阅读说明：本技术 一种基于叶蜡石制备的硅/铝氧化物纳米复合材料及其方法 (Silicon/aluminum oxide nano composite material prepared based on pyrophyllite and method thereof ) 是由 陈情泽 朱润良 韦寿淑 杜静 何宏平 朱建喜 于 2021-09-17 设计创作，主要内容包括：本申请涉及材料领域,具体而言,涉及一种基于叶蜡石制备的硅/铝氧化物纳米复合材料及其方法。方法包括：将含有叶蜡石、金属料的混合物在惰性气氛中球磨,使叶蜡石被金属料还原；其中,金属料包括金属铝。该方法制备得到的硅/铝氧化物纳米复合材料包含单质硅和铝氧化物,呈现类层状多孔结构,具有良好的界面稳定性、较大的振实密度、快速的离子/电子传输性能,可用作电池负极材料。(The application relates to the field of materials, in particular to a silicon/aluminum oxide nano composite material prepared based on pyrophyllite and a method thereof. The method comprises the following steps: ball-milling a mixture containing pyrophyllite and a metal material in an inert atmosphere to reduce the pyrophyllite by the metal material; wherein the metal material comprises metal aluminum. The silicon/aluminum oxide nano composite material prepared by the method contains simple substance silicon and aluminum oxide, presents a layered porous structure, has good interface stability, larger tap density and fast ion/electron transmission performance, and can be used as a battery cathode material.)

1. A method for preparing a silicon/aluminum oxide nanocomposite material based on pyrophyllite is characterized by comprising the following steps:

ball-milling a mixture containing pyrophyllite and a metal material in an inert atmosphere to reduce the pyrophyllite by the metal material;

wherein the metal material comprises metallic aluminum.

2. The method for preparing a silicon/aluminum oxide nanocomposite material based on pyrophyllite according to claim 1,

the ball milling device also comprises: and preserving the heat of the ball-milled materials for more than 0.5h at 500-900 ℃ in an inert atmosphere.

3. The method for preparing a silicon/aluminum oxide nanocomposite material based on pyrophyllite according to claim 1,

the mass ratio of the pyrophyllite to the metal material is 1 (0.3-3);

optionally, the metal material is powder with a particle size of less than 2 mm;

optionally, the metal material further comprises at least one of metal zinc, metal tin, metal copper, metal nickel, metal iron and metal manganese.

4. The method for preparing a silicon/aluminum oxide nanocomposite material based on pyrophyllite according to claim 1,

the mixture further comprises an inorganic salt;

optionally, the inorganic salt comprises NaCl, KCl, LiCl, ZnCl₂、CaCl₂、MgCl₂And AlCl₃At least one of;

optionally, the mass ratio of the pyrophyllite to the inorganic salt is 1 (0.1-3).

5. The method for preparing a silicon/aluminum oxide nanocomposite material based on pyrophyllite according to claim 1,

the mixture is subjected to ball milling in an inert atmosphere; the mass ratio of the grinding balls to the mixture is (10-50): 1;

optionally, the material of the grinding balls is any one of corundum, zirconia, cemented carbide, stainless steel, agate and silicon nitride.

6. A silicon/aluminum oxide nanocomposite material, characterized in that it is obtained by the method for preparing a silicon/aluminum oxide nanocomposite material based on pyrophyllite according to any one of claims 1 to 5.

7. A method for preparing a porous silicon/aluminum oxide nanocomposite material based on pyrophyllite is characterized by comprising the following steps: the silicon/aluminum oxide nanocomposite material according to claim 6 is reacted with an acid solution, washed with water and dried.

8. The method for preparing a porous silicon/aluminum oxide nanocomposite material based on pyrophyllite according to claim 7,

the acid solution comprises at least one of hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid;

optionally, the mass concentration of the acid solution is 1-25%.

9. A porous silicon/aluminum oxide nanocomposite material, characterized in that it is obtained by the method for preparing a porous silicon/aluminum oxide nanocomposite material based on pyrophyllite according to claim 7 or 8.

10. A secondary battery anode, characterized in that it comprises the silicon/aluminum oxide nanocomposite material according to claim 6;

alternatively, the secondary battery anode comprises the porous silicon/aluminum oxide nanocomposite of claim 9.

