Preparation method and preparation equipment of porous silicon-based material

Abstract

The invention relates to a preparation method and preparation equipment of a porous silicon-based material, and belongs to the technical field of material preparation. The preparation method of the porous silicon-based material comprises the following steps: step S100, providing an inert carrier emulsion; s200, providing silicon-based microsphere powder, mixing and stirring the silicon-based microsphere powder and the inert carrier emulsion to obtain a mixed emulsion, and standing the mixed emulsion; s300, after standing of the mixed emulsion is completed, extracting supernatant liquid of the mixed emulsion; step S400, putting the mixed emulsion into a centrifugal reaction container, and introducing inert gas into the centrifugal reaction container to pressurize; step S500, rotating the centrifugal reaction container to uniformly distribute the mixed emulsion, and carrying out microwave radiation heating on the mixed emulsion; and step S600, repeating the step S500 to obtain the porous silicon-based material reaching the rated porosity. By adopting the preparation method, the uniformity and the preparation efficiency of the porous silicon-based material are improved, and the waste in the preparation process is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of material preparation, and in particular to a method and equipment for preparing a porous silicon-based material. Background Art

[0002] Porous silicon is a new type of one-dimensional nanophotonic crystal material with a "quantum sponge" microstructure with nano-silicon atom clusters as the skeleton. Porous silicon-based powder has broad application prospects in the fields of lithium-ion battery negative electrode materials due to its unique physical and chemical properties.

[0003] Conventional preparation methods for porous silicon-based materials include catalyst method, template method, silica sol method and electrochemical method. These preparation methods often have problems such as low reaction efficiency, poor product uniformity, and high energy consumption, which are difficult to meet the needs of large-scale industrial production. Therefore, it is of great significance to develop a porous silicon-based powder preparation technology that is efficient, has good product uniformity and is environmentally friendly. Summary of the invention

[0004] The purpose of the present application is to provide a method and equipment for preparing porous silicon-based materials in order to solve the above problems, which have high preparation efficiency, good product uniformity and less waste of materials, thereby improving the above problems.

[0005] This application is achieved through the following technical solutions: In a first aspect, the present application provides a method for preparing a porous silicon-based material, comprising: step S100: providing an inert carrier emulsion; step S200: providing silicon-based microsphere powder, mixing and stirring the silicon-based microsphere powder and the inert carrier emulsion to obtain a mixed emulsion, and allowing the mixed emulsion to stand; step S300: after the mixed emulsion has been allowed to stand, extracting the upper liquid of the mixed emulsion; step S400: placing the mixed emulsion into a centrifugal reaction container, and introducing an inert gas into the centrifugal reaction container for pressurization; step S500: rotating the centrifugal reaction container to evenly distribute the mixed emulsion, and heating the mixed emulsion by microwave radiation; step S600: repeating step S500 to obtain a porous silicon-based material with a rated porosity; wherein the inert carrier emulsion does not chemically react with the silicon-based microsphere powder, and the inert carrier emulsion and the silicon-based microsphere powder are physically infiltrated and soluble.

[0006] In the technical solution of the embodiment of the present application, after the inert carrier emulsion and the silicon-based microsphere powder are mixed and stirred, the mixed emulsion is allowed to stand to allow the silicon-based microsphere powder and the inert carrier emulsion to be fully mixed; after the mixed emulsion is allowed to stand for a period of time, the upper liquid of the mixed emulsion is extracted for subsequent reactions. Since the sizes of the silicon-based microspheres are uneven, the weight of the silicon-based microspheres is proportional to the size of the silicon-based microspheres. The larger silicon-based microspheres will settle to the bottom of the mixed emulsion faster under the action of gravity, and the smaller silicon-based microspheres will settle slower. The smaller silicon-based microspheres are also suspended in the mixed emulsion after the mixed emulsion is allowed to stand. The upper liquid containing the smaller silicon-based microspheres in the mixed emulsion is taken away, so that the remaining Most of the mixed emulsion contains relatively large silicon-based microspheres. This step screens the consistency of the size of the silicon-based microspheres, so that the size of the porous silicon-based microspheres obtained subsequently is relatively consistent; step S400 introduces an inert gas into the centrifugal reaction container for pressurization. On the one hand, the inert gas is used to form an inert reaction environment inside the centrifugal reaction container to prevent the silicon-based microsphere powder from undergoing adverse reactions such as oxidation at high temperature and reduce the loss of the silicon-based microsphere powder. On the other hand, by increasing the pressure, the boiling temperature of the mixed emulsion is increased, so that the water in the mixed emulsion explodes under the action of highly focused microwave energy to release more impact energy, which is helpful to form more porous structures; step S50 0 rotating the centrifugal reaction container, and subjecting the mixed emulsion to microwave radiation heating, the mixed emulsion is evenly distributed on the inner wall of the centrifugal reaction container, so that the mixed emulsion at each location can evenly and fully receive the energy of microwave radiation, the highly focused microwave energy causes the water in the mixed emulsion that contacts the silicon-based microsphere powder to explode to form impact energy, and the silicon-based microsphere powder is transformed into porous silicon-based microspheres after repeated impacts, the water in the mixed emulsion can contact various locations of the silicon-based microspheres and explode under the action of microwave energy to energize them, so that a large number of holes appear evenly on the silicon-based microspheres, and the porous silicon-based material obtained has good uniformity; step S600 repeatedly rotating the centrifugal reaction container and subjecting the mixed emulsion to microwave radiation heating, the mixed emulsion is evenly distributed on the inner wall of the centrifugal reaction container, so that the mixed emulsion at each location can evenly receive the energy of microwave radiation, and the mixed emulsion is evenly distributed on the inner wall of the centrifugal reaction container, so that the mixed emulsion can evenly receive the energy of microwave radiation, and the mixed emulsion is evenly distributed on the inner wall of the centrifugal reaction container ... The step of subjecting the mixed emulsion to microwave radiation heating further improves the porosity of the silicon-based microspheres until a porous silicon-based material (i.e., porous silicon-based microspheres) with a rated porosity is obtained. When the porous silicon-based material preparation method is used to prepare the porous silicon-based material, the silicon-based microsphere powder can fully react under repeated microwave radiation heating, and the reaction rate is higher than that of conventional preparation technology. A larger amount of porous silicon-based material can be prepared in a single preparation, thereby having a higher preparation efficiency and good uniformity of the prepared product. The inert carrier emulsion used in the preparation process can be reused, and the inert carrier emulsion will not chemically react with the silicon-based microsphere powder to cause self-loss, and less material is lost in the preparation process, which is more environmentally friendly.

