Photo-assisted supergravity reactor and preparation device of hydrophobically modified nano silicon

Abstract

The utility model discloses a photo-assisted supergravity reactor and a photo-assisted supergravity device, and belongs to the technical field of chemical engineering. The light-assisted supergravity reactor comprises a closed shell, a supergravity reactor, an ultraviolet light array, a first sprayer and a motor rotating shaft; the ultraviolet light array is arranged above the supergravity reactor; the first sprayer is arranged in the supergravity reactor; a motor rotating shaft is arranged at the bottom of the supergravity reactor. The preparation device of the hydrophobic modified nano silicon comprises a material mixing unit and a hydrosilylation reaction unit, wherein an outlet of the material mixing unit is communicated with an inlet of the hydrosilylation reaction unit; the hydrosilylation reaction unit comprises a photo-assisted supergravity reactor. According to the photo-assisted supergravity reactor, high homogenization, continuity and treatment capacity amplification can be realized, the bonding efficiency and uniformity of nano silicon and hydrophobic groups are effectively improved, and the problems of multiple procedures, complicated auxiliary operation, long time consumption and low production efficiency of a batch-type thermochemical modification method are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical industry, in particular to a light-assisted supergravity reactor and a preparation device for hydrophobic modified nano-silicon. Background Art

[0002] Anode material is one of the important materials for lithium-ion batteries. The rapid development of new energy industries represented by electric vehicles and large-scale energy storage has accelerated the development of high-energy-density batteries. The capacity of traditional graphite anodes is close to the theoretical limit, while silicon has a capacity of up to 3579 mAhg. -1 Its high specific capacity has made it a recognized next-generation negative electrode material. However, the severe volume expansion caused by the ultra-high specific capacity has become a key bottleneck restricting its application. Nanosizing silicon and compounding it with carbon materials are effective ways to achieve its application. However, nanosized silicon is affected by its large surface energy and surface oxygen-containing functional groups. Its dispersibility and compatibility in oil-based carbon-based precursors are poor, and surface modification is required to meet the requirements of silicon-based negative electrode material preparation process and product performance.

[0003] At present, the surface hydrophobic modification treatment of silicon-based nanopowders is mainly based on traditional thermochemical methods. The modifiers are mostly silicone and silane coupling agents, and the modified objects are also concentrated on nano-silica. The typical process is as follows:

[0004] (1) The prior art discloses that an organosiloxane and an aminosilane coupling agent are reacted at 80-140 °C for 1-2 hours under the action of a catalyst to polymerize and generate a hydrophobic treatment agent; silica and the hydrophobic treatment agent are mixed, an appropriate amount of solvent is added, and stirred for 1-2 hours. After uniform mixing, the mixture is reacted at 80-120 °C for 1-2 hours, and the hydrophobic silica is obtained after drying. In this method, the preparation of hydrophobic silica is completed in two stages: the synthesis of the hydrophobic treatment agent and the hydrophobic treatment of silica. The core processes such as the polymerization of the hydrophobic treatment agent, the mixing and dispersion of silica and the hydrophobic treatment agent, and the hydrophobic reaction of silica take more than 3 hours. Considering the temperature rise and fall of the system and other auxiliary operations, the preparation cycle of a single batch of hydrophobic silica will far exceed 3 hours, and the production efficiency per unit time is low.

[0005] (2) The prior art also discloses mixing sulfuric acid solution and hydrogen peroxide and stirring them evenly, adding fumed silica, stirring them in a water bath at 40-60 °C for 1-3 hours, filtering, and obtaining acid-treated fumed silica; adding the acid-treated fumed silica to deionized water, ultrasonically cleaning them at room temperature for 10-40 minutes, filtering, and drying them with nitrogen to obtain cleaned fumed silica; adding the cleaned fumed silica to an organic solvent, emulsifying them in an emulsifier for 10-30 minutes, and then ultrasonically dispersing them for 30-40 minutes to obtain a dispersion; adding a surface modifier and hexamethyldisilazane to the dispersion, and slowly adding a pH regulator, stirring and reacting them in a water bath at 40-80 °C for 2-12 hours to obtain a mixed dispersion; filtering the mixed dispersion under reduced pressure, washing the filter cake with deionized water 3-5 times, drying it at 60-80 °C, and grinding and dispersing it to obtain hydrophobic fumed silica. This method prepares hydrophobic silica through five main steps, namely silica surface pretreatment, separation, cleaning and drying, emulsification and dispersion, thermochemical surface treatment, filtration, washing and drying. The steps are numerous and the core process takes more than 4 hours. The pretreatment and product post-treatment steps produce a large amount of acidic wastewater and organic wastewater, and involve highly oxidizing and high-risk materials. The process safety is poor, and it is difficult to apply it to the large-scale preparation of hydrophobic nano-silicon.

[0006] The above technologies all have the problems of poor compatibility of nano-silicon, long preparation time, high reaction temperature, complex process and inability to produce continuously on a large scale. Utility Model Content

[0007] The main purpose of the utility model is to provide a light-assisted supergravity reactor and a preparation device for hydrophobic modified nanosilicon, so as to solve the problems in the prior art of hydrophobic nanosilicon using thermochemical surface modification, which takes a long time, has low efficiency, cannot be produced continuously on a large scale, and has poor compatibility between nanosilicon and oil-based carbon materials.

[0008] To achieve the above-mentioned object, according to one aspect of the present invention, a light-assisted high-gravity reactor is provided, which includes a closed shell and a high-gravity reactor, an ultraviolet array, a first sprayer and a motor shaft arranged inside the shell;

[0009] The ultraviolet light array is arranged above the supergravity reactor; the first sprayer is arranged inside the supergravity reactor; and the motor shaft is arranged at the bottom of the supergravity reactor.

[0010] Furthermore, the supergravity reactor includes a bottom plate, a cover plate and a spiral plate packing; the bottom of the spiral plate packing is connected to the bottom plate, and the top of the spiral plate packing is connected to the cover plate; the cover plate is made of a light-transmitting material.

