A hierarchical porous silicon nanomaterial and its preparation method and application
Preparation of graded porous silicon nanomaterials by high temperature thermal reduction method solves the problems of complex and high cost in the existing technology, and achieves the improvement of high specific surface area and porosity. It is suitable for electrodes of energy storage devices, showing excellent electrical Chemical properties.
Patent Information
- Application Number
- CN202310325816.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-30
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2043-03-30
AI Technical Summary
The existing preparation methods of graded porous silicon materials have problems such as high raw material costs, complex preparation process, and uneven pore distribution, which cannot achieve industrial production. Moreover, the electronic conductivity of silicon oxide has poor and small specific surface area, which limits its use in the electrodes of energy storage devices. Application.
The high-temperature thermal reduction method is used to prepare the graded porous silicon nanomaterials. The oxide is grown in situ on the surface of silicon oxide, and then calcined and deoxygenated in an inert atmosphere to form a silicon-metal oxide composite nanomaterial and etched in an acid solution. Porous structure, a graded porous silicon nanomaterial with high specific surface area and porosity is obtained.
It realizes the simplicity of the graded porous silicon nanomaterial, low cost and simple process, significantly improves the specific surface area and porosity, and is suitable for electrode materials for energy storage devices, showing excellent electrochemical properties.
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Figure CN116395696B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a regenerative material and a preparation method and application thereof, belonging to the field of structure and design of electrode materials for energy storage devices, and in particular to a hierarchical porous silicon nanomaterial and a preparation method and application thereof. Background Art
[0002] Whether it is clean power generation from renewable energy represented by solar and wind energy, or driving of new energy vehicles dominated by pure electric drive, energy storage devices are indispensable for energy conversion, storage and use. Therefore, people's demand for energy materials and environmental materials is extremely increasing. Energy storage devices mainly include secondary batteries, supercapacitors, etc.
[0003] Hierarchical porous silicon is a porous material composed of micropores, mesopores or macropores. It has unique dielectric properties, optical properties, microelectronic compatibility, large specific surface area and pore controllability, making it widely used in electrode materials for energy storage devices. At present, the main preparation methods of hierarchical porous silicon are wet chemical etching and electrochemical etching. These preparation methods generally have problems such as high raw material cost, complex preparation process, high equipment requirements, and uneven pore distribution, and cannot be industrialized.
[0004] Siloxene is a new type of silicon-based hierarchical material. Three possible planar structural types of siloxene have been proposed in the reported literature: Weiss-type structure, Kautsky-type structure and chain siloxene. In the field of energy storage, siloxene has been proven to be an excellent electrode material for energy storage devices, such as lithium batteries, supercapacitors, and zinc batteries. Compared with other silicon materials, siloxene has the advantages of simple synthesis methods and low cost. However, due to the large number of oxygen-containing functional groups, poor electronic conductivity and small specific surface area, its application in electrodes of energy storage devices is still limited. Summary of the invention
[0005] In order to solve the problems existing in the background technology, the present invention utilizes the high-temperature thermal reducibility of silicon to provide a hierarchical porous silicon nanomaterial and a preparation method and application thereof.
[0006] The technical solution adopted by the present invention is as follows:
[0007] 1. A hierarchical porous silicon nanomaterial:
[0008] The porous silicon nanomaterial has a layered structure in the longitudinal direction, a lateral dimension of the porous silicon nanomaterial of 0.1 to 100 μm, a longitudinal dimension of less than 100 nm, an outer surface of the porous silicon nanomaterial of a uniformly distributed porous structure, and the pores on the outer surface are nearly circular graded pores, and the pore size range of the outer surface pores of the porous silicon nanomaterial is 0.1-300 nm.
[0009] 2. A method for preparing the hierarchical porous silicon nanomaterial comprises the following steps:
[0010] Step 1) preparing siloxane material: slowly adding 1g of calcium silicide CaSi2 into 100-1000mL of hydrochloric acid solution at a temperature of -30-5°C to react for 10-200h, washing the product obtained after the reaction with acetone and water in turn until neutral, filtering and freeze-drying to obtain siloxane;
[0011] Step 2) adding siloxene and the mixed solution into a reactor, in-situ growing oxide on the surface of the siloxene, and then obtaining a siloxene-oxide composite nanomaterial;
[0012] The reactor is a normal pressure reactor or a high pressure reactor. When the reaction is carried out in a high pressure reactor, the reaction pressure is above 0.1 MPa, the reaction temperature is 50-200° C., and the reaction time is greater than 0.5 h.