Technical Field

The application relates to the field of mineral utilization, in particular to a silicon/aluminum oxide nano composite material prepared based on pyrophyllite and a method thereof.

Background

Pyrophyllite is a 2:1 type hydrous aluminosilicate mineral with a natural layered structure, is usually produced in aluminous rocks, and is mainly prepared from medium-acid volcanic rocks or volcanic tuff through low-grade modification and alteration. Pyrophyllite has the molecular formula of Al₂Si₄O₁₀(OH)₂Or Al₂O₃·4SiO₂·H₂O, theoretical chemical composition 28.3% Al₂O₃、66.7％SiO₂And 5.0% H₂O; the pyrophyllite hardly has structural charges, interlayer domains do not contain cations and water molecules, the bonding force between structural unit layers is weak, and the pyrophyllite easily slides along a (001) plane under the action of shearing force. Pyrophyllite is usually produced in the form of an aggregate of compact blocks, tablets or radial shapes, and has soft and fine texture. The pyrophyllite has the characteristics of no toxicity, high temperature resistance, corrosion resistance, low thermal expansion coefficient, good insulativity, good pressure transmission performance and sealing performance, no expansibility and plasticity in water and the like, and is widely applied to the fields of building materials, metallurgy, light industry, chemical industry, national defense and the like. However, the overall level of application of pyrophyllite is relatively low and high value utilization of new technologies is lacking. Therefore, it is urgently needed to develop a high-value utilization method of pyrophyllite, widen the application field of pyrophyllite and improve the added value of products.

The application is proposed in order to broaden the application field of pyrophyllite.

Disclosure of Invention

An object of the embodiments of the present application is to provide a silicon/aluminum oxide nanocomposite prepared based on pyrophyllite and a method thereof.

In a first aspect, the present application provides a method for preparing a silicon/aluminum oxide nanocomposite material based on pyrophyllite, comprising:

ball-milling a mixture containing pyrophyllite and a metal material in an inert atmosphere to reduce the pyrophyllite by the metal material; wherein the metal material comprises metallic aluminum.

The pyrophyllite is rich in resources, and the cost is low due to the fact that the pyrophyllite is used as a raw material; the ball milling is adopted to initiate the reaction of the reducing metal aluminum and the exposed silicon-oxygen tetrahedron, the method can omit heating procedure and equipment without heating, and in addition, the metal material and the pyrophyllite which are both solid phases are fully contacted in the ball milling process, so that the reaction is more thorough; the preparation method is simple, the used equipment is low in cost, the process conditions are not harsh, and a foundation is provided for large-scale preparation.

The silicon/aluminum oxide nano composite material prepared by the method has a layered porous structure, has good interface stability, higher tap density and fast ion/electron transmission performance, and can be used as a secondary battery cathode material.

In some embodiments of the first aspect of the present application, the ball milling further comprises: and preserving the heat of the ball-milled materials for more than 0.5h at 500-900 ℃ in an inert atmosphere.

In some embodiments of the first aspect of the present application, the mass ratio of the pyrophyllite to the metal material is 1 (0.3-3);

optionally, the metal material is powder with a particle size of less than 2 mm;

optionally, the metal material further comprises at least one of metal zinc, metal tin, metal copper, metal nickel, metal iron and metal manganese.

In some embodiments of the first aspect of the present application, the mixture further comprises an inorganic salt;

optionally, the inorganic salt comprises NaCl, KCl, LiCl, ZnCl₂、CaCl₂、MgCl₂And AlCl₃At least one of;

optionally, the mass ratio of the pyrophyllite to the inorganic salt is 1 (0.1-3).

In some embodiments of the first aspect of the present application, the mixture is in a ball milling process under an inert atmosphere; the mass ratio of the grinding balls to the mixture is (10-50): 1;

optionally, the material of the grinding balls is any one of corundum, zirconia, cemented carbide, stainless steel, agate and silicon nitride.

In a second aspect, the present application provides a silicon/aluminum oxide nanocomposite material prepared by the above method for preparing a silicon/aluminum oxide nanocomposite material based on pyrophyllite.

In a third aspect, the present application provides a method for preparing a porous silicon/aluminum oxide nanocomposite material based on pyrophyllite, comprising: the silicon/aluminum oxide nano composite material is adopted to react with acid solution, and then the silicon/aluminum oxide nano composite material is washed by water and dried.