[0011] Furthermore, the spiral plate packing is composed of a plurality of sheet-like blades erected on the bottom plate along the circumference of the bottom plate, and the plurality of blades are not connected to each other; wherein, the blades are erected on the bottom plate with their thickness direction surfaces, and the first ends of the plurality of blades are gathered around the first sprayer, and the second ends of the plurality of blades are arranged away from the first sprayer.

[0012] Furthermore, the top view contour of the blade when it is erected on the base plate is an arc.

[0013] Furthermore, the shape of the blades conforms to an Archimedean spiral.

[0014] Furthermore, the number of the blades is 8-12, the spacing between the first ends of the blades is 13-19 mm, and the spacing between the second ends of the blades is 104-157 mm.

[0015] Furthermore, the blade has a thickness of 3-5 mm, a width of 50-100 mm, and a length of 375 mm.

[0016] Furthermore, the material of the bottom plate and / or the material of the blades is polytetrafluoroethylene.

[0017] Furthermore, the cover plate is made of transparent quartz glass; and the shell is made of alloy material.

[0018] Furthermore, the first shell plate of the shell is provided with a feed port, and the second shell plate opposite to the first shell plate is provided with a discharge port and a shaft inlet; the motor shaft passes through the shaft inlet into the interior of the shell and is connected to the bottom plate; the ultraviolet light array is arranged on the inner surface of the first shell plate; the inlet of the first sprayer is connected to the feed port, and the first sprayer passes through the spiral plate packing and extends to the bottom plate.

[0019] Furthermore, the first sprayer passes through the central axis of the spiral plate packing and extends to the upper area of the bottom plate.

[0020] Furthermore, there is a distance between the cover plate and the first shell plate; and there is a distance between the bottom plate and the second shell plate.

[0021] Furthermore, the spiral plate filler and the bottom plate are integrally formed, and the spiral plate filler and the cover plate are fixed by screws.

[0022] In a second aspect, the present invention provides a device for preparing hydrophobic modified nano-silicon, which comprises the following units;

[0023] A mixing unit, for mixing active nano-silicon and liquid olefin to form a nano-silicon-olefin suspension;

[0024] The hydrosilation reaction unit is used to convert the nano-silicon-olefin suspension into hydrophobic nano-silicon under the action of photocatalysis;

[0025] The outlet of the mixing unit is connected to the inlet of the hydrosilation reaction unit;

[0026] Wherein, the hydrosilylation reaction unit includes the above-mentioned light-assisted high-gravity reactor.

[0027] Furthermore, the device also includes a plasma processing unit and a solid-liquid separation unit; the outlet of the plasma processing unit is connected to the inlet of the mixing unit; the mixing unit includes a mixing tank and a high-pressure pulse homogenizer; the outlet of the mixing tank is connected to the inlet of the high-pressure pulse homogenizer, and the outlet of the high-pressure pulse homogenizer is connected to the inlet of the hydrosilanization reaction unit; the outlet of the hydrosilanization reaction unit is connected to the inlet of the solid-liquid separation unit.

[0028] Furthermore, a stirring paddle driven by a motor is provided inside the mixing tank.

[0029] Furthermore, the crushing valve of the high-pressure pulse homogenizer is a diamond crushing valve.

[0030] Furthermore, the plasma processing unit includes a powder conveyor, a radio frequency power supply, a plasma generating coil, a rotary container and a material receiver.

[0031] Furthermore, the solid-liquid separation unit includes a filter sand core, a scraper plate is provided on the upper part of the filter sand core, the bottom of the filter sand core is connected to the vacuum pump and the gas pipeline, and a second sprayer is provided inside the filter sand core. The second sprayer is provided on the upper part of the filter sand core and is connected to the inlet of the solid-liquid separation unit.

[0032] According to a third aspect of the present invention, there is provided application of the above-mentioned reactor and device in preparing negative electrode materials for lithium-ion batteries.

[0033] By applying the technical solution of the utility model, a light-assisted high-gravity reactor and a device for preparing hydrophobically modified nanosilicon are provided. In the hydrosilation reaction, nanosilicon and liquid olefins are highly homogenized, continuous and have amplified processing capacity under the action of high gravity. This not only effectively improves the bonding efficiency and uniformity between nanosilicon and hydrophobic groups, but also solves the problems of intermittent thermochemical modification methods such as multiple processes, complicated auxiliary operations, long time consumption and low production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings in the specification, which constitute a part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention.

[0035] Figure 1 The three-dimensional structure diagram of the high gravity reactor in the embodiment of the present utility model is shown;

[0036] Figure 2 A schematic top view of a high gravity reactor in an embodiment of the present invention is shown;

[0037] Figure 3 The schematic diagram of the structure of the nano-silicon modification device in the embodiment of the present utility model is shown;

[0038] Figure 4 The schematic diagram of the modification mechanism of nano-silicon in the embodiment of the present utility model is shown;

[0039] Figure 5 The figure shows the process flow chart of nano-silicon modification in the embodiment of the present utility model.

[0040] The above drawings include the following reference numerals:

[0041] 1- Plasma treatment unit;

[0042] 2-mixing unit, 21-mixing tank, 22-high pressure pulse homogenizer, 221 crushing valve;

[0043] 3-hydrosiliconization reaction unit, 31-shell, 311-first shell plate, 312-second shell plate, 313-feed port, 314-discharge port, 32-ultraviolet light array, 33-first sprayer, 34-supergravity reactor, 341-spiral plate packing, 3411-plate blades, 342-bottom plate, 343-cover plate, 35-motor shaft;

[0044] 4-solid-liquid separation unit, 41-filter sand core, 42-second sprayer. DETAILED DESCRIPTION

[0045] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0046] In order to better implement the hydrosilation modification method, the utility model provides a light-assisted high-gravity reactor for hydrosilation reaction, which includes a closed shell and a high-gravity reactor arranged inside the shell, an ultraviolet array, a first sprayer and a motor shaft; wherein the ultraviolet array is arranged above the high-gravity reactor; the first sprayer is arranged inside the high-gravity reactor; the motor shaft is arranged at the bottom of the high-gravity reactor; Figure 1 and Figure 2 shown.

