A preparation method of three-dimensional copper cage porous silicon oxide material

Abstract

The present invention discloses a method for preparing a three-dimensional copper cage porous silicon oxide material, belonging to the field of preparation and application of inorganic composite materials. The method comprises mixing a silicon material with a copper salt, heating the mixture to 600-800°C under inert or vacuum conditions for a reaction of 0.5-2h to obtain silicon particles containing a copper silicide structure, then adding the product to 1-13M ammonia water and mixing evenly. The mixture is reacted at 90-110°C for 0.5-3 days, causing the copper silicide to decompose and form a porous structure. Ammonium ions react with copper precipitated on the particle surface, and spiny copper oxide nanocrystals grow on the surface of the porous silicon material. The mixture is then stirred and reduced by adding a reducing agent, or the product is reduced at high temperature under reducing gas conditions such as hydrogen to obtain a Si / Cu nanocomposite material with a cage-like encapsulated structure. This method overcomes the problems of silicon material expansion and cracking and poor conductivity during the electrochemical reaction of lithium batteries, as well as the shortcomings of current silicon composite materials such as high synthesis cost and low yield.

Description

Technical Field

[0001] The present invention relates to the preparation and application of inorganic composite materials, specifically a method for preparing a three-dimensional copper cage porous silica material. This material can be used as an active substance in lithium battery negative electrodes to increase the energy storage density of electrochemical devices, or as a catalyst in catalytic reactions to increase the yield of catalytic products. Background Art

[0002] With the development of the global economy, the demand for energy is increasing. However, with the deterioration of the ecological environment and the increasing problem of global warming caused by the combustion of fossil fuels, the greenhouse effect caused by carbon dioxide emissions from fossil fuel combustion is placing tremendous pressure on our environment. Global energy transformation is imminent. Efficiently converting the chemical energy of fuels into electrical energy and developing new technologies for electrical energy storage and conversion, ultimately replacing the highly polluting and energy-inefficient use of fossil fuels in daily life with electricity, has become a hot topic. Lithium-ion batteries, as a new type of energy storage device, are currently the most important electrochemical energy storage method. Their widespread use can significantly reduce carbon emissions. In the current development of high-energy-density lithium-ion batteries, with the breakthrough of new ternary cathode materials, the potential of widely commercialized graphite anode materials has been fully developed. Graphite anodes have a theoretical capacity of ~372 mA h / g. Compared to graphite, silicon anodes have a higher theoretical specific capacity (>4000 mA h / g) and a suitable discharge voltage (~0.3 V vs. Li / Li). + ) and similar raw material costs, silicon holds great promise as a next-generation lithium battery anode material. Therefore, our research focuses on finding new silicon-containing materials for efficient lithium-ion battery anodes. We react copper salts with bare silicon to form a new Cu / Si nanocomposite material. This material combines the buffering structure of porous silicon with the excellent conductivity of metallic copper. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides a method for preparing a three-dimensional copper cage porous silicon oxide material, which is a new method for obtaining a Cu / Si composite material.

[0004] The method can be briefly described as follows: Silicon material (nanosilicon or micron-sized silicon particles) is mixed with a copper salt (CuCl, CuCl2) (mass ratio of 10:1 to 1:2) to react and produce silicon particles containing a copper silicide structure. The mixture is then heated to 600-800°C under inert or vacuum conditions for 0.5-2 hours to produce silicon particles containing a copper silicide structure. The resulting mixture is then added to 1-13M aqueous ammonia, ultrasonically mixed, and reacted at 90-110°C for 0.5-3 days to promote the decomposition of the copper silicide, thereby forming a porous structure within the particles. Spike-like copper oxide nanocrystals grow on the surface of the porous silicon material through the reaction between ammonium ions and copper precipitated on the particle surface. Finally, the product is reduced by adding a reducing agent (NaBH4, hydrazine hydrate) with stirring, or by heating to 300-500°C under a reducing gas such as hydrogen to produce the final composite active material. This results in a Si / Cu nanocomposite material with a cage-like structure encapsulating the silicon and copper materials.

[0005] Compared with the existing technology, the present invention overcomes the problems of expansion and cracking and poor conductivity of silicon materials during electrochemical reactions, as well as the shortcomings of current silicon composite materials such as high synthesis cost and low yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present invention is further described in detail below with reference to the accompanying drawings and specific application modes:

[0007] Figure 1 This is a transmission electron microscope image of silicon nanoparticles containing copper silicide obtained after sintering.

[0008] Figure 2 It is a transmission electron microscope and element distribution map of Si / Cu nanocomposite material with a cage-like encapsulation structure obtained after the reaction of silicon and copper materials.