[0007] In some embodiments, the radiation direction of microwave radiation heating is configured to reciprocate forward and reverse rotation relative to the centrifugal reaction container based on the rotation direction of the centrifugal reaction container to scan the mixed emulsion in the centrifugal reaction container; the speed of scanning the mixed emulsion in the radiation direction of microwave radiation heating is 5rad / min~10rad / min.

[0008] In the technical solution of the embodiment of the present application, the rotation direction of the centrifugal reaction container in the radiation direction of microwave radiation heating reciprocates relative to the centrifugal reaction container to scan the mixed emulsion evenly distributed on the inner wall of the centrifugal reaction container, and the speed of scanning the mixed emulsion in the radiation direction of microwave radiation heating is 5rad / min~10rad / min, ensuring that microwave energy acts evenly on the silicon-based microsphere powder in the mixed emulsion, thereby achieving efficient heating and uniform reaction of the mixed emulsion.

[0009] In some embodiments, repeating step S500 includes: the centrifuge reaction container is configured to reciprocately stop and rotate.

[0010] In the technical solution of the embodiment of the present application, after the centrifugal reaction container rotates for a period of time, the silicon-based microsphere powder in the mixed emulsion will move at a uniform speed according to the rotation direction and speed of the centrifugal reaction container. The centrifugal reaction container is configured to stop and rotate reciprocally. When the centrifugal reaction container stops rotating, the movement state of the silicon-based microsphere powder in the mixed emulsion can be interrupted, making the movement of the silicon-based microsphere powder more chaotic and disordered. The silicon-based microsphere powder can receive microwave energy from all angles and positions, and the holes can be evenly distributed in the silicon-based microspheres.

[0011] In some embodiments, repeating step S500 includes: controlling a rotation parameter of the centrifugal reaction container to allow the mixed emulsion to self-mix; wherein the rotation parameter is a rotation angle, a rotation center, or a rotation axis.

[0012] In the technical solution of the embodiment of the present application, after the centrifugal reaction container rotates for a period of time, the silicon-based microsphere powder in the mixed emulsion will move at a uniform speed according to the rotation direction and speed of the centrifugal reaction container. The rotation parameters of the centrifugal reaction container are controlled to continuously change the motion state of the mixed emulsion, so that the movement of the silicon-based microsphere powder becomes more chaotic and disordered. The silicon-based microsphere powder can receive microwave energy from all angles and positions, and the pores can be evenly distributed in the silicon-based microspheres, thereby improving the porosity of the prepared porous silicon-based material.

[0013] In some embodiments, the size of the silicon-based microsphere powder is micrometer-sized, and the silicon-based microsphere powder is SiOx microsphere powder or silicon powder.

[0014] In the technical solution of the embodiment of the present application, the size of the silicon-based microsphere powder is in the micron level. Taking lithium-ion batteries as an example, when the silicon-based microsphere powder is used as the negative electrode material of the battery, the size of the silicon-based microsphere powder itself is relatively small, and the volume expansion of the negative electrode material layer of the battery caused by expansion after absorbing lithium ions is relatively small, thereby reducing the risk of safety accidents caused by the expansion of the negative electrode material of the battery.

[0015] In some embodiments, the mixed emulsion is allowed to stand for 10 to 15 minutes.

[0016] In the technical solution of the embodiment of the present application, the mixed emulsion is left to stand for 10 to 15 minutes, so that the larger silicon-based microspheres in the mixed emulsion can settle to the bottom of the mixed emulsion, and the smaller silicon-based microspheres are still suspended in the upper part of the mixed emulsion. The subsequent operation of extracting the upper liquid of the mixed emulsion can screen out the smaller silicon-based microspheres in the mixed emulsion, so that the size of the porous silicon-based microspheres obtained after subsequent operations is relatively consistent.

[0017] In some embodiments, step S300 includes: when precipitation occurs in the mixed emulsion, extracting the upper layer of liquid of the mixed emulsion to the top surface of the precipitation.