[0047] As a specific embodiment, the light-assisted high-gravity reactor includes a closed shell 31 and a high-gravity reactor 34, an ultraviolet array 32, a first sprayer 33 and a motor shaft 34 arranged inside the shell; wherein the ultraviolet array 32 is arranged above the high-gravity reactor 34; the first sprayer 33 is arranged inside the high-gravity reactor 34; the motor shaft 35 is arranged at the bottom of the high-gravity reactor 34; Figure 1 shown.

[0048] As a specific embodiment, the high gravity reactor 34 includes a bottom plate 342, a cover plate 343 and a spiral plate packing 341. The bottom of the spiral plate packing 341 is connected to the bottom plate 342, and the top of the spiral plate packing 341 is connected to the cover plate 343. The material of the cover plate 343 is a light-transmitting material, such as Figure 1 shown.

[0049] As a specific embodiment, the spiral plate packing 341 is composed of a plurality of plates 3411 blades arranged vertically on the bottom plate 342 along the circumference of the bottom plate, and the blades are not connected to each other; wherein, the blades 3411 are arranged vertically on the bottom plate 342 with their thickness direction surfaces, and the first ends of the blades are gathered around the first sprayer 33, and the second ends of the blades are arranged away from the first sprayer 33, such as Figure 1 and 2 shown.

[0050] As a specific embodiment, the top view contour of the blade when it is erected on the base plate is an arc.

[0051] As a specific embodiment, the shape of the blade conforms to the Archimedean spiral (i.e., the constant velocity spiral), such as Figure 2 shown.

[0052] As a specific embodiment, the number of the blades is 8-12, the spacing between the first ends of the blades is 13-19 mm, and the spacing between the second ends of the blades is 104-157 mm.

[0053] As a specific embodiment, the blade has a thickness of 3-5 mm, a width of 50-100 mm, and a length of 375 mm.

[0054] The number, thickness, width, length and spacing of the blades of the utility model can be matched and designed according to the size, processing capacity and processing effect of the high-gravity reactor.

[0055] As a specific embodiment, the material of the bottom plate and / or the material of the plate blades is polytetrafluoroethylene. The use of this bottom plate material can resist possible corrosion caused by the reaction raw materials.

[0056] In a specific embodiment, the cover is made of transparent quartz glass, and the housing is made of an alloy. The cover is preferably light-transmissive, allowing ultraviolet light from above to illuminate the raw materials in the reactor below for photocatalysis. Other materials with good light transmittance may also be used.

[0057] In a specific embodiment, the spiral blades and the base plate are integrally formed, and the spiral blades and the cover plate are fixed by screws. This integral structure of the blades and the base plate is more stable and less susceptible to damage during rotation. This integrated structure can be formed by carving multiple blades from a single plate, or by other methods.

[0058] As a specific embodiment, the first shell plate 311 of the shell 31 is provided with a feed port 313, and the second shell plate 312 opposite to the first shell plate 311 is provided with a discharge port 313 and a shaft inlet; the motor shaft 35 passes through the shaft inlet into the interior of the shell 31 and is connected to the bottom plate 342; the ultraviolet light array 32 is arranged on the inner surface of the first shell plate 311; the inlet of the first sprayer 33 is connected to the feed port 313, and the first sprayer 33 passes through the spiral plate filler 341 and extends to the bottom plate 342.

[0059] In a specific embodiment, the first sprayer 33 extends along the central axis of the spiral plate packing 341 to the upper area of the bottom plate. The sprayer is positioned in the center of the spiral reactor, with the spray holes positioned between the multiple plate clusters of the reactor. By spraying the reaction materials into the plate clusters, the sprayed materials land more evenly throughout the cluster, further facilitating a full photocatalytic reaction.

[0060] As a specific implementation, there is a distance between the cover plate 343 and the first shell plate 311 ; there is a distance between the bottom plate 342 and the second shell plate 312 .

[0061] The method of using the hydrosilation reaction unit of the utility model includes: setting the output wavelength of the ultraviolet array of the light-assisted high-gravity reactor and the rotation speed of the high-gravity reactor, for example, the wavelength is 254 nm and 365 nm, the power is 1-2 W cm -2 The speed of the high-gravity reactor is 1000-2000 rpm. The nano-silicon suspension is transported to the center of the spiral plate packing of the high-gravity reactor by a material pump. The packing unit radius is 30 cm, and the shape of the spiral plate packing blade monomer conforms to the Archimedean spiral (i.e., isokinetic spiral); and the suspension is evenly sprayed into droplets by a sprayer. For example, the spray flow rate of the nano-silicon-olefin suspension is 40-100 L h -1 ; and under the action of high-speed rotating spiral plate filler, a liquid film or mist-like floating matter is formed, and the hydrosilylation reaction between nano-silicon and olefins is completed through ultraviolet light-assisted catalysis. The materials after the reaction are transported to the filter-dryer through the bottom of the reaction chamber.

[0062] In order to prepare a hydrophobic modified nano-silicon, the utility model also provides a hydrophobic modified nano-silicon device, comprising the following units:

[0063] A mixing unit 2 is used to mix active nano-silicon and liquid olefin to form a nano-silicon-olefin suspension;

[0064] The hydrosilation reaction unit 3 is used to generate hydrophobic nano-silicon from the nano-silicon-olefin suspension under the action of photocatalysis;

[0065] The outlet of the mixing unit is connected to the inlet of the hydrosilation reaction unit;

[0066] Wherein, the hydrosilation reaction unit includes the above-mentioned light-assisted high-gravity reactor; Figure 3 、 Figure 1 and Figure 2 shown.

[0067] As a specific embodiment, the preparation device in the present invention also includes a plasma treatment unit 1 and a solid-liquid separation unit 4; the outlet of the plasma treatment unit 1 is connected to the inlet of the mixing unit 2; the mixing unit 2 includes a mixing tank 21 and a high-pressure pulse homogenizer 22; the outlet of the mixing tank 21 is connected to the inlet of the high-pressure pulse homogenizer 22, and the outlet of the high-pressure pulse homogenizer 22 is connected to the inlet of the hydrosilanization reaction unit 3; the outlet of the hydrosilanization reaction unit 3 is connected to the inlet of the solid-liquid separation unit 4.

[0068] As a specific embodiment, a stirring paddle driven by a motor is provided inside the mixing tank 21 .