[0013] Step 3) washing the siloxane-oxide composite nanomaterial obtained in step 2) with alcohol and water in turn, and then placing the washed siloxane-oxide composite nanomaterial in an oven at 50-100° C. for drying;
[0014] Step 4) calcining the dried siloxane-oxide composite nanomaterial under an inert atmosphere, deoxidizing the siloxane after heat treatment to convert it into silicon nanosheets, and reducing the oxide in the siloxane-oxide composite nanomaterial to metal oxide by silicon, thereby obtaining a silicon-metal oxide composite nanomaterial;
[0015] Step 5) placing the silicon-metal oxide composite nanomaterial obtained in step 4) in an acid solution and soaking it for 12-24 hours to obtain a porous silicon nanomaterial;
[0016] Step 6) The porous silicon nanomaterial obtained in step 5) is washed with distilled water until it becomes neutral, and then the washed porous silicon nanomaterial is dried to obtain the final graded porous silicon nanomaterial.
[0017] The concentration of the hydrochloric acid solution in step 1) is 0.05 to 11.8 mol / L, and the freeze-drying temperature is -50 to -30°C.
[0018] The mixed solution in step 2) is mainly composed of metal salts, which are salts of iron, cobalt, copper, manganese, chromium, nickel, silver, titanium, vanadium or zinc. The mixed solution also includes one or more of a precipitant and a regulator, the precipitant is one of ammonium fluoride, urea, phosphate, disodium ethylenediaminetetraacetate, and sodium citrate, and the regulator is one of hydrochloric acid, phosphoric acid, sodium hydroxide, acetic acid, ammonium sulfate, and ammonia.
[0019] The mass ratio of siloxane to oxide in the siloxane-oxide composite nanomaterial is 100:1 to 1:1.
[0020] The oxide in the siloxane-metal oxide composite nanomaterial is one or more of metal oxides, hydroxides and oxyhydroxides.
[0021] The metal oxide is a metal oxide of iron, cobalt, copper, manganese, chromium, nickel, silver, titanium, vanadium or zinc, the hydroxide is a hydroxide of iron, zinc, magnesium, cobalt, aluminum or copper, and the oxyhydroxide is a oxyhydroxide of iron, aluminum, manganese, cobalt, vanadium or chromium.
[0022] The specific steps of step 4) are:
[0023] The dried siloxane-oxide composite nanomaterial is placed in an ark, and calcined at a calcination temperature of 500 to 1500° C. for 0.5 to 10 hours under an inert atmosphere to obtain a silicon-metal oxide composite nanomaterial;
[0024] The mass of the silicon-metal oxide composite nanomaterial is 50-95% of the mass of the siloxane-oxide composite nanomaterial.
[0025] In step 4), the inert atmosphere is nitrogen atmosphere.
[0026] The acid solution in step 5) is one or more of hydrochloric acid, nitric acid, sulfuric acid, perchloric acid, hydroiodic acid, hydrobromic acid, hydrofluoric acid, oxalic acid, boric acid, phosphoric acid and organic carboxylic acid.
[0027] 3. Application of the hierarchical porous silicon nanomaterial prepared by the preparation method:
[0028] The hierarchical porous silicon nanomaterial is used to prepare electrode materials for energy storage devices, and the energy storage devices include lithium batteries, super capacitors and zinc batteries.
[0029] CaSi2 is etched with hydrochloric acid to prepare siloxane, oxide is grown in situ on the surface of siloxane, siloxane-oxide composite nanomaterial is calcined under the protection of inert atmosphere, and post-processed by acid soaking and washing to obtain hierarchical porous silicon nanomaterial. The method of the invention has simple process and low cost. The obtained hierarchical porous silicon nanomaterial has micropores, mesopores and macropores on the surface, high porosity and high specific surface area, and can be used as electrode materials for energy storage devices, such as lithium batteries, supercapacitors, and zinc batteries, and can show excellent electrochemical properties.