In some embodiments, the acid solution comprises at least one of hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid;

optionally, the mass concentration of the acid solution is 1-25%;

optionally, the reaction time with the acid solution is 0.1-12 h.

In a fourth aspect, the present application provides a porous silicon/aluminum oxide nanocomposite material prepared by the above method for preparing a porous silicon/aluminum oxide nanocomposite material based on pyrophyllite.

A fifth aspect of the present application provides a secondary battery anode comprising the above silicon/aluminum oxide nanocomposite;

alternatively, the secondary battery anode comprises the porous silicon/aluminum oxide nanocomposite material.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

FIG. 1 shows an X-ray diffraction pattern of a porous silicon/aluminum oxide nanocomposite provided in example 1;

FIG. 2 shows a Si 2p high resolution X-ray photoelectron spectrum of the porous silicon/aluminum oxide nanocomposite provided in example 1;

FIG. 3 shows the Al2p high resolution X-ray photoelectron spectrum of the porous silicon/aluminum oxide nanocomposite provided in example 1;

FIG. 4 shows a scanning electron microscope image of the porous silicon/aluminum oxide nanocomposite provided in example 1.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The following is a detailed description of the pyrophyllite-based silicon/aluminum oxide nanocomposite material prepared according to the examples of the present application and the method thereof.

A method for preparing a silicon/aluminum oxide nanocomposite material based on pyrophyllite, comprising:

ball-milling a mixture containing pyrophyllite and a metal material in an inert atmosphere to reduce the pyrophyllite by the metal material;

wherein the metal material comprises metal aluminum.

Ball milling the mixture containing pyrophyllite and metal material in inert atmosphere.

In the present application, "silicon/aluminum oxide" means that the material contains silicon simple substance and aluminum oxide; it should be noted that the silicon/aluminum oxide nanocomposite may contain not only the simple substance silicon and aluminum oxide but also metal aluminum and the like that have not completely reacted.

Illustratively, the time of ball milling may be 0.5h or more; the ball milling time is 0.5-72 h. For example, the ball milling time can be 0.5h, 0.6h, 1h, 2h, 3h, 4h, 5h, 6h, 10h, 13h, 20h, 50h, 60h, 72h, and the like.

The basic structural unit of pyrophyllite is composed of two silica tetrahedral sheets and an aluminum octahedral sheet sandwiched between the two silica tetrahedral sheets, and two elements of silicon and aluminum exist in the forms of the silica tetrahedral sheet and the aluminum octahedral sheet respectively, so that the pyrophyllite is an ideal silicon source and aluminum source; the pyrophyllite interlayer does not contain water molecules and cations, the layer charge is zero, the structural unit interlayer is combined by weak van der Waals force, the sheet layer is easily opened by mechanical action, the silica tetrahedral sheet is exposed, and the reduction reaction is promoted to occur; the octahedral sheet layer can be used as template and barrier layer to induce the product to form layer-like structure. On one hand, mechanical energy is converted into heat energy by ball milling, and the heat energy is accumulated to a certain degree, so that the reaction of the reducing metal aluminum powder and the exposed silicon-oxygen tetrahedron is initiated; on the other hand, the pyrophyllite layer can be stripped by ball milling, the size of reactants is reduced, and the system reaction is more uniform; and under the ball milling effect, the tap density of the material can be increased. The product obtained by the reaction contains aluminum oxide and simple substance silicon, the aluminum oxide can be directly used as a protective layer of the simple substance silicon and is not required to be removed by acid cleaning, the preparation process is greatly simplified, and the cost is saved; porous silicon/aluminum oxide nanocomposites can also be prepared by further acid treatment.

Based on the above properties, the silicon/aluminum oxide nanocomposite can be used to prepare a negative electrode for a secondary battery, for example, a negative electrode for a lithium battery.

In some embodiments of the present application, the mass ratio of the pyrophyllite to the metal material is 1 (0.3-3), for example, the mass ratio of the pyrophyllite to the metal material may be 1:0.3, 1:0.4, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.5, 1:1.8, 1:2, 1:2.3, 1:2.5, 1:2.7, 1:2.9, 1:3, and so on.