[0069] As a specific embodiment, due to the characteristics of the nanosilicon-olefin mixture, the crushing valve of the high-pressure pulse homogenizer of the present invention is a diamond crushing valve 221. The mixing tank of the present invention is made of metal and has a motor-driven stirring paddle on top for the initial mixing of the active nanosilicon and the solvent. A wear-resistant diamond crushing valve is installed inside the high-pressure pulse homogenizer to fully disperse the active nanosilicon in the solvent to form a uniform nanosilicon suspension. The discharge port is connected to the light-assisted high-gravity reactor.

[0070] The method for using the mixing unit in the utility model includes: putting active nanosilicon into a mixing tank, adding liquid olefin in proportion, and stirring to form a nanosilicon-olefin mixed liquid; setting the working pressure of the high-pressure pulse homogenizer, for example, 140-180MPa, and conveying the nanosilicon-olefin mixed liquid to the homogenizer through a material pump. The high-intensity shear and collision generated by the high-pressure pulse and the cavitation effect can form a uniform nanosilicon suspension.

[0071] As a specific embodiment, the plasma processing unit 1 includes a powder conveyor, a radio frequency power supply, a plasma generating coil, a rotary container and a material receiver; Figure 3As shown; continuous feeding and discharging is achieved through the powder conveyor and rotation function, which is used to efficiently remove impurities on the surface of nano-silicon and make the silicon atoms on the surface of nano-silicon form Si-H bonds with hydrogen to transform into active nano-silicon.

[0072] The method for using the plasma processing unit of the present invention includes setting operating parameters such as the plasma processor gas flow rate, internal pressure, plasma power, and rotary speed, activating a powder conveyor to continuously feed nanosilicon into the plasma processor, and collecting the active nanosilicon in a collector after a predetermined residence time. For example, the plasma processor gas flow rate is 1-3 L, the hydrogen content is 5-10%, the internal pressure is 100-500 mTorr, the plasma power is 2000-5000 W, the rotary container inclination angle is 5-15 degrees, and the nanosilicon residence time is 2-10 minutes.

[0073] As a specific embodiment, the preparation device in the present invention also includes a solid-liquid separation unit 4, specifically a drying filter, which includes a filter sand core 41, a scraper plate is provided on the upper part of the filter sand core, the bottom of the filter sand core is connected to the vacuum pump and the gas pipeline, and a second sprayer 42 is provided inside the filter sand core; the inlet of the solid-liquid separation unit is connected to the outlet of the light-assisted supergravity reactor; the separation unit is used for separating nano-silicon from the solvent and drying the nano-silicon product.

[0074] More specifically, the present invention develops a method and device system for modifying nano-silicon, which uses nano-silicon and liquid olefin as raw materials, based on ultraviolet light-assisted catalytic hydrosilylation reaction, and realizes efficient preparation of surface hydrophobic modified nano-silicon through a continuous high-gravity reaction device.

[0075] The nano-silicon modification device system of this utility model is composed of the core device, the light-assisted high-gravity reactor, and auxiliary devices (plasma processor, mixing tank, high-pressure pulse homogenizer, filter-dryer, etc.), as follows:

[0076] (1) The core part of the plasma processor consists of a closed silo, a radio frequency power supply, a plasma generating coil and a rotary container. The powder conveyor and the rotary function realize continuous feeding and discharging, which is used to efficiently remove impurities on the surface of nano-silicon and convert the silicon atoms on the surface of nano-silicon into active nano-silicon by forming Si-H bonds with hydrogen.

[0077] (2) The mixing tank is made of common metal materials such as stainless steel, and has a built-in stirring paddle driven by a motor for the preliminary mixing of active nano-silicon and solvent;

[0078] (3) The high-pressure pulse homogenizer has a built-in wear-resistant diamond crushing valve, which is used to fully disperse the active nano-silicon in the solvent to form a uniform nano-silicon suspension. Its discharge port is connected to the light-assisted high-gravity reactor;

[0079] (4) The core part of the light-assisted high-gravity reactor consists of a UV array and a high-gravity reactor. The high-gravity reactor mainly includes a sprayer, a closed reaction chamber, a spiral plate packing and a high-speed motor, which is used for the continuous photocatalytic hydrosilylation reaction between active nano-silicon and olefins;

[0080] (5) The core component of the filter-dryer is a filter sand core. A scraper is provided on the top of the sand core. The bottom of the sand core is connected to a vacuum pump and a gas pipeline. Its inlet is connected to the outlet of the light-assisted high-gravity reactor. It is used for separating nanosilicon from solvent and drying nanosilicon products.

[0081] The present invention addresses the problems in the prior art of hydrophobic nano-silicon surface modification using thermochemical methods, which are time-consuming, inefficient, and incapable of continuous large-scale production, as well as the poor compatibility of nano-silicon with oil-based carbon materials. A novel modification method for highly hydrophobic nano-silicon has been developed, specifically as follows:

[0082] S1: Obtain active nano-silicon;

[0083] S2: mixing active nano-silicon and liquid olefin to obtain a nano-silicon-olefin suspension;

[0084] S3: The nano-silicon-olefin suspension undergoes a hydrosilylation reaction under the action of photocatalysis to obtain hydrophobic modified nano-silicon.

[0085] Figure 4 The nano-silicon modification mechanism diagram and Figure 5 As shown in the modification process flow chart, the utility model selects liquid olefins and active nano-silicon, and catalyzes the hydrosilylation reaction between nano-silicon and olefins with the assistance of photocatalysis. The reaction can achieve rapid bonding between the nano-silicon surface and hydrophobic groups at room temperature, with low energy consumption and greatly shortened modification treatment time compared to traditional thermochemical modification, with high efficiency. In the reaction process, the liquid olefin acts as both a modifier and a solvent, and can be completely recycled and reused, without the generation and discharge of waste liquid, thereby reducing material consumption costs and being green and environmentally friendly. More importantly, the nano-silicon modified by the method of the utility model has good compatibility with oil-based materials. After sedimentation performance testing, the nano-silicon modified by the method of the utility model has significantly higher dispersibility and suspension stability in oil-based materials than traditional thermochemically modified products.