[0018] In the technical solution of the embodiment of the present application, when precipitation occurs in the mixed emulsion, the precipitate contains a large amount of silicon-based microsphere powder and can settle to form a precipitate. The silicon-based microspheres contained in the precipitate are relatively large in size. By extracting the upper liquid of the mixed emulsion to the top surface of the precipitate, the silicon-based microspheres that are smaller in size than those that are insufficient to form a precipitate can be screened out.

[0019] In some embodiments, step S500 includes: the thickness of the mixed emulsion evenly distributed in the centrifugal reaction container is 1 cm to 3 cm; the temperature of the mixed emulsion when heated by microwave radiation is 300° C. to 400° C., and the heating time is 5 h to 8 h.

[0020] In the technical solution of the embodiment of the present application, the thickness of the mixed emulsion evenly distributed in the centrifugal reaction container satisfies 1 cm to 3 cm, so that the moisture around the silicon-based microspheres in various places in the centrifugal reaction container can receive sufficient microwave energy, so that the quality of the subsequently produced porous silicon-based material is stable; the temperature of the mixed emulsion when heated by microwave radiation is 300°C to 400°C, and the heating time is 5h to 8h, so that the mixed emulsion can fully react in the centrifugal reaction container, so that the subsequently produced porous silicon-based material has good uniformity and high porosity.

[0021] In some embodiments, the internal pressure of the centrifugal reaction container after the inert gas is introduced is 0.5 MPa to 0.8 MPa.

[0022] In the technical solution of the embodiment of the present application, the boiling point of the mixed emulsion is proportional to the internal pressure of the reaction container. The internal pressure of the centrifugal reaction container during operation satisfies 0.5MPa~0.8MPa, which increases the boiling point of the mixed emulsion and helps to improve the porosity of the silicon-based microspheres.

[0023] In the second aspect, the present application provides a porous silicon-based material preparation device, which includes a bracket, a centrifugal reaction container, a first control module and a directional microwave generating assembly; the centrifugal reaction container is rotatably arranged on the bracket, the centrifugal reaction container is used to contain a mixed emulsion, the centrifugal reaction container is provided with a feed port, a discharge port and a first pump, the first pump is used to pump an inert gas into the centrifugal reaction container; the first control module controls the centrifugal reaction container to rotate or stop on the bracket, and the first control module also controls the rotation parameters of the centrifugal reaction container; the directional microwave generating assembly includes a microwave generating unit and a second control module, the microwave generating unit is arranged on the inner side of the centrifugal reaction container, and the second control module controls the microwave generating unit to reciprocate forward and reverse rotation relative to the centrifugal reaction container based on the rotation direction of the centrifugal reaction container; wherein the inner wall of the centrifugal reaction container is a curved surface.

[0024] In the technical solution of the embodiment of the present application, a mixed emulsion formed by mixing an inert carrier emulsion and a silicon-based microsphere powder is placed in a centrifugal reaction container through a feed port. After the centrifugal reaction container is closed, a first pump pumps an inert gas into the centrifugal reaction container to make the internal pressure of the centrifugal reaction container relatively large (satisfying 0.5MPa~0.8MPa). Then, the centrifugal reaction container is rotated under the control of a first control module so that the mixed emulsion is evenly distributed on the inner wall of the centrifugal reaction container for centrifugal reaction. The first control module controls the centrifugal reaction container to rotate and stop cyclically, or the first control module controls the rotation parameters of the centrifugal reaction container to continuously change. The mixed emulsion is self-mixed; the microwave generating unit rotates synchronously with the rotation of the centrifugal reaction container, and then the second control module controls the microwave generating unit to reciprocate forward and reverse rotation relative to the centrifugal reaction container based on the rotation direction of the centrifugal reaction container, so that the radiation direction of the microwave emitted by the microwave generating unit repeatedly scans the mixed emulsion on the inner wall of the centrifugal reaction container, so that the mixed emulsion at various locations on the inner wall of the centrifugal reaction container can receive sufficient microwave energy; the inner wall of the centrifugal reaction container is a curved surface, so that the mixed emulsion can be evenly spread on the inner wall of the centrifugal reaction container, which helps to improve the centrifugal reaction efficiency of the mixed emulsion.

[0025] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic block diagram of a method for preparing a porous silicon-based material provided in some embodiments of the present application; Figure 2 A schematic block diagram of a method for preparing a porous silicon-based material provided in some other embodiments of the present application; Figure 3 A schematic block diagram of a method for preparing a porous silicon-based material provided in some other embodiments of the present application; Figure 4 A schematic diagram of the structure of the porous silicon-based material prepared in some embodiments of the present application; Figure 5 A schematic diagram of the structure of the porous silicon-based material prepared in some other embodiments of the present application; Figure 6 A top view of the preparation of porous silicon-based materials provided in some embodiments of the present application; Figure 7 for Figure 6 Cross-sectional view at AA in the middle.

[0028] Icons: 1- bracket; 2- centrifugal reaction container; 20- feed port; 21- discharge port; 22- first pump; 3- first control module; 4- directional microwave generating assembly; 40- microwave generating unit; 41- second control module. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

[0031] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0032] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0033] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0034] The term "multiple" as used in the present application refers to more than two (including two). Similarly, the term "multiple groups" refers to more than two groups (including two groups), and the term "multiple sheets" refers to more than two sheets (including two sheets).