[0009] Figure 3 This is the first cycle charge and discharge curve of a lithium-ion battery cell using Si / Cu nanocomposite materials as active materials. DETAILED DESCRIPTION

[0010] The present invention is illustrated below using specific examples. It should be noted that the examples are intended only to further illustrate the present invention and are not to be construed as limiting the scope of the present invention. The present invention is not limited thereto in any way. Those skilled in the art may make non-essential improvements and adjustments based on the above-described invention.

[0011] Example 1

[0012] 1. Silicon material (micron-sized silicon particles) is mixed with copper salt (CuCl) (mass ratio 1:2), and then heated to 800°C under inert or vacuum conditions for 1 hour to obtain silicon particles containing copper silicide structure.

[0013] 2. The product was then added to 13M ammonia water, ultrasonically mixed, and reacted at 110°C for 3 days to obtain a composite material with copper oxide nanostructures on the surface.

[0014] 3. The product is then reduced by adding a reducing agent (NaBH4, hydrazine hydrate) and stirring, or the product is heated to 300°C under hydrogen conditions to obtain the final composite material active material.

[0015] 4. Electrochemical energy storage exploration of the product: After mixing the active material, acetylene black, and PVDF in a ratio of 6:3:1, the total mass of the material is 100 mg. About 0.7 ml of NMP is added and stirred into a paste. The sample is scraped onto copper foil and coated. After the coating is dry, the electrode is cut out using a microtome. In an Ar gas atmosphere glove box, the active material electrode is used as the positive electrode and the lithium sheet is used as the negative electrode. A half-cell is assembled and performance tested. (Performance see Figure 3 )

[0016] Example 2

[0017] 1. Silicon material (nano-silicon) and copper salt (CuCl) are mixed (mass ratio 1:2), and then heated to 800°C under inert or vacuum conditions for 1 hour to obtain silicon particles containing copper silicide structure.

[0018] 2. The product was then added to 13M ammonia water, ultrasonically mixed, and reacted at 110°C for 3 days to obtain a composite material with copper oxide nanostructures on the surface.

[0019] 3. The product is then reduced by adding a reducing agent (NaBH4, hydrazine hydrate) and stirring, or the product is heated to 300°C under hydrogen conditions to obtain the final composite material active material.

[0020] 4. Exploring the electrochemical energy storage of the product: After mixing the active material, acetylene black, and PVDF in a ratio of 6:3:1, for a total mass of 100 mg, add approximately 0.7 ml of NMP and stir until a paste forms. The sample is then scraped onto copper foil and coated. After the coating dries, electrodes are cut using a microtome. In an Ar atmosphere glove box, a half-cell is assembled, using the active material electrode as the positive electrode and the lithium sheet as the negative electrode, for performance testing.

[0021] Example 3

[0022] 1. Silicon material (micron-sized silicon particles) is mixed with copper salt (CuCl2) (mass ratio 1:2), and then heated to 800°C under inert or vacuum conditions for 1 hour to obtain silicon particles containing copper silicide structure.

[0023] 2. The product was then added to 13M ammonia water, ultrasonically mixed, and reacted at 95°C for 3 days to obtain a composite material with copper oxide nanostructures on the surface.

[0024] 3. The product is then reduced by adding a reducing agent (NaBH4, hydrazine hydrate) and stirring, or the product is heated to 300°C under hydrogen conditions to obtain the final composite material active material.

[0025] 4. Exploring the electrochemical energy storage of the product: After mixing the active material, acetylene black, and PVDF in a ratio of 6:3:1, for a total mass of 100 mg, add approximately 0.7 ml of NMP and stir until a paste forms. The sample is then scraped onto copper foil and coated. After the coating dries, electrodes are cut using a microtome. In an Ar atmosphere glove box, a half-cell is assembled, using the active material electrode as the positive electrode and the lithium sheet as the negative electrode, for performance testing.

[0026] Example 4

[0027] 1. Silicon material (nanoscale silicon particles) is mixed with copper salt (CuCl2) (mass ratio 1:2), and then heated to 800°C under inert or vacuum conditions for 1 hour to obtain silicon particles containing copper silicide structure.

[0028] 2. The product was then added to 13M ammonia water, ultrasonically mixed, and reacted at 95°C for 3 days to obtain a composite material with copper oxide nanostructures on the surface.

[0029] 3. The product is then reduced by adding a reducing agent (NaBH4, hydrazine hydrate) and stirring, or the product is heated to 300°C under hydrogen conditions to obtain the final composite material active material.

[0030] 4. Exploring the electrochemical energy storage of the product: After mixing the active material, acetylene black, and PVDF in a ratio of 6:3:1, for a total mass of 100 mg, add approximately 0.7 ml of NMP and stir until a paste forms. The sample is then scraped onto copper foil and coated. After the coating dries, electrodes are cut using a microtome. In an Ar atmosphere glove box, a half-cell is assembled, using the active material electrode as the positive electrode and the lithium sheet as the negative electrode, for performance testing.