[0086] To further develop a modified silicon material with high hydrophobicity and good compatibility with oil-based carbon precursor materials, this invention selects liquid olefins with 7 to 16 carbon atoms; preferably, liquid 1-olefins; and more preferably, at least one of 1-heptene, 1-octene, 1-nonene, and 1-decene. The olefin selection criteria for this invention are "liquid, low volatility, and low viscosity," so olefins containing 7 to 16 carbon atoms are selected. Furthermore, because the double bond of 1-olefins is at the end of the carbon chain, the double bond is opened and bonded to the silicon surface, avoiding the kinetic barrier caused by steric hindrance of the carbon chain.

[0087] In order to further improve the uniformity of the reaction mixture so as to fully react, the present invention mixes active nano-silicon and liquid olefin by means of high-pressure pulse homogenization treatment, and forms a uniform nano-silicon suspension through the high-intensity shear and collision and cavitation effect generated by the high-pressure pulse; the preferred pulse homogenization pressure is 140~180Mpa.

[0088] To achieve highly hydrophobic modified nanosilicon and high compatibility, the present invention sets the solids content of the nanosilicon-olefin suspension to 5% to 20%; preferably, the solids content is 5% to 15%. By adjusting the ratio of nanosilicon to liquid olefin, the two can fully complete the hydrosilation reaction. If the solids content is too low, production efficiency will be low; if the solids content is too high, the suspension will become a paste-like non-Newtonian fluid, making it difficult to transport, and the interior will not be exposed to light, making the hydrosilation reaction difficult.

[0089] The nano-silicon-olefin suspension is made into at least one of the forms of droplets, liquid films and mist-like floating objects, and then subjected to a hydrosilylation reaction under the action of photocatalysis; this method can promote the hydrosilylation reaction more fully.

[0090] The hydrosilation reaction is carried out in a light-assisted high-gravity reaction system; further, the light-assisted high-gravity reactor, the output wavelength and power of the ultraviolet array, and the rotation speed of the high-gravity reactor are used to transport the nanosilicon suspension to the center of the spiral plate packing of the high-gravity reactor, and evenly spray it into droplets through a sprayer. Under the action of the high-speed rotating spiral plate packing, a liquid film or mist-like floating material is formed. The hydrosilation reaction between the nanosilicon and the olefin is completed by ultraviolet-assisted catalysis. The reacted materials are transported to the filter-dryer through the bottom of the reaction chamber. Preferably, the spray flow rate of the nanosilicon-olefin suspension is 40~100 L h -1 ; The rotation speed of rotary spraying is 1000~2000 rpm.

[0091] In order to further promote the hydrosilylation reaction, ultraviolet light catalysis was used. The specific wavelength of ultraviolet light was 254nm and 365nm, and the power was 1~2 W cm -2; The hydrosilylation reaction can be further promoted under this ultraviolet catalysis.

[0092] To obtain active nanosilicon, the raw material can be purchased commercially or prepared using the following steps: The nanosilicon is activated in an inert atmosphere containing hydrogen to obtain the active nanosilicon. Since commercially available raw active nanosilicon easily oxidizes to inactive nanosilicon during transportation and storage, resulting in poor quality control, the method of activating the raw material immediately before use is more effective.

[0093] The conditions for nano-silicon activation treatment include: hydrogen and inert gas are introduced into the plasma processor, and the total gas flow rate is 1~3L min -1 , the hydrogen content is 5% to 10%, the plasma power is 2000 to 5000W, the inclination angle of the rotary container is 5 to 15 degrees; the activation pressure is 100 to 500 mTorr, the activation time is 2 to 10 minutes, and the activation temperature is 20°C to 35°C; preferably, the inert gas is argon; using the above activation conditions, high-quality and high-yield active nano-silicon can be obtained. In the specific method, the flow rate of hydrogen is 50 to 300 mL min -1 The flow rate of argon is 950~2700 mL min -1 When activating nano-silicon, the present invention does not require a specific ratio of nano-silicon to hydrogen. As long as the gas flow rate and content reach the set value, the activation equipment can meet the maximum amount of nano-silicon activation demand. The inert gas is used for explosion-proof and other safety control of the activation reaction process.

[0094] To obtain modified silicon powder, step S3 further includes: performing solid-liquid separation on the nanosilicon-olefin reaction product, drying the separated solid to obtain hydrophobic modified nanosilicon, and returning the separated liquid olefin to step S2 to mix with the active nanosilicon. Considering the small particle size, high liquid holdup, and high filtration resistance of nanosilicon, solid-liquid separation needs to be performed under negative pressure conditions. When the separated modified silicon solid accumulates to a certain thickness, a scraper can be used to break it up and reversely blow gas to dry and crush the filter cake, thereby obtaining a dispersed hydrophobic nanosilicon product.

[0095] More specifically, a nano-silicon modification method is provided, and the process flow is as follows:

[0096] (1) Setting the plasma processor's operating parameters such as gas flow, internal pressure, plasma power, and rotation speed, starting the powder conveyor to continuously feed nano-silicon into the plasma processor, and collecting the active nano-silicon in the collector after a certain residence time;

[0097] (2) Weighing active nano-silicon and putting it into a mixing tank, adding liquid olefin in proportion, and stirring to form a nano-silicon-olefin mixed liquid;

[0098] (3) Setting the working pressure of the high-pressure pulse homogenizer, delivering the nano-silicon-olefin mixture to the homogenizer through the material pump, and forming a uniform nano-silicon suspension through the high-intensity shear and collision and cavitation effect generated by the high-pressure pulse;

[0099] (4) Setting the output wavelength and power of the ultraviolet array of the light-assisted high-gravity reactor and the rotation speed of the high-gravity reactor, transporting the nano-silicon suspension to the center of the spiral plate packing of the high-gravity reactor through a material pump, and evenly spraying it into droplets through a sprayer, and forming a liquid film or mist-like floating matter under the action of the high-speed rotating spiral plate packing, completing the hydrosilylation reaction between the nano-silicon and the olefin through ultraviolet-assisted catalysis, and the reaction-completed materials are transported to the filter-dryer through the bottom of the reaction chamber;

[0100] (5) The nano-silicon-olefin mixture after the hydrosilation reaction is subjected to solid-liquid separation under negative pressure in a filter-dryer. When the solid accumulates to a certain thickness, it is broken up by a scraper and gas is blown in the reverse direction to dry and crush the filter cake, thereby obtaining a dispersed hydrophobic nano-silicon product;

[0101] (6) The olefins separated by the filter-dryer are transported to the mixing process for recycling.