[0035] The porous silicon-based material prepared by the preparation method and preparation equipment provided in this application can be applied to various fields. This application describes the application of the porous silicon-based material as the negative electrode active material layer of a battery component as an example.

[0036] The battery cell includes an electrode assembly and an electrolyte. The electrode assembly is composed of a positive electrode sheet, a negative electrode sheet and a separator. The battery cell mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode collector. The positive electrode collector not coated with the positive electrode active material layer protrudes from the positive electrode collector coated with the positive electrode active material layer. The positive electrode collector not coated with the positive electrode active material layer serves as the positive electrode tab. Taking lithium-ion batteries as an example, the material of the positive electrode collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide. The negative electrode sheet includes a negative electrode collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode collector. The negative electrode collector not coated with the negative electrode active material layer protrudes from the negative electrode collector coated with the negative electrode active material layer. The negative electrode collector not coated with the negative electrode active material layer serves as the negative electrode tab. The negative electrode current collector may be made of copper, and the negative electrode active material may be carbon or silicon, etc. In order to ensure that a large current is passed without melting, the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together.

[0037] When silicon is used as the negative electrode active material of a battery cell, it has a good ability to accommodate lithium ions. Silicon accommodates lithium ions by utilizing the three-dimensional bulk structure of silicon crystals to form a silicon-lithium alloy. After receiving lithium ions, silicon will undergo a large volume expansion. In order to suppress the negative impact of silicon's volume expansion on the manufactured battery, three methods are generally used to use silicon-based materials as negative electrode active materials for battery cells: nano-sizing silicon element particles, structural design, or making composite materials. Among them, porous silicon has a "quantum sponge"-like microstructure with nano-silicon atom clusters as the skeleton. When porous silicon-based materials are used as negative electrode active materials for battery cells, porous silicon can accommodate lithium ions through its own pores to alleviate its own expansion. Therefore, it has broad application prospects as a negative electrode material for lithium-ion batteries.

[0038] The inventors have noticed that conventional preparation methods for porous silicon-based materials include catalyst method, template method, silica sol method and electrochemical method. The number and distribution of pores in the porous silicon-based materials produced by these preparation methods are uneven. When these porous silicon-based materials with poor uniformity are used as negative electrode materials for lithium-ion batteries, lithium ions may accumulate at locations with fewer pores in these porous silicon-based materials to form lithium dendrites. The lithium dendrites may pierce the isolation membrane, causing direct contact between the positive and negative electrodes of the battery, and the battery may short-circuit and overheat, resulting in a safety situation. In addition, conventional preparation methods for porous silicon-based materials require the consumption of more catalytic or reaction materials, generating useless waste that may pollute the environment, thereby polluting the environment.

[0039] Based on the above considerations, in order to make the prepared porous silicon-based material have better uniformity and the preparation process is efficient and environmentally friendly, the inventors have developed a preparation method for porous silicon-based materials after in-depth research. The silicon-based microsphere powder is mixed with an inert carrier emulsion and placed in a centrifugal reaction container. The mixed emulsion is heated by microwave radiation. The highly focused microwave energy can cause the water in contact with the silicon-based microspheres to explode to form impact energy, and finally form porous silicon-based microspheres. The prepared porous silicon-based material has better uniformity; the inert carrier emulsion used in the preparation process can be reused, and there is no material loss in the preparation process, thereby reducing pollution to the environment.

[0040] According to some embodiments of the present application, optionally, Figure 1 As shown, the present application provides a method for preparing a porous silicon-based material, comprising: Step S100: providing an inert carrier emulsion; Step S200: providing silicon-based microsphere powder, mixing and stirring the silicon-based microsphere powder with an inert carrier emulsion to obtain a mixed emulsion, and allowing the mixed emulsion to stand; Step S300: After the mixed emulsion is left to stand, extract the upper liquid of the mixed emulsion; Step S400: placing the mixed emulsion into a centrifugal reaction container 2, and introducing an inert gas into the centrifugal reaction container 2 for pressurization; Step S500: rotating the centrifugal reaction container 2 to evenly distribute the mixed emulsion, and subjecting the mixed emulsion to microwave radiation heating; Step S600: repeating step S500 to obtain a porous silicon-based material with a rated porosity; The inert carrier emulsion does not chemically react with the silicon-based microsphere powder, and the inert carrier emulsion and the silicon-based microsphere powder are physically infiltrated and dissolved.

[0041] The inert carrier emulsion does not chemically react with the silicon-based microsphere powder under high temperature (300°C~400°C), high pressure (0.5MPa~0.8MPa) or normal temperature and pressure.

[0042] The inert carrier emulsion and the silica-based microsphere powder are physically infiltrated and soluble, and the infiltration is the limited fusion of the surfaces of two incompatible substances.

[0043] The silica-based microsphere powder and the inert carrier emulsion can be mixed by ultrasonic stirring (eg, stirring in an ultrasonic container).