[0030] The beneficial effects of the present invention are as follows:
[0031] 1. The hierarchical porous silicon nanomaterial successfully prepared by the present invention is easy to obtain, cost-controlled, simple in process, highly repeatable and highly operable.
[0032] 2. The present invention utilizes the reducibility of silicon in a high temperature environment to reduce the oxides grown on the surface while etching the oxides into the interior of the silicon, which is then immersed in acid to form pores, thus solving the key problem of preparing porous silicon materials that is difficult to achieve with current technology;
[0033] 3. The specific surface area and porosity of the hierarchical porous silicon nanomaterial successfully prepared by the present invention are significantly improved, and it is composed of micropores, mesopores and macropores, and is suitable for use as an electrode material for energy storage devices.
[0034] 4. The present invention can adjust the pore size, porosity, etc. of the graded porous silicon nanomaterial by adjusting the type of oxide, reaction temperature, reaction time, reaction pressure, etc. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Figure 1 is a schematic diagram of the process of preparing the hierarchical porous silicon nanomaterial in Example 1;
[0036] Figure 2 a is the siloxane-oxide composite nanomaterial prepared in Example 1: dense iron oxyhydroxide nanorods are in situ grown on the surface of siloxane by hydrothermal reaction; Figure 2 b is the silicon-metal oxide composite nanomaterial prepared in Example 1: the iron oxyhydroxide nanorods are thermally reduced to ferroferric oxide nanoparticles, which are etched into the surface of siloxane to form a silicon-ferroferric oxide composite nanomaterial;
[0037] Figure 3 a is a surface electron microscope image of siloxane in Example 1, Figure 3 b is the surface electron microscope image of the hierarchical porous silicon nanomaterial prepared in Example 1, Figure 3 c is the surface electron microscope image of the hierarchical porous silicon nanomaterial prepared in Example 2, Figure 3 d is a surface electron microscope image of the hierarchical porous silicon nanomaterial prepared in Example 3;
[0038] Figure 4 a is the N2 adsorption-desorption curve of the hierarchical porous silicon nanomaterial prepared in Example 1, Figure 4 b is a pore size distribution diagram of the hierarchical porous silicon nanomaterial prepared in Example 1;
[0039] Figure 5 This is a long cycle performance diagram of a battery electrode composed of siloxane and hierarchical porous silicon nanomaterials in the sample of Example 1 at a current density of 1000 mA / g;
[0040] Figure 6 a is an electron microscope image of the siloxane battery electrode in the sample prepared in Example 1 after 500 cycles, Figure 6b is an electron microscope image of the graded porous silicon nanomaterial battery electrode in the sample prepared in Example 1 after 500 cycles. DETAILED DESCRIPTION
[0041] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.
[0042] The embodiments of the present invention are as follows, and the method steps are as follows Figure 1 As shown:
[0043] Embodiment 1:
[0044] Step 1), preparing siloxene: slowly add 1g CaSi2 into 100mL of 11.8mol / L hydrochloric acid solution, react at 0°C for 72h, then wash with acetone and deionized water in turn until neutral, and freeze-dry at -30°C to obtain siloxene material;
[0045] Step 2), in situ growing of a metal oxide precursor on the surface of the siloxane raw material by a hydrothermal reaction, and then obtaining a siloxane-oxide composite nanomaterial, such as Figure 2 As shown in a:
[0046] Step 2.1: Prepare the metal oxide precursor solution
[0047] Dissolve ferric chloride hexahydrate (FeCl3.6H2O, 0.2 M) and sodium nitrate (NaNO3, 1.5 M) in distilled water (15 ml) to obtain a metal oxide precursor solution;
[0048] Step 2.2: Then, siloxene (1 g) is dispersed in the metal oxide precursor solution, stirred to obtain a uniformly mixed solution, and the solution is transferred to a stainless steel autoclave lined with polytetrafluoroethylene, heated at 95° C. for 6 hours, and then cooled to room temperature. After the solution is fully reacted, a siloxene-oxide composite nanomaterial is obtained in the stainless steel autoclave, and the siloxene-oxide composite nanomaterial is in powder form;
[0049] The surface electron microscope image of the siloxane raw material is as follows Figure 3 As shown in a.