[0102] The nanosilicon modification device and modification method are suitable for the photocatalytic treatment and modification of fluid-containing materials. Specifically, the nanosilicon modification method uses nanosilicon powder, argon, hydrogen, and olefins as raw materials. In the nanosilicon modification device system, the nanosilicon undergoes activation, mixing, homogenization, photocatalytic supergravity hydrosilation, filtration, and drying to obtain a hydrophobic nanosilicon product. This modification method achieves rapid bonding between the nanosilicon surface and hydrophobic functional groups through a photocatalytic supergravity hydrosilation reaction, and achieves high homogenization, continuity, and increased processing capacity through supergravity. This not only effectively improves the bonding efficiency and uniformity between the nanosilicon and the hydrophobic groups, but also addresses the issues of intermittent thermochemical modification methods, such as multiple steps, cumbersome auxiliary operations, long time consumption, and low production efficiency. Furthermore, the solvent, which serves as the modifier, can be separated and fully recycled, effectively avoiding the introduction of impurities and additional additives during the modification process, as well as the generation of waste liquid.

[0103] The above preparation method has the following advantages:

[0104] 1. High efficiency of nano-silicon modification: The nano-silicon raw materials are continuously pretreated through the plasma activation process, without the need for auxiliary operations such as separation and cleaning in traditional wet pretreatment; the continuous operation and high-throughput processing of the nano-silicon surface modification reaction are achieved through the effect of supergravity, breaking through the single-batch processing capacity limitations of traditional surface modification intermittent processes.

[0105] 2. The process conditions for nano-silicon modification are mild and the modification reaction is highly homogenized: through ultraviolet light-assisted catalysis of the hydrosilylation reaction between nano-silicon and olefins, rapid bonding between the nano-silicon surface and the hydrophobic groups is achieved at room temperature, with low energy consumption. Compared with traditional thermochemical modification, the modification treatment time is greatly shortened. In addition, the material is highly homogenized under the action of high gravity to ensure sufficient and uniform hydrosilylation reaction, achieve full combination of nano-silicon and hydrophobic groups, and ensure the consistency of hydrophobic nano-silicon products.

[0106] 3. The nano-silicon modification process is green and environmentally friendly: the modifier olefin also acts as a solvent and can be completely recycled and reused. No waste liquid is generated or discharged, which also reduces material consumption costs.

[0107] 4. The modified nano-silicon has good compatibility with oil-based materials: According to sedimentation performance tests, the dispersibility and suspension stability of the nano-silicon of the present invention in oil-based materials are significantly higher than those of traditional thermochemically modified products.

[0108] Based on the above modification method, a highly hydrophobic modified nano-silicon can be obtained, and it has good compatibility with oil-based carbon materials; therefore, the above hydrophobic modified nano-silicon can be used in lithium-ion battery negative electrode materials.

[0109] Based on the prepared highly hydrophobic modified nano-silicon, a lithium-ion battery silicon-based negative electrode material can be prepared, which is formed by dispersing nano-silicon in an oil-based carbon precursor material; in this process, the nano-silicon can be selected from the hydrophobic modified nano-silicon prepared by the method of the present invention, and the two have good compatibility, which solves the problem of incompatibility between nano-silicon and oil-based carbon materials in traditional technologies.

[0110] The present application is further described in detail below in conjunction with specific examples. These examples should not be construed as limiting the scope of protection claimed in this application. The following examples use the above-mentioned light-assisted supergravity reaction device of the present invention to carry out hydrosilylation reaction.

[0111] Example 1

[0112] Nano-silicon was loaded into the plasma processor hopper and the atmosphere was replaced at 1800 mL min -1 and 200 mL min -1Argon and hydrogen were introduced at a flow rate of 1000 W, the pressure was set to 300 mTorr, the plasma power was 4000 W, the container rotation rate was 5 rpm, and the inclination angle of the rotating container was adjusted to ~10° so that the nanosilicon residence time was about 5 min, and active nanosilicon was collected; the active nanosilicon was weighed and put into a mixing tank, and 1-octene was added and stirred to prepare a mixed solution with a solid content of 10%, and then subjected to a high-pressure pulse treatment of 180 MPa to form a uniform nanosilicon-octene suspension; the ultraviolet array of the light-assisted high-gravity reactor was set to output a wavelength of 254 nm and a power of 1 W cm -2 , the high gravity reactor speed is 1500 rpm (acceleration is 100-440 g , g is the acceleration due to gravity), with 40L h -1 The nano-silicon-octene suspension is sprayed into the light-assisted high-gravity reactor at a flow rate of 1000 rpm. The materials after the photocatalytic hydrosilylation reaction (at room temperature) are transported to the filter-dryer, in which the hydrophobic nano-silicon product is obtained by negative pressure filtration, air drying and dispersion.

[0113] Example 2

[0114] Nano-silicon was loaded into the plasma processor hopper and the atmosphere was replaced at 1900 mL min -1 and 100 mL min -1 Argon and hydrogen were introduced at a flow rate of 1000 W, the pressure was set to 300 mTorr, the plasma power was 3000 W, the container rotation rate was 5 rpm, and the inclination angle of the rotating container was adjusted to ~5° so that the nanosilicon residence time was about 10 min. Active nanosilicon was collected and obtained. Active nanosilicon was weighed and put into a mixing tank. 1-octene was added and stirred to prepare a mixed solution with a solid content of 5%. The mixture was then treated with a high-pressure pulse of 160 MPa to form a uniform nanosilicon-octene suspension. The ultraviolet array of the light-assisted high-gravity reactor was set to output a wavelength of 254 nm and a power of 2 W cm -2 , the high gravity reactor speed is 2000 rpm (acceleration is 179-783 g , g is the acceleration due to gravity), with 60L h -1 The nano-silicon-octene suspension is sprayed into the light-assisted high-gravity reactor at a flow rate of 1000 nm. The materials after the photocatalytic hydrosilylation reaction are transported to the filter-dryer, in which the hydrophobic nano-silicon product is obtained by negative pressure filtration, air drying and dispersion.