In the present application, the pyrophyllite may be in the form of a block or a powder; in other words, the pyrophyllite may or may not be crushed or ground prior to ball milling with the metal stock.

The metal material comprises metal aluminum; in some embodiments, the metal paste may include only metal aluminum powder; in some embodiments, the metal material may further include at least one of metallic zinc, metallic tin, metallic copper, metallic nickel, metallic iron, and metallic manganese. The mixed metal of any one of metal zinc, metal tin, metal copper, metal nickel, metal iron and metal manganese and metal aluminum is used as a reducing agent, the eutectic melting point is low, the reaction energy barrier is reduced, and the reaction is easier to occur; and the metal is not capable of reducing aluminum oxide.

In the embodiment where the metal material contains two or more metal elements, the metal material may be a mixture of powders of the above metals, or a powder obtained by pulverizing an alloy of two or more metals; the raw materials for forming the metal material are not limited, and the metal material contains metal aluminum and the raw materials in the metal material do not react with aluminum oxide. In the present application, the metal material is not limited to containing only the metal element, but may contain unavoidable impurities and metal oxides in which the metal element is partially oxidized.

In the present application, the metal material is a powder, and the particle diameter of the metal material may be 2mm or less. For example, the particle size of the metal material is 0-2 mm; the powder can promote the reaction of the metal aluminum and the pyrophyllite, so that the reaction of the metal aluminum and the pyrophyllite is more sufficient.

Alternatively, in some other embodiments of the present application, the metal stock may be in the form of blocks, wires, or the like.

In some embodiments of the present application, an inorganic salt may be further added during the ball milling process, and the inorganic salt serves as a temperature stabilizer, so that the system temperature is more balanced; in other words, a mixture containing pyrophyllite, a metal material, and an inorganic salt is ball-milled together.

Illustratively, the inorganic salt includes NaCl, KCl, LiCl, ZnCl₂、CaCl₂、MgCl₂And AlCl₃At least one of;

in some embodiments, the mass ratio of pyrophyllite to inorganic salt is 1 (0.1-3), for example, the mass ratio of pyrophyllite to inorganic salt may be 1:0.1, 1:0.2, 1:0.5, 1:0.9, 1:1, 1:1.3, 1:1.6, 1:1.9, 1:2, 1:2.1, 1:2.3, 1:2.5, 1:2.7, 1:3, and so forth.

In the present application, the inorganic salt is not essential, and the mixture may contain no inorganic salt.

In the embodiment of the present application, the inert atmosphere may be nitrogen, helium, argon, or the like.

In some embodiments, the mass ratio of milling balls to mixture is (10-50): 1; for example, 10: 1. 15: 1. 20: 1. 25: 1. 30: 1. 35: 1. 40: 1. 45, and (2) 45: 1. 50: 1, etc.

The material of the grinding balls is, for example, any one of corundum, zirconia, cemented carbide, stainless steel, agate, and silicon nitride.

In the present application, the size of the grinding balls and the ratio of the masses of the grinding balls of the respective sizes are not limited.

The ball milling device also comprises: and further comprising the step of preserving the heat of the ball-milled materials for more than 0.5h at 500-900 ℃ in an inert atmosphere.

For example, the temperature for heat preservation may be 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃, 800 ℃, 850 ℃, 900 ℃ or the like.

For example, the incubation time may be 0.5h, 0.8h, 1h, 2h, 3h, 5h, 6h, 11h, 14h, 20h, 30h, 40h, 62h, and the like.

The reaction of the pyrophyllite and the metal powder can be further promoted by heat preservation at 500-900 ℃, so that the reaction of the pyrophyllite and the metal powder is more sufficient.

It can be understood that in the application, the heat preservation at 500-900 ℃ is unnecessary, and the high-temperature heat preservation can not be carried out.

The method for preparing the silicon/aluminum oxide nanocomposite material based on the pyrophyllite provided by the embodiment of the application has at least the following advantages:

pyrophyllite resources are rich, pyrophyllite is used as a raw material, cost is low, reducing metal aluminum powder is caused to react with exposed silicon-oxygen tetrahedrons by ball milling, heating is not needed, and metal materials which are solid phases and pyrophyllite can be fully mixed by ball milling, so that the reaction is more thorough; the preparation method is simple, the used equipment is low in cost, the process conditions are not harsh, and a foundation is provided for large-scale preparation of the porous silicon/aluminum oxide nano composite material.

