a control of the examples in the absence of SnCl₂And HCl is used for sensitizing a silicon source, and meanwhile, under the condition that the surfactant is reduced in the deposition solution, metal is difficult to nucleate and grow on the surface of the silicon source, the purpose of depositing the metal is difficult to achieve, differential corrosion cannot be formed on the surface of the silicon source in the electrochemical corrosion process, and therefore porous silicon cannot be prepared.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.