[0044] After the inert carrier emulsion and the silicon-based microsphere powder are mixed and stirred, the mixed emulsion is allowed to stand to allow the silicon-based microsphere powder and the inert carrier emulsion to be fully mixed; after the mixed emulsion is allowed to stand for a period of time, the upper liquid of the mixed emulsion is extracted for subsequent reactions. Since the sizes of the silicon-based microspheres are uneven, the weight of the silicon-based microspheres is proportional to the size of the silicon-based microspheres. The larger silicon-based microspheres will settle to the bottom of the mixed emulsion faster under the action of gravity, and the smaller silicon-based microspheres will settle more slowly. The smaller silicon-based microspheres are also suspended in the mixed emulsion after the mixed emulsion is allowed to stand. The upper liquid containing the smaller silicon-based microspheres in the mixed emulsion is taken away, so that most of the remaining mixed emulsion contains The step is to screen the consistency of the size of the silica microspheres so that the size of the porous silica microspheres obtained subsequently is relatively consistent; step S400 is to introduce an inert gas into the centrifugal reaction container 2 for pressurization. On the one hand, the inert gas is used to form an inert reaction environment inside the centrifugal reaction container 2 to prevent the silica microsphere powder from being oxidized at high temperature and other adverse reactions, thereby reducing the loss of the silica microsphere powder. On the other hand, by increasing the pressure, the boiling temperature of the mixed emulsion is increased, so that the water in the mixed emulsion explodes under the action of the highly focused microwave energy to release more impact energy, which is helpful to form more porous structures; step S500 is to rotate the centrifugal reaction container 2 to increase the pressure. The mixed emulsion is evenly distributed on the inner wall of the centrifugal reaction container 2, so that the mixed emulsion at each location can evenly and fully receive the energy of the microwave radiation. The highly focused microwave energy causes the water in the mixed emulsion that contacts the silicon-based microsphere powder to explode to form impact energy. After repeated impacts, the silicon-based microsphere powder can become porous silicon-based microspheres. The water in the mixed emulsion can contact various locations of the silicon-based microspheres and explode under the action of the microwave energy to energize them, so that a large number of holes appear evenly on the silicon-based microspheres. The prepared porous silicon-based material has good uniformity. Step S600 repeats the rotation of the centrifugal reaction container 2 and the heating of the mixed emulsion. The step of subjecting the emulsion to microwave radiation heating further increases the porosity of the silicon-based microspheres until a porous silicon-based material (i.e., porous silicon-based microspheres) reaching a rated porosity is obtained; when the porous silicon-based material preparation method is used to prepare the porous silicon-based material, the silicon-based microsphere powder can fully react under repeated microwave radiation heating, and the reaction rate is higher than that of conventional preparation technology, and a larger amount of porous silicon-based material can be prepared in a single preparation, thereby having a higher preparation efficiency, and the uniformity of the prepared product is good. The inert carrier emulsion used in the preparation process can be reused, and the inert carrier emulsion will not chemically react with the silicon-based microsphere powder to cause self-loss, and the material loss in the preparation process is less, which is more environmentally friendly.

[0045] According to some embodiments of the present application, optionally, the radiation direction of microwave radiation heating is configured to reciprocate forward and reverse rotation relative to the centrifugal reaction container 2 based on the rotation direction of the centrifugal reaction container 2 to scan the mixed emulsion in the centrifugal reaction container 2; the speed of scanning the mixed emulsion in the radiation direction of microwave radiation heating is 5rad / min~10rad / min.

[0046] When the centrifugal reaction container 2 starts to rotate, the radiation direction of the microwave radiation heating can rotate at the same speed and in the same direction as the centrifugal reaction container 2. After the mixed emulsion is evenly distributed on the inner wall of the centrifugal reaction container 2, the radiation direction of the microwave radiation heating reciprocates relative to the centrifugal reaction container 2 based on the rotation direction of the centrifugal reaction container 2 to perform positive rotation (i.e., the rotation speed of the radiation direction of the microwave radiation heating is greater than the rotation speed of the centrifugal reaction container 2) and reverse rotation (i.e., the rotation speed of the radiation direction of the microwave radiation heating is less than the rotation speed of the centrifugal reaction container 2) to scan the mixed emulsion in the centrifugal reaction container 2.

[0047] The rotation direction of the centrifugal reaction container 2 for the radiation direction of microwave radiation heating reciprocates relative to the centrifugal reaction container 2 to scan the mixed emulsion evenly distributed on the inner wall of the centrifugal reaction container 2. The speed of scanning the mixed emulsion in the radiation direction of microwave radiation heating is 5rad / min~10rad / min, ensuring that the microwave energy acts evenly on the silicon-based microsphere powder in the mixed emulsion, thereby achieving efficient heating and uniform reaction of the mixed emulsion.

[0048] According to some embodiments of the present application, optionally, repeating step S500 includes: the centrifugal reaction container 2 is configured to stop and rotate reciprocally.

[0049] The time during which the centrifugal reaction container 2 stops rotating may be shorter than the time during which the centrifugal reaction container 2 rotates.

[0050] When the centrifugal reaction container 2 stops rotating, the microwave heating of the mixed emulsion in the centrifugal container also stops. After the centrifugal reaction container 2 rotates for a period of time, the silicon-based microsphere powder in the mixed emulsion will move at a uniform speed according to the rotation direction and speed of the centrifugal reaction container 2. The centrifugal reaction container 2 is configured to stop and rotate reciprocally. When the centrifugal reaction container 2 stops rotating, the movement state of the silicon-based microsphere powder in the mixed emulsion can be interrupted, making the movement of the silicon-based microsphere powder more chaotic and disordered. The silicon-based microsphere powder can receive microwave energy from all angles and positions, and the pores can be evenly distributed in the silicon-based microspheres, thereby improving the porosity of the prepared porous silicon-based material.