The present application also provides a silicon/aluminum oxide nanocomposite material prepared by the above method for preparing a silicon/aluminum oxide nanocomposite material based on pyrophyllite.

The silicon/aluminum oxide nanocomposite provided by the embodiment of the application has a layered porous structure, has good interface stability, has high tap density and high ion/electron transport performance, and can be used as a negative electrode material of a secondary battery.

The silicon/aluminum oxide nano composite material obtained by the method can be used for preparing a secondary battery cathode. It should be noted that, in the present application, the use of the silicon/aluminum oxide nanocomposite is not limited, and it may be used for other uses.

The application also provides a method for preparing the porous silicon/aluminum oxide nanocomposite material based on pyrophyllite, which comprises the following steps: the silicon/aluminum oxide nano composite material is adopted to react with acid solution, and then the silicon/aluminum oxide nano composite material is washed by water and dried.

In other words, in some embodiments, the silicon/aluminum oxide nanocomposite is reacted with an acid solution after the aforementioned method of preparing a silicon/aluminum oxide nanocomposite.

The silicon/aluminum oxide nanocomposite obtained with the aforementioned method for preparing a porous silicon/aluminum oxide nanocomposite based on pyrophyllite is reacted with an acid solution.

It should be noted that the material obtained after ball milling may be directly reacted with an acid solution. Or preserving the heat of the material obtained after ball milling at 500-900 ℃, and then reacting with an acid solution.

Illustratively, the acid solution includes at least one of hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid; the mass concentration of the acid solution is 1-25%, for example, the mass concentration of the acid may be 1%, 2%, 4%, 8%, 10%, 13%, 16%, 18%, 20%, 25%, etc.

Illustratively, the reaction time of the silicon/aluminum oxide nanocomposite material and the acid solution is 0.1 to 12 hours, for example, the reaction time may be 0.1 hour, 0.5 hour, 1 hour, 3 hours, 5 hours, 7 hours, 9 hours, 10 hours, 12 hours, and the like.

And after the silicon/aluminum oxide nano composite material is reacted with the acid solution, washing with water and drying.

And reacting the silicon/aluminum oxide nano composite material with an acid solution, and carrying out acid etching on the silicon/aluminum oxide nano composite material by the acid solution.

For example, in the case where the metal material contains a metal such as zinc or iron, the acid solution completely reacts with the metal such as zinc or iron in the silicon/aluminum oxide nanocomposite, and acid etching is performed on the metal such as zinc or iron.

Or the acid solution and the aluminum oxide in the silicon/aluminum oxide nano composite material also have an etching effect, and a trace amount of aluminum oxide is etched by acid under the effect of the acid solution.

Alternatively, a small amount of acid solution reacts some of the metals (e.g., zinc, iron, etc.) in the metal stock to effect etching.

Under the action of the acid solution, the pores of the silicon/aluminum oxide nano composite material are enriched, and the porous silicon/aluminum oxide nano composite material is obtained. For embodiments in which the acid solution is less reactive, the porous silicon/aluminum oxide nanocomposite may contain some unreacted metal (e.g., zinc, iron) or unreacted metal (e.g., copper).

For the embodiment that the silicon/aluminum oxide nano composite material is used for preparing the secondary battery cathode, the aluminum oxide can inhibit silicon pulverization and reduce side reaction, thereby effectively improving the cycle stability of the silicon cathode; the pore structure is beneficial to the transmission of ions, and the expansion of the battery can be effectively relieved; the metal in the silicon/aluminum oxide nano composite material can increase the conductive performance and the electron transmission performance.

For the above reasons, the present application does not limit the ratio of the acid solution to the silicon/aluminum oxide nanocomposite, and the acid solution may be in excess, may be in an amount just completely reacted, or may be in a small amount, based on the fact that the acid solution completely reacts with the metal in the silicon/aluminum oxide nanocomposite as a reference standard.

The application also provides a porous silicon/aluminum oxide nanocomposite material which is prepared by adopting the method for preparing the porous silicon/aluminum oxide nanocomposite material based on pyrophyllite.