[0115] Example 3

[0116] Nano-silicon was loaded into the plasma processor hopper and the atmosphere was replaced at 2700 mL min -1 and 300 mL min -1Argon and hydrogen were introduced at a flow rate of 500 mTorr, the pressure was set to 5000 W, the plasma power was 5000 W, and the container rotation rate was 5 rpm. The inclination angle of the rotating container was adjusted to ~15° so that the nanosilicon residence time was about 2 min, and active nanosilicon was collected; the active nanosilicon was weighed and put into a mixing tank, and 1-octene was added and stirred to prepare a mixed solution with a solid content of 5%, which was then treated with a high-pressure pulse of 180 MPa to form a uniform nanosilicon-octene suspension; the ultraviolet array of the light-assisted high-gravity reactor was set to output a wavelength of 365 nm and a power of 1.5 W cm -2 , the high gravity reactor speed is 1000 rpm (acceleration is 45-196 g , g is the acceleration due to gravity), with 40L h -1 The nano-silicon-octene suspension is sprayed into the light-assisted high-gravity reactor at a flow rate of 1000 nm. The materials after the photocatalytic hydrosilylation reaction are transported to the filter-dryer, in which the hydrophobic nano-silicon product is obtained by negative pressure filtration, air drying and dispersion.

[0117] Example 4

[0118] Nano-silicon was loaded into the plasma processor hopper and the atmosphere was replaced at 950 mL min -1 and 50 mL / min -1 Argon and hydrogen were introduced at a flow rate of 100 mTorr, the plasma power was 2000 W, and the container rotation rate was 5 rpm. The inclination angle of the rotating container was adjusted to ~10° so that the nanosilicon residence time was about 5 min, and active nanosilicon was collected. Active nanosilicon was weighed and put into a mixing tank, and 1-decene was added and stirred to prepare a mixed solution with a solid content of 20%. The mixture was then treated with a high-pressure pulse of 140 MPa to form a uniform nanosilicon-decene suspension. The ultraviolet array of the light-assisted high-gravity reactor was set to output a wavelength of 365 nm and a power of 2 W cm -2 , the high gravity reactor speed is 2000 rpm (acceleration is 179-783 g , g is the acceleration due to gravity), with 80L h -1 The nano-silicon-decene suspension is sprayed into the light-assisted high-gravity reactor at a flow rate of 1000 nm. The materials after the photocatalytic hydrosilylation reaction are transported to the filter-dryer, in which the hydrophobic nano-silicon product is obtained by negative pressure filtration, air drying and dispersion.

[0119] Example 5

[0120] Nano-silicon was loaded into the plasma processor hopper and the atmosphere was replaced at 1800 mL min -1 and 200 mL min -1Argon and hydrogen were introduced at a flow rate of 1000 W, the pressure was set to 300 mTorr, the plasma power was 4000 W, the container rotation rate was 5 rpm, and the inclination angle of the rotating container was adjusted to ~10° so that the nanosilicon residence time was about 5 min, and active nanosilicon was collected; active nanosilicon was weighed and put into a mixing tank, 1-decene was added and stirred to prepare a mixed solution with a solid content of 15%, and then a uniform nanosilicon-decene suspension was formed by high-pressure pulse treatment at 180 MPa; the ultraviolet array of the light-assisted high-gravity reactor was set to output a wavelength of 254 nm and a power of 2 W cm -2 , the high gravity reactor speed is 1500 rpm (acceleration is 100-440 g , g is the acceleration due to gravity), with 100L h -1 The nano-silicon-decene suspension is sprayed into the light-assisted high-gravity reactor at a flow rate of 1000 nm. The materials after the photocatalytic hydrosilylation reaction are transported to the filter-dryer, in which the hydrophobic nano-silicon product is obtained by negative pressure filtration, air drying and dispersion.

[0121] Comparative Example

[0122] A certain amount of 5% nanosilicon ethanol dispersion was prepared, an equal amount of 40% hydrofluoric acid solution was added, and the mixture was stirred for 30 min for pretreatment activation. The mixture was then filtered, washed, and dried. The activated nanosilicon was weighed and mixed with xylene and ultrasonically treated for 30 min to prepare a 10% nanosilicon-xylene suspension. Diethyl carbonate (15% by mass of the nanosilicon) was added, stirred evenly, and heated to 80 °C for 2 h. Polydimethylsiloxane (15% by mass of the nanosilicon) was then added and the mixture was kept warm at 80 °C for another 2 h. The solid matter was filtered out and washed using Soxhlet extraction with n-hexane as the solvent. The hydrophobic nanosilicon sample was obtained after drying.

[0123] In this embodiment of the utility model, hydrophobic nanosilicon was prepared using nanosilicon with an average particle size of 100 nm and 1-octene / 1-decene as raw materials. The hydrophobic nanosilicon sample was weighed and dispersed in diesel to prepare a stable suspension with a mass fraction of 1%. The sedimentation coefficient was measured by analytical centrifugation technology (equipment model LUMiSizer 611, rotation speed 3000 rpm, light source wavelength 870 nm) to evaluate the hydrophobic modification effect.

[0124] Table 1. Sedimentation coefficient of modified nano-silicon in diesel

[0125]

[0126] The test results in Table 1 show that the average sedimentation coefficient of the hydrophobic modified nano-silicon prepared in Examples 1 to 5 of the present invention in diesel is 1.54×10 3 ~1.63×10 3; The sedimentation coefficient of unmodified nano-silicon is 2.05×10 4 , which is much larger than the sedimentation coefficient of the modified nano-silicon of the present invention. The lower the sedimentation coefficient, the higher the dispersibility and suspension stability of the sample in the oil-based solvent, which reflects the higher compatibility between the sample surface and the oil-based solvent molecules. The above shows that the hydrophobic modified nano-silicon obtained by the method of the present invention can significantly improve the hydrophobicity of nano-silicon and its compatibility with oil-based carbon materials.