[0050] Step 3), opening the stainless steel autoclave, washing the siloxane-oxide composite nanomaterial obtained in step 1) with alcohol and water in turn, and then placing the washed siloxane-oxide composite nanomaterial in a 50° C. forced air oven for drying;
[0051] Step 4), heat-treating the dried siloxane-oxide composite nanomaterial to obtain a silicon-metal oxide composite nanomaterial, such as Figure 2 As shown in b:
[0052] The dried siloxane-oxide composite nanomaterial is placed in an ark, and heated to 800°C at a heating rate of 5°C / min in a tube furnace under a nitrogen atmosphere and kept at this temperature for 1 hour, and then naturally cooled to room temperature to obtain a silicon-metal oxide composite nanomaterial;
[0053] Step 5), placing the silicon-metal oxide composite nanomaterial obtained in step 3) in hydrochloric acid for 12 hours to remove the reduced metal oxide, and then obtaining a porous silicon nanomaterial;
[0054] Step 6), the porous silicon nanomaterial obtained in step 4) is washed with distilled water until it is neutral, and then the washed porous silicon nanomaterial is dried to obtain the final graded porous silicon nanomaterial, such as Figure 3 As shown in b.
[0055] The hierarchical porous structure of hierarchical porous silicon nanomaterials was characterized by nitrogen adsorption-desorption. Figure 4 As shown in a, the adsorption-desorption isotherm of the hierarchical porous silicon nanomaterial is a type IV curve, and there is a very obvious hysteresis loop, indicating that the hierarchical porous silicon nanomaterial has a large number of micropores, mesopores and macropores, which is also Figure 4 b pore size distribution diagram, and the specific surface area of the graded porous silicon nanomaterial is as high as 257.5 m 2 / g, which is much higher than the specific surface area of 67.5m 2 / g.
[0056] The hierarchical porous silicon nanomaterials are used to prepare the negative electrode of lithium batteries: Siloxane and hierarchical porous silicon nanomaterials, conductive carbon black, and sodium alginate binder are used in a ratio of 6:2:2 to prepare an electrode slurry, which is coated on copper foil and dried to obtain an electrode plate. A lithium plate is used as the counter electrode, Ceglard2400 (PP) is used as the separator, LIR-2032 is used as the battery shell, and 1M lithium hexafluorophosphate (LiPF6), a mixed solution of ethylene carbonate / diethyl carbonate (EC / DEC=1:1, v / v) containing 5wt% of fluoroethylene carbonate (FEC) is used as the electrolyte to prepare a half-cell to test the electrode performance. Figure 5 It can be seen that the battery cycle stability of hierarchical porous silicon nanomaterials is much higher than that of siloxane. Figure 6 a shows an electron microscope image of the siloxane raw material electrode after 500 cycles of battery cycling. There are obvious cracks on the surface. Figure 6 b shows an electron microscope image of a graded porous silicon nanomaterial electrode that has been cycled 500 times. Due to its abundant pores, it has reserved space for expansion, so there are very few cracks.
[0057] Embodiment 2:
[0058] Step 1) Preparation of siloxane: Slowly add 1 g of CaSi2 into 100 mL of 5 mol / L hydrochloric acid solution, react at 0°C for 96 h, then wash with acetone and deionized water in turn until neutral, and freeze-dry at -40°C to obtain siloxane.