The porous silicon/aluminum oxide nanocomposite has a rich pore structure, has a large tap density, and in some embodiments also contains a metal; if the material is used for preparing a battery cathode, the material is beneficial to improving the electron/ion transmission performance of the battery, and can inhibit the battery from swelling; more possibilities are offered for improving the battery performance.

The present application also provides a secondary battery anode comprising the above porous silicon/aluminum oxide nanocomposite or silicon/aluminum oxide nanocomposite.

In light of the above, the porous silicon/aluminum oxide nanocomposite or the silicon/aluminum oxide nanocomposite provided by the present application has a large tap density and a rich void structure; the advantages of larger tap density, good interface stability and faster electron transmission performance can be fully exerted.

The features and properties of the present application are described in further detail below with reference to examples.

Example 1

The silicon/aluminum oxide nanocomposite and the porous silicon/aluminum oxide nanocomposite provided by the embodiment are mainly prepared by the following steps:

preparation of silicon/aluminum oxide nanocomposite:

1g of pyrophyllite, 0.4g of metal aluminum powder and 28g of zirconia balls are mixed, then transferred into a zirconia ball milling tank, inert gas is filled in the zirconia ball milling tank to remove air, the ball milling tank is sealed and placed in a ball mill to react for 2 hours at the rotating speed of 700 rpm. Then the mixture obtained by the reaction is placed in a tube furnace and reacts for 10 hours at 800 ℃ under inert atmosphere.

Preparation of porous silicon/aluminum oxide nanocomposite:

washing the silicon/aluminum oxide nano composite material for 3 hours by using 15 wt% of dilute hydrochloric acid, then washing for a plurality of times and drying to obtain the porous silicon/aluminum oxide nano composite material.

FIG. 1 shows an X-ray diffraction pattern of a porous silicon/aluminum oxide nanocomposite material; FIG. 2 shows a Si 2p high resolution X-ray photoelectron spectrum of a porous silicon/aluminum oxide nanocomposite; FIG. 3 shows the Al2p high resolution X photoelectron spectrum of the porous silicon/aluminum oxide nanocomposite; FIG. 4 shows a scanning electron microscope image of a porous silicon/aluminum oxide nanocomposite material.

As can be seen from FIG. 1, the X-ray diffraction results showed only characteristic diffraction corresponding to that of silicon and α -/γ -aluminum oxide, and no other impurity phase signals, indicating that the porous silicon/aluminum oxide nanocomposite material is composed of Si and α -/γ -Al₂O₃And (4) forming.

As can be seen from fig. 2, elemental silicon exists mainly in the form of elemental Si.

As can be seen from fig. 3, the aluminum element is mainly present in the form of aluminum oxide; as can be seen from fig. 4, the porous silicon/aluminum oxide nanocomposite contains a porous-like layered structure.

The energy spectrum result shows that Si and Al elements in the material are uniformly distributed. The tap density of the porous silicon/aluminum oxide nanocomposite material of the present example was tested to be 0.69g/cm³Is much higher than that of commercial nano silicon material (about 0.16 g/cm)³)。

Example 2

The porous silicon/aluminum oxide nanocomposite provided by the embodiment is mainly prepared by the following steps:

6g of pyrophyllite, 3g of metal aluminum powder, 1.5g of metal copper powder and 210g of hard alloy pellets are mixed, then the mixture is transferred into a hard alloy ball milling tank, inert gas is filled in the hard alloy ball milling tank to remove air, the ball milling tank is sealed and placed in a ball mill to react for 4 hours at the rotating speed of 700 rpm. And after the reaction is finished, washing the obtained mixture with 15 wt% of dilute hydrochloric acid for 2 hours, then washing for several times, and drying to obtain the porous silicon/aluminum oxide nano composite material, wherein the porous silicon/aluminum oxide nano composite material contains simple substance silicon, aluminum oxide and metallic copper and is in a porous structure.