[0127] The average sedimentation coefficient of the hydrophobic nano-silicon prepared by the traditional thermochemical method in the comparative example is 1.95×10 3 The average sedimentation coefficient of the hydrophobic modified nano-silicon prepared in Examples 1 to 5 of the present invention in diesel is 1.54×10 3 ~1.63×10 3 Compared with the two, the hydrophobic modified nano-silicon prepared by the method of the present invention has better dispersion, suspension and compatibility in oil-based carbon materials represented by diesel. Since diesel is usually used as a regulator in the processing of oil-based carbon-based raw materials, diesel is used as a representative test, which can reflect the compatibility of hydrophobic nano-silicon with oil-based carbon-based raw materials. In addition, oil-based carbon-based raw materials usually have very high viscosity and poor light transmittance, and oil-based carbon-based raw materials cannot be used directly for testing. The above shows that the innovative modification method of the present invention is better than the traditional thermochemical method, and can further improve the hydrophobicity of modified nano-silicon and its compatibility with oil-based carbon materials.

[0128] The thermochemical modification method in the comparative example frequently uses various additives and the process is cumbersome, such as adding corrosive hydrofluoric acid solution, xylene, diethyl carbonate, polydimethylsiloxane, n-hexane solvent, etc., and too many reactants are added, which need to be removed and cleaned later, polluting the environment, wasting materials, and increasing costs.

[0129] The comparative example reaction was carried out at 80°C for 2 hours; the present method is carried out at room temperature. This method is more energy-efficient and has simpler overall steps. The comparative example method cannot achieve continuous large-scale production; however, the present method, equipped with the corresponding apparatus, can achieve continuous large-scale production, further improving production efficiency.

[0130] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A light-assisted high-gravity reactor, characterized in that: The light-assisted high-gravity reactor comprises a closed shell and a high-gravity reactor, an ultraviolet array, a first sprayer and a motor shaft arranged inside the shell; Wherein, the ultraviolet light array is arranged above the high-gravity reactor; the first sprayer is arranged inside the high-gravity reactor; and the motor shaft is arranged at the bottom of the high-gravity reactor.

2. The light-assisted high-gravity reactor according to claim 1, characterized in that: The high-gravity reactor includes a bottom plate, a cover plate and a spiral plate packing; the bottom of the spiral plate packing is connected to the bottom plate, and the top of the spiral plate packing is connected to the cover plate; and / or the cover plate is made of a light-transmitting material.

3. The light-assisted high-gravity reactor according to claim 2, characterized in that: The spiral plate packing is composed of a plurality of sheet-like blades vertically arranged on the bottom plate along the circumference of the bottom plate, and the plurality of blades are not connected; The blades are erected on the bottom plate with their surfaces in the thickness direction, and the first ends of a plurality of the blades are gathered around the first sprayer, and the second ends of a plurality of the blades are arranged away from the first sprayer.

4. The light-assisted high-gravity reactor according to claim 3, characterized in that: The top view contour shape of the plate blade when it is erected on the bottom plate is an arc.

5. The light-assisted high-gravity reactor according to claim 3, characterized in that: The number of the blades is 8-12, the spacing between the first ends of the blades is 13-19 mm, and the spacing between the second ends of the blades is 104-157 mm; the thickness of the blades is 3-5 mm, the width is 50-100 mm, and the length is 375 mm; And / or, the shape of the blade complies with an Archimedean spiral.

6. The light-assisted high-gravity reactor according to claim 3, characterized in that: The first shell plate of the housing is provided with a feed port, and the second shell plate opposite to the first shell plate is provided with a discharge port and a shaft inlet; the motor shaft passes through the shaft inlet and enters the interior of the housing and is connected to the bottom plate; And / or, the ultraviolet light array is arranged on the inner surface of the first shell; and / or, the first sprayer passes through the central axis of the spiral plate packing and extends to the upper area of the bottom plate; And / or, there is a distance between the cover plate and the first shell plate; there is a distance between the bottom plate and the second shell plate; And / or, the spiral plate filler and the bottom plate are integrally formed, and the spiral plate filler and the cover plate are fixed by screws.

7. The light-assisted high-gravity reactor according to claim 6, characterized in that: The material of the bottom plate and / or the material of the plate blades is polytetrafluoroethylene; And / or, the cover plate is made of transparent quartz glass; the shell is made of alloy material; And / or, the inlet of the first sprayer is communicated with the feed port, and the first sprayer passes through the spiral plate packing and extends to the bottom plate.

8. A device for preparing hydrophobically modified nano-silicon, characterized in that: The device comprises the following units: A mixing unit, for mixing active nano-silicon and liquid olefin to form a nano-silicon-olefin suspension; A hydrosilation reaction unit, used for converting the nano-silicon-olefin suspension into hydrophobic nano-silicon under the action of photocatalysis; The outlet of the mixing unit is connected to the inlet of the hydrosilation reaction unit; Wherein, the hydrosilylation reaction unit comprises the light-assisted high-gravity reactor according to any one of claims 1 to 7.

9. The device for preparing hydrophobic modified nano-silicon according to claim 8, characterized in that: The preparation device further includes a plasma processing unit and a solid-liquid separation unit; the outlet of the plasma processing unit is connected to the inlet of the mixing unit; And / or, the mixing unit includes a mixing tank and a high-pressure pulse homogenizer; the outlet of the mixing tank is connected to the inlet of the high-pressure pulse homogenizer, and the outlet of the high-pressure pulse homogenizer is connected to the inlet of the hydrosilation reaction unit; the outlet of the hydrosilation reaction unit is connected to the inlet of the solid-liquid separation unit.

10. The device for preparing hydrophobic modified nano-silicon according to claim 9, characterized in that: The plasma processing unit includes a powder conveyor, a radio frequency power supply, a plasma generating coil, a rotary container and a material receiver; And / or, the solid-liquid separation unit includes a filter sand core, a scraper is provided on the upper portion of the filter sand core, a vacuum pump and a gas pipeline are connected to the bottom of the filter sand core, a second sprayer is provided inside the filter sand core, and the second sprayer is provided on the upper portion of the filter sand core and is connected to the inlet of the solid-liquid separation unit; And / or, a stirring paddle driven by a motor is provided inside the mixing tank; And / or, the crushing valve of the high-pressure pulse homogenizer is a diamond crushing valve.

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