[0051] According to some embodiments of the present application, optionally, repeating step S500 includes: allowing the mixed emulsion to self-mix by controlling a rotation parameter of the centrifugal reaction container 2; wherein the rotation parameter is a rotation angle, a rotation center or a rotation axis.

[0052] The rotation parameters may include one or more of a rotation angle, a rotation center, and a rotation axis.

[0053] After the centrifugal reaction container 2 rotates for a period of time, the silicon-based microsphere powder in the mixed emulsion will move at a uniform speed according to the rotation direction and speed of the centrifugal reaction container 2. The rotation parameters of the centrifugal reaction container 2 are controlled to continuously change the motion state of the mixed emulsion, making the movement of the silicon-based microsphere powder more chaotic and disordered. The silicon-based microsphere powder can receive microwave energy from all angles and positions, and the pores can be evenly distributed in the silicon-based microspheres, thereby improving the porosity of the prepared porous silicon-based material.

[0054] According to some embodiments of the present application, optionally, the size of the silicon-based microsphere powder is in the micron level, and the silicon-based microsphere powder is SiOx microsphere powder or silicon powder.

[0055] The silicon-based microsphere powder can also be made of silicon as the main component raw material.

[0056] SiOx microsphere powder is high purity silicon oxide.

[0057] The size of silicon-based microsphere powder is in the micron level. Taking lithium-ion batteries as an example, when silicon-based microsphere powder is used as the negative electrode material of the battery, the size of the silicon-based microsphere powder itself is relatively small. After absorbing lithium ions, the volume expansion of the negative electrode material layer of the battery caused by the expansion is relatively small, reducing the risk of safety accidents caused by the expansion of the negative electrode material of the battery.

[0058] According to some embodiments of the present application, optionally, the mixing emulsion is allowed to stand for 10 to 15 minutes.

[0059] When the mixed emulsion is left to stand for less than 10 minutes, the sedimentation effect of the silica-based microsphere powder in the mixed emulsion is poor, and the subsequent operation of extracting the upper liquid of the mixed emulsion cannot effectively separate the smaller silica-based microspheres from the larger silica-based microspheres. When the mixed emulsion is left to stand for more than 15 minutes, the silica microsphere powder in the mixed emulsion is excessively precipitated, and the subsequent operation of extracting the upper liquid of the mixed emulsion cannot effectively separate the smaller silica microspheres from the larger silica microspheres. The mixed emulsion is allowed to stand for 10 to 15 minutes, so that the larger silicon-based microspheres in the mixed emulsion can settle to the bottom of the mixed emulsion, and the smaller silicon-based microspheres are still suspended on the upper part of the mixed emulsion. The subsequent operation of extracting the upper liquid of the mixed emulsion can screen out the smaller silicon-based microspheres in the mixed emulsion, so that the size of the porous silicon-based microspheres obtained after subsequent operations is relatively consistent.

[0060] According to some embodiments of the present application, optionally, step S300 includes: when precipitation occurs in the mixed emulsion, extracting the upper liquid of the mixed emulsion to the top surface of the precipitation.

[0061] When precipitation occurs in the mixed emulsion, the precipitate contains a large amount of silicon-based microsphere powder and can settle to form a precipitate. The silicon-based microspheres contained in the precipitate are relatively large in size. By extracting the upper liquid of the mixed emulsion to the top surface of the precipitate, the silicon-based microspheres that are smaller in size than those that are insufficient to form a precipitate can be screened out.

[0062] According to some embodiments of the present application, optionally, step S500 includes: the thickness of the mixed emulsion evenly distributed in the centrifugal reaction container 2 is 1 cm to 3 cm; the temperature of the mixed emulsion when heated by microwave radiation is 300° C. to 400° C., and the heating time is 5 h to 8 h.

[0063] When the thickness of the mixed emulsion uniformly distributed in the centrifugal reaction container 2 is less than 1 cm, the amount of the mixed emulsion contained in the centrifugal reaction container 2 is small, so that the amount of porous silicon-based material produced subsequently is small, which reduces the preparation efficiency of the porous silicon-based material; When the thickness of the mixed emulsion uniformly distributed in the centrifugal reaction container 2 is greater than 3 cm, it is difficult to ensure that the microwave radiation reaches the mixed emulsion that is far from the microwave emission position, resulting in a lower porosity of the silicon-based microspheres that are not radiated, making the quality of the porous silicon-based material produced subsequently poor; When the temperature of the mixed emulsion heated by microwave radiation is less than 300°C, the mixed emulsion receives less microwave energy, so that the water in contact with the silicon-based microspheres receives less microwave energy to explode and form impact energy, so that the porosity of the porous silicon-based material produced subsequently is lower; When the temperature of the mixed emulsion heated by microwave radiation is greater than 400°C, the mixed emulsion receives more microwave energy, so that the water in contact with the silicon-based microspheres receives more microwave energy and explodes to form impact energy, and the impact energy released by the explosion is larger, which may destroy the structure of the silicon-based microspheres themselves, making the quality of the porous silicon-based materials produced subsequently uncontrollable; The thickness of the mixed emulsion evenly distributed in the centrifugal reaction container 2 meets the requirement of 1 cm to 3 cm, so that the moisture around the silicon-based microspheres in various places in the centrifugal reaction container 2 can receive sufficient microwave energy, so that the quality of the porous silicon-based material produced subsequently is stable; the temperature of the mixed emulsion when heated by microwave radiation is 300° C. to 400° C., and the heating time is 5 h to 8 h, so that the mixed emulsion can fully react in the centrifugal reaction container 2, so that the porous silicon-based material produced subsequently has better uniformity and higher porosity.