Example 3

The porous silicon/aluminum oxide nanocomposite provided by the embodiment is mainly prepared by the following steps:

6g of pyrophyllite, 3g of metal aluminum powder and 210g of hard alloy pellets are mixed, then the mixture is transferred into a hard alloy ball milling tank, inert gas is filled in the hard alloy ball milling tank to remove air, the ball milling tank is sealed and placed in a ball mill to react for 10 hours at the rotating speed of 700 rpm. And after the reaction is finished, washing the obtained mixture with 15 wt% of dilute hydrochloric acid for 2 hours, then washing for several times and drying to obtain the porous silicon/aluminum oxide nano composite material, wherein the porous silicon/aluminum oxide nano composite material is composed of simple substance silicon and aluminum oxide and is in a porous structure.

Example 4

The silicon/aluminum oxide nanocomposite provided by the embodiment is mainly prepared by the following steps:

10g of pyrophyllite, 8g of metal aluminum powder and 450g of corundum pellets are mixed, then the mixture is transferred into a corundum ball milling tank, inert gas is filled in the corundum ball milling tank to remove air, the ball milling tank is sealed, the mixture is placed in a ball mill, and the mixture reacts for 3 hours at the rotating speed of 800 rpm. And after the reaction is finished, directly taking out the silicon/aluminum oxide nano composite material, wherein the silicon/aluminum oxide nano composite material contains simple substance silicon and aluminum oxide and is in a similar layered structure.

Example 5

The porous silicon/aluminum oxide nanocomposite provided by the embodiment is mainly prepared by the following steps:

10g of pyrophyllite, 5g of metal aluminum powder, 1g of sodium chloride and 500g of hard alloy pellets are mixed, then the mixture is transferred into a hard alloy ball milling tank, inert gas is filled in the ball milling tank to remove air, the ball milling tank is sealed and placed in a ball mill to react for 1h at the rotating speed of 700rpm, and then the mixture is placed in a tubular furnace to react for 2h at the temperature of 700 ℃ under the inert atmosphere. And after the reaction is finished, washing the obtained mixture for 6 hours by using 5 wt% of dilute hydrochloric acid, then washing for several times, and finally drying to obtain the porous silicon/aluminum oxide nano composite material, wherein the porous silicon/aluminum oxide nano composite material contains simple substance silicon and aluminum oxide and is in a porous structure.

Example 6

The embodiment provides a method for preparing a silicon/aluminum oxide/copper nano composite material by utilizing pyrophyllite, a product and an application, and the method comprises the following steps:

10g of pyrophyllite, 6g of metal aluminum powder, 6.80g of metal copper powder, 0.06g of metal iron powder and 500g of stainless steel pellets are mixed, then the mixture is transferred into a stainless steel ball milling tank, inert gas is filled in the stainless steel ball milling tank to remove air, the ball milling tank is sealed and placed in a ball mill to react for 20 hours at the rotating speed of 400 rpm. And after the reaction is finished, washing the obtained mixture for 5 hours by using 8 wt% of dilute hydrochloric acid, then washing for a plurality of times, and finally drying to obtain the silicon/aluminum oxide/copper nano composite material. The porous silicon/aluminum oxide nano composite material contains simple substance silicon, aluminum oxide and metal copper, and is in a porous structure.

Example 7

Two lithium battery cell anodes provided in this example include the porous silicon/aluminum oxide nanocomposite provided in examples 1 and 2, respectively.

The preparation method of the battery cathode comprises the following steps:

mixing the porous silicon/aluminum oxide nanocomposite material provided in the embodiment 1 or 2, acetylene black and sodium alginate according to a mass ratio of 7: 1.5: 1.5, uniformly mixing, stirring to be pasty, then uniformly coating the paste on a copper foil by using a scraper, drying in vacuum, and cutting into small wafers.

A metallic lithium sheet is used as a counter electrode and a reference electrode, and the electrolyte is a 1mol/L LiPF6 solution (wherein the solvent is ethylene carbonate/dimethyl carbonate with the volume ratio of 1:1, and 10 wt% of fluorinated ethylene carbonate is added). Button cell assembly was performed in an argon glove box (water oxygen content was less than 0.1ppm) to produce two lithium cells.

The electrical properties of the batteries prepared from the materials of the above example 1 and example 2 were measured, the specific capacities at 1A/g current density were 812mAh/g and 785mAh/g, respectively, and the specific capacities after 1A/g cycling for 50 cycles were all maintained at 90% or more.

The material provided by the embodiment of the application can be used for preparing a secondary battery, and the utilization field of pyrophyllite is widened.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.