[0031] Example 5

[0032] 1. Silicon material (micron-sized silicon particles) is mixed with copper salt (CuCl) (mass ratio 10:1), and then heated to 800°C under inert or vacuum conditions for 1 hour to obtain silicon particles containing copper silicide structure.

[0033] 2. The product was then added to 13M ammonia water, ultrasonically mixed, and reacted at 95°C for 3 days to obtain a composite material with copper oxide nanostructures on the surface.

[0034] 3. The product is then reduced by adding a reducing agent (NaBH4, hydrazine hydrate) and stirring, or the product is heated to 300°C under hydrogen conditions to obtain the final composite material active material.

[0035] 4. Exploring the electrochemical energy storage of the product: After mixing the active material, acetylene black, and PVDF in a ratio of 6:3:1, for a total mass of 100 mg, add approximately 0.7 ml of NMP and stir until a paste forms. The sample is then scraped onto copper foil and coated. After the coating dries, electrodes are cut using a microtome. In an Ar atmosphere glove box, a half-cell is assembled, using the active material electrode as the positive electrode and the lithium sheet as the negative electrode, for performance testing.

[0036] Example 6

[0037] 1. Silicon material (nano-silicon-grade silicon particles) is mixed with copper salt (CuCl) (mass ratio 10:1), and then heated to 800°C under inert or vacuum conditions for 1 hour to obtain silicon particles containing copper silicide structure.

[0038] 2. The product was then added to 13M ammonia water, ultrasonically mixed, and reacted at 95°C for 3 days to obtain a composite material with copper oxide nanostructures on the surface.

[0039] 3. The product is then reduced by adding a reducing agent (NaBH4, hydrazine hydrate) and stirring, or the product is heated to 300°C under hydrogen conditions to obtain the final composite material active material.

[0040] 4. Exploring the electrochemical energy storage of the product: After mixing the active material, acetylene black, and PVDF in a ratio of 6:3:1, for a total mass of 100 mg, add approximately 0.7 ml of NMP and stir until a paste forms. The sample is then scraped onto copper foil and coated. After the coating dries, electrodes are cut using a microtome. In an Ar atmosphere glove box, a half-cell is assembled, using the active material electrode as the positive electrode and the lithium sheet as the negative electrode, for performance testing.

[0041] like Figure 1 As shown, the silicon nanoparticles containing copper silicide obtained after sintering clearly have a core-shell structure

[0042] like Figure 2 As shown in the figure, the transmission electron microscope (TEM) image of the composite material obtained after the reaction of silicon and copper materials shows that the Si / Cu nanocomposite material has a cage-like structure. The element distribution map proves that the elements that constitute the cage on the outside of the material are mainly Cu, and Si and O elements are distributed inside the structure.

[0043] like Figure 3As shown, the lithium-ion battery plate battery using the Si / Cu nanocomposite material synthesized in Example 1 as the active material has a discharge capacity of 1510.5 mA h / g and a charge capacity of 1088.4 mA h / g.

Claims

1. A method for preparing a three-dimensional copper cage porous silicon oxide material, characterized in that: The following steps are involved: (1) Mixing silicon material and copper salt in a mass ratio of 10:1 to 1:2; (2) heating to 600-800° C. under inert or vacuum conditions for 0.5-2 hours to obtain silicon particles containing a copper silicide structure; (3) adding the product to 1-13M ammonia water, mixing well, and reacting at 90-110°C for 0.5-3 days to decompose the copper silicide and form a porous structure. At the same time, the reaction between ammonium ions and copper precipitated on the particle surface grows on the surface of the porous silicon material to form thorn-like copper oxide nanocrystals; (4) The product is then reduced by adding a reducing agent and stirring, or the product is heated to 300-500° C. under reducing gas conditions to obtain a Si / Cu nanocomposite material with a cage-like encapsulation structure of silicon and copper materials.

2. The method for preparing the three-dimensional copper cage porous silicon oxide material according to claim 1, characterized in that: The silicon material is nanometer or micrometer-sized silicon particles.

3. The method for preparing the three-dimensional copper cage porous silicon oxide material according to claim 1, characterized in that: The copper salt is CuCl or CuCl2.

4. The method for preparing the three-dimensional copper cage porous silicon oxide material according to claim 1, characterized in that: The reducing gas in step (4) is hydrogen or alcohol steam.

5. The method for preparing the three-dimensional copper cage porous silicon oxide material according to claim 1, characterized in that: The reducing agent is NaBH4 or hydrazine hydrate.

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