[0064] According to some embodiments of the present application, optionally, the internal pressure of the centrifugal reaction container 2 after the inert gas is introduced is 0.5 MPa~0.8 MPa.

[0065] The boiling point of the mixed emulsion is proportional to the internal pressure of the reaction container. The internal pressure of the centrifugal reaction container 2 during operation satisfies 0.5 MPa to 0.8 MPa, which increases the boiling point of the mixed emulsion and helps to improve the porosity of the silicon-based microspheres.

[0066] According to some embodiments of the present application, optionally, Figures 4 to 7 As shown, the present application provides a porous silicon-based material preparation device, which includes a bracket 1, a centrifugal reaction container 2, a first control module 3 and a directional microwave generating component 4; the centrifugal reaction container 2 is rotatably arranged on the bracket 1, the centrifugal reaction container 2 is used to contain a mixed emulsion, and the centrifugal reaction container 2 is provided with a feed port 20, a discharge port 21 and a first pump 22, and the first pump 22 is used to pump an inert gas into the centrifugal reaction container 2; the first control module 3 controls the centrifugal reaction container 2 to rotate or stop on the bracket 1, and the first control module 3 also controls the rotation parameters of the centrifugal reaction container 2; the directional microwave generating component 4 includes a microwave generating unit 40 and a second control module 41, the microwave generating unit 40 is arranged on the inner side of the centrifugal reaction container 2, and the second control module 41 controls the microwave generating unit 40 to reciprocate forward and reverse rotation relative to the centrifugal reaction container 2 based on the rotation direction of the centrifugal reaction container 2; wherein, the inner wall of the centrifugal reaction container 2 is a curved surface.

[0067] The support 1 is arranged on the ground or a working platform, and the centrifugal reaction container 2 is arranged on the support 1 with a gap between the support 1 and the ground or the working platform.

[0068] The shape of the centrifugal reaction container 2 may be a sphere, and the inner space of the centrifugal reaction container 2 may also be a spherical shape.

[0069] The discharge port 21 and the feed port 20 can be respectively arranged at the bottom and the top of the centrifugal reaction container 2, so as to facilitate the feeding and discharging of the centrifugal reaction ventilation.

[0070] The mixed emulsion formed by mixing the inert carrier emulsion and the silicon-based microsphere powder is placed in the centrifugal reaction container 2 through the feed port 20. After the centrifugal reaction container 2 is closed, the first pump 22 pumps an inert gas into the centrifugal reaction container 2 to make the internal pressure of the centrifugal reaction container 2 relatively large (satisfying 0.5MPa~0.8MPa). Then, the centrifugal reaction container 2 is rotated under the control of the first control module 3 so that the mixed emulsion is evenly distributed on the inner wall of the centrifugal reaction container 2 for centrifugal reaction. The first control module 3 controls the centrifugal reaction container 2 to rotate and stop cyclically, or the first control module 3 controls the rotation parameters of the centrifugal reaction container 2 to continuously change so that the mixed emulsion is self- mixing; the microwave generating unit 40 rotates synchronously with the rotation of the centrifugal reaction container 2, and then the second control module 41 controls the microwave generating unit 40 to reciprocate forward and reverse rotation relative to the centrifugal reaction container 2 based on the rotation direction of the centrifugal reaction container 2, so that the radiation direction of the microwave emitted by the microwave generating unit 40 repeatedly scans the mixed emulsion on the inner wall of the centrifugal reaction container 2, so that the mixed emulsion at various locations on the inner wall of the centrifugal reaction container 2 can receive sufficient microwave energy; the inner wall of the centrifugal reaction container 2 is a curved surface, so that the mixed emulsion can be evenly spread on the inner wall of the centrifugal reaction container 2, which helps to improve the centrifugal reaction efficiency of the mixed emulsion.

[0071] According to some embodiments of the present application, optionally, Figure 2 As shown, the present application provides a method for preparing a porous silicon-based material, comprising: Step S100: providing an inert carrier emulsion; Step S210: providing micron-sized SiOx microsphere powder, mixing and stirring the SiOx microsphere powder with an inert carrier emulsion to obtain a mixed emulsion, and allowing the mixed emulsion to stand for 10 minutes; Step S300: After the mixed emulsion is left to stand, extract the upper liquid of the mixed emulsion; Step S410: placing the mixed emulsion into a centrifugal reaction container 2, and introducing an inert gas into the centrifugal reaction container 2 to increase the pressure to 0.6 MPa; Step S500: rotating the centrifugal reaction container 2 to evenly distribute the mixed emulsion, and subjecting the mixed emulsion to microwave radiation heating; Step S600: repeating step S500 to obtain a porous silicon-based material having a rated porosity.