[0059] Step 2), a metal oxide precursor is grown in situ on the surface of siloxene by a hydrothermal reaction, and then a siloxene-oxide composite nanomaterial is obtained:
[0060] Step 1.1: Prepare the metal oxide precursor solution
[0061] Cobalt nitrate hexahydrate (Co(NO3)6.6H2O, 6 mM), ammonium fluoride (NH4F, 12 mM), and urea (Co(NH2)2), 30 mM) were dissolved in distilled water (35 ml) to obtain a metal oxide precursor solution;
[0062] Step 1.2: Then, siloxene (1 g) is dispersed in the metal oxide precursor solution, and the solution is continuously stirred and ultrasonically treated for 15 min to obtain a uniformly mixed solution. The solution is transferred to a stainless steel autoclave lined with polytetrafluoroethylene, heated at 120° C. for 6 h, and then cooled to room temperature. After the solution is fully reacted, a siloxene-oxide composite nanomaterial is obtained in the stainless steel autoclave;
[0063] Step 3), opening the stainless steel autoclave, washing the siloxane-oxide composite nanomaterial obtained in step 1) with alcohol and water in turn, and then placing the washed siloxane-oxide composite nanomaterial in a 50° C. forced air oven for drying;
[0064] Step 4), heat-treating the dried siloxane-oxide composite nanomaterial to obtain a silicon-metal oxide composite nanomaterial:
[0065] The dried siloxane-oxide composite nanomaterial was placed in an ark, and heated to 900°C at a heating rate of 5°C / min in a tube furnace under a nitrogen atmosphere and kept warm for 2 hours, and then naturally cooled to room temperature to obtain a silicon-metal oxide composite nanomaterial.
[0066] Step 5), placing the silicon-metal oxide composite nanomaterial obtained in step 4) in hydrochloric acid for 12 hours to remove the reduced metal oxide, and then obtaining a porous silicon nanomaterial;
[0067] Step 6), the porous silicon nanomaterial obtained in step 5) is washed with distilled water until it is neutral, and then the washed porous silicon nanomaterial is dried to obtain the final graded porous silicon nanomaterial, such as Figure 3 As shown in c.
[0068] Embodiment 3:
[0069] Step 1) Preparation of siloxane: Slowly add 1 g of CaSi2 into 100 mL of 5 mol / L hydrochloric acid solution, react at 0°C for 96 h, then wash with acetone and deionized water in turn until neutral, and freeze-dry at -40°C to obtain siloxane.
[0070] Step 2), firstly, a metal oxide precursor is in situ grown on the surface of the siloxane raw material by a hydrothermal reaction, and then a siloxane-oxide composite nanomaterial is obtained:
[0071] Step 1.1: Prepare the metal oxide precursor solution
[0072] Zinc nitrate hexahydrate (Zn(NO3)2.6H2O, 0.014 M) and sodium hydroxide (NaOH, 0.042 M) were dissolved in distilled water (30 ml) to obtain a metal oxide precursor solution;
[0073] Step 1.2: Then, siloxene (1 g) was dispersed in the metal oxide precursor solution, and the solution was continuously stirred and ultrasonically treated for 15 min to obtain a uniformly mixed solution. The solution was transferred to a stainless steel autoclave lined with polytetrafluoroethylene, and then heated at 130° C. for 10 hours and cooled to room temperature. After the solution was fully reacted, a siloxene-oxide composite nanomaterial was obtained in the stainless steel autoclave;
[0074] Step 3), opening the stainless steel autoclave, washing the siloxane-oxide composite nanomaterial obtained in step 1) with alcohol and water in turn, and then placing the washed siloxane-oxide composite nanomaterial in a 50° C. forced air oven for drying;
[0075] Step 4), heat-treating the dried siloxane-oxide composite nanomaterial to obtain a silicon-metal oxide composite nanomaterial:
[0076] The dried siloxane-oxide composite nanomaterial was placed in an ark, and heated to 700°C at a heating rate of 5°C / min in a tube furnace under a nitrogen atmosphere and kept warm for 1 hour, and then naturally cooled to room temperature to obtain a silicon-metal oxide composite nanomaterial.
[0077] Step 5), placing the silicon-metal oxide composite nanomaterial obtained in step 3) in hydrochloric acid for 12 hours to remove the reduced metal oxide, and then obtaining a hierarchical porous silicon nanomaterial;
[0078] Step 6), washing the graded porous silicon nanomaterial obtained in step 4) with distilled water until it is neutral, and then drying the washed graded porous silicon nanomaterial to obtain the final graded porous silicon nanomaterial, such as Figure 3 As shown in d.