[0072] This method for preparing porous silicon-based materials has the advantages of high reaction efficiency, good product uniformity, and low energy consumption. It can be widely used in fields such as lithium-ion battery negative electrode materials, and realizes the efficient and uniform preparation of porous silicon-based powders, meeting the needs of large-scale industrial production.

[0073] According to some embodiments of the present application, optionally, Figure 3As shown, the present application provides a method for preparing a porous silicon-based material, comprising: Step S100: providing an inert carrier emulsion; Step S220: providing micron-sized silicon powder, mixing and stirring the silicon powder with an inert carrier emulsion to obtain a mixed emulsion, and allowing the mixed emulsion to stand for 15 minutes; Step S300: After the mixed emulsion is left to stand, extract the upper liquid of the mixed emulsion; Step S410: placing the mixed emulsion into a centrifugal reaction container 2, and introducing an inert gas into the centrifugal reaction container 2 to increase the pressure to 0.6 MPa; Step S510: rotating the centrifugal reaction container 2 to make the mixed emulsion evenly distributed, adjusting the rotation parameters of the centrifugal reaction container 2 to make the mixed emulsion self-mixed, and subjecting the mixed emulsion to microwave radiation heating; Step S600: repeating step S500 to obtain a porous silicon-based material having a rated porosity.

[0074] The porous silicon-based material is prepared by mixing silicon powder with an inert carrier emulsion and placing the mixture into a centrifugal reaction container 2. The mixed emulsion is heated by microwave radiation. The highly focused microwave energy can cause the water in contact with the silicon powder to explode to form impact energy, and finally form porous silicon powder particles. The obtained porous silicon-based material has good uniformity and high porosity.

[0075] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing a porous silicon-based material, characterized in that: include: Step S100: providing an inert carrier emulsion; Step S200: providing silicon-based microsphere powder, mixing and stirring the silicon-based microsphere powder with the inert carrier emulsion to obtain a mixed emulsion, and allowing the mixed emulsion to stand; Step S300: After the mixed emulsion is left to stand, extracting the upper liquid of the mixed emulsion; Step S400: placing the mixed emulsion into a centrifugal reaction container, and introducing an inert gas into the centrifugal reaction container for pressurization; Step S500: rotating the centrifugal reaction container to evenly distribute the mixed emulsion, and subjecting the mixed emulsion to microwave radiation heating; Step S600: Repeat step S500 to obtain a porous silicon-based material with a rated porosity. The inert carrier emulsion does not chemically react with the silicon-based microsphere powder, and the inert carrier emulsion and the silicon-based microsphere powder are physically infiltrated and soluble.

2. The method for preparing a porous silicon-based material according to claim 1, characterized in that: The radiation direction of the microwave radiation heating is configured to reciprocate forward and reverse rotations relative to the centrifugal reaction container based on the rotation direction of the centrifugal reaction container to scan the mixed emulsion in the centrifugal reaction container; The speed of scanning the mixed emulsion in the radiation direction of the microwave radiation heating is 5 rad / min to 10 rad / min.

3. The method for preparing a porous silicon-based material according to claim 1, characterized in that: The repeating of step S500 includes: the centrifugal reaction container is configured to stop and rotate reciprocally.

4. The method for preparing a porous silicon-based material according to claim 1, characterized in that: The repeating of step S500 includes: controlling the rotation parameters of the centrifugal reaction container to allow the mixed emulsion to self-mix; The rotation parameter is a rotation angle, a rotation center or a rotation axis.

5. The method for preparing a porous silicon-based material according to claim 1, characterized in that: The size of the silicon-based microsphere powder is micrometer level, and the silicon-based microsphere powder is SiOx microsphere powder or silicon powder.

6. The method for preparing a porous silicon-based material according to claim 1, characterized in that: The time length for standing the mixed emulsion is 10 min to 15 min.

7. The method for preparing a porous silicon-based material according to claim 1, characterized in that: The step S300 includes: When precipitation occurs in the mixed emulsion, the upper layer of liquid of the mixed emulsion is extracted to the top surface of the precipitation.

8. The method for preparing a porous silicon-based material according to claim 1, characterized in that: The step S500 includes: The thickness of the mixed emulsion evenly distributed in the centrifugal reaction container is 1 cm to 3 cm; The temperature of the mixed emulsion when heated by microwave radiation is 300° C. to 400° C., and the heating time is 5 h to 8 h.

9. The method for preparing a porous silicon-based material according to claim 1, characterized in that: The internal pressure of the centrifugal reaction container after the inert gas is introduced is 0.5MPa~0.8MPa.

10. A porous silicon-based material preparation device, characterized in that: include Bracket; A centrifugal reaction container is rotatably disposed on the support, the centrifugal reaction container is used to contain the mixed emulsion, the centrifugal reaction container is provided with a feed port, a discharge port and a first pump, and the first pump is used to pump an inert gas into the centrifugal reaction container; A first control module controls the centrifugal reaction container to rotate or stop on the support, and the first control module also controls the rotation parameters of the centrifugal reaction container; A directional microwave generating assembly, comprising a microwave generating unit and a second control module, wherein the microwave generating unit is disposed inside the centrifugal reaction container, and the second control module controls the microwave generating unit to reciprocate forward and reverse rotation relative to the centrifugal reaction container based on the rotation direction of the centrifugal reaction container; Wherein, the inner wall of the centrifugal reaction container is a curved surface.

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