Claims
1. A method for preparing hierarchical porous silicon nanomaterials, It is characterized in that The following steps are involved: Step 1) Preparation of siloxane material: 1g of calcium silicide CaSi 2 Add 100-1000 mL of hydrochloric acid solution to react for 10-200 hours, wash the product obtained after the reaction with acetone and water in sequence until neutral, filter and freeze-dry to obtain siloxane; Step 2) adding siloxene and the mixed solution into a reactor, in-situ growing oxide on the surface of siloxene, and then obtaining siloxene-oxide composite nanomaterials; The mass ratio of siloxane to oxide in the siloxane-oxide composite nanomaterial is 100:1 to 1:1; The mixed solution in step 2) includes a metal salt, and the metal salt is a salt of iron, cobalt, copper, manganese, chromium, nickel, silver, titanium, vanadium or zinc; Step 3) washing the siloxane-oxide composite nanomaterial obtained in step 2) with alcohol and water in turn, and then placing the washed siloxane-oxide composite nanomaterial in an oven at 50-100° C. for drying; Step 4) calcining the dried siloxane-oxide composite nanomaterial under an inert atmosphere to obtain a silicon-metal oxide composite nanomaterial; The mass of the silicon-metal oxide composite nanomaterial is 50-95% of the mass of the siloxane-oxide composite nanomaterial; Step 5) Soaking the silicon-metal oxide composite nanomaterial obtained in step 4) in an acid solution for 12-24 hours to obtain a porous silicon nanomaterial; Step 6) The porous silicon nanomaterial obtained in step 5) is washed with distilled water until it becomes neutral, and then the washed porous silicon nanomaterial is dried to obtain the final graded porous silicon nanomaterial.
2. The method for preparing a hierarchical porous silicon nanomaterial according to claim 1, Features: The concentration of the hydrochloric acid solution in step 1) is 0.05-11.8 mol / L, and the freeze-drying temperature is -50--30°C.
3. The method for preparing a hierarchical porous silicon nanomaterial according to claim 1, Features: The mixed solution in step 2) further comprises one or more of a precipitant and a regulator, wherein the precipitant is one of ammonium fluoride, urea, phosphate, disodium ethylenediaminetetraacetate, and sodium citrate, and the regulator is one of hydrochloric acid, phosphoric acid, sodium hydroxide, acetic acid, ammonium sulfate, and ammonia water.
4. The method for preparing a hierarchical porous silicon nanomaterial according to claim 1, Features: The oxide in the siloxane-oxide composite nanomaterial is one or more of metal oxides, hydroxides and oxyhydroxides.
5. The method for preparing a hierarchical porous silicon nanomaterial according to claim 1, Features: The specific steps of step 4) are: The dried siloxane-oxide composite nanomaterial is placed in an ark, and calcined at a calcination temperature of 500-1500° C. for 0.5-10 hours under an inert atmosphere to obtain a silicon-metal oxide composite nanomaterial.
6. The method for preparing a hierarchical porous silicon nanomaterial according to claim 1, Features: The inert atmosphere in step 4) is nitrogen atmosphere.
7. The method for preparing a hierarchical porous silicon nanomaterial according to claim 1, Features: The acid solution in step 5) is one or more of hydrochloric acid, nitric acid, sulfuric acid, perchloric acid, hydroiodic acid, hydrobromic acid, hydrofluoric acid, oxalic acid, boric acid, phosphoric acid and organic carboxylic acid.
8. Application of the hierarchical porous silicon nanomaterial prepared by the preparation method according to any one of claims 1 to 7, Features: The hierarchical porous silicon nanomaterial is used to prepare electrode materials for energy storage devices, and the energy storage devices include lithium batteries, super capacitors and zinc batteries.
9. A hierarchical porous silicon nanomaterial, Features: The hierarchical porous silicon nanomaterial is prepared by the preparation method as described in any one of claims 1-7; the porous silicon nanomaterial has a layered structure in the longitudinal direction, the lateral size of the porous silicon nanomaterial is 0.1~100μm, the longitudinal size is less than 100nm, the outer surface of the porous silicon nanomaterial is a uniformly distributed porous structure, and the pore size range of the surface pores of the porous silicon nanomaterial is 0.1-300nm.