Method and device for producing silicon monoxide or core-doped silicon monoxide powder

Abstract

The invention relates to a production method and device for silicon monoxide or core-doped silicon monoxide powder, and the production method comprises the following steps: (1) putting a reaction material for generating silicon monoxide into a heating cavity, and heating to generate silicon monoxide steam; (2) when the generation amount of the silicon monoxide steam is enough, the silicon monoxide steam overflows into a condensation granulation cavity, and meanwhile, a nucleating agent is scattered above the silicon monoxide steam and falls down by gravity; and (3) in the falling process of the nucleating agent, condensing the silicon monoxide steam on the surface of the nucleating agent, and forming silicon monoxide powder in which the core of the nucleating agent is coated with a silicon monoxide shell layer. According to the invention, the reaction of the silicon monoxide steam can be carried out in a completely closed and vacuum or atmosphere environment without blowing out for charging or blowing out for replacing vulnerable accessories, so that the production efficiency is improved, the energy consumption is reduced and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon oxide production equipment, and relates to a method and a device for producing silicon oxide or core-doped silicon oxide powder. Background Art

[0002] As an emerging mobile energy storage device, lithium-ion batteries have become a key component of portable electronic devices, electric vehicles, etc. With the update of social needs, the capacity and long life requirements of lithium-ion batteries are constantly increasing. The existing low-capacity lithium-ion battery negative electrode materials are mostly based on graphite negative electrode materials, and their specific capacity is only 375mAhg -1 , which is far from meeting the market demand for new lithium batteries.

[0003] Silicon oxide has been the focus of research on negative electrode materials with high specific capacity and cycle life as market demand. Although its specific capacity meets the requirements, its use is still limited due to its low first coulombic efficiency, high energy consumption, and low production efficiency. The traditional solution to the low first coulombic efficiency and cycle life is to add a pre-lithiation agent to silicon oxide for pre-lithiation, thereby increasing the first coulombic efficiency. Or use titanium oxide to dope silicon oxide to extend its cycle life. However, these solutions are costly, or the synthesis process is cumbersome, and the repeated heating and processing of raw materials consumes a lot of energy. The process conditions for the preparation of silicon oxide are relatively harsh, requiring 1200℃~1500℃ and 0.01~0.001 vacuum conditions. Intermittent production requires the furnace body to continuously rise to high temperature, reduce pressure, and then cool down to take materials, resulting in huge energy consumption losses. High temperature and low pressure also make traditional equipment design unable to meet continuous production requirements due to wear at high temperature. Most silicon oxide production equipment is in the form of only one or two chambers. During production, the raw materials in the heating chamber are heated and depressurized to gasify and overflow, and cooled and agglomerated in the cooling chamber. This kind of agglomerate is huge and hard, and needs to be roughly broken by a professional jaw crusher, and then ground before further processing. The overall production process is interrupted, and it needs to be cooled down, re-added with raw materials, and then vacuumed to continue production. The finished product also needs to be cooled down before being taken out. This greatly affects production efficiency. The scraping powder method scrapes on the cooling chamber or collector, causing the scraper to wear, and the finished product has many impurities, which is not suitable for continuous production.

[0004] A Chinese patent (CN113620301A) proposes a method and device for producing silicon oxide. The patent dries silicon-containing substances such as silicon oxide, silicon element, silicon-containing gas (liquid), incompletely oxidized silicon, etc. into solid silicon powder, further oxidizes (including incomplete oxidation), reduces or adds silicon dioxide to reach an ideal ratio close to the formation of silicon oxide, and then forms silicon oxide gas under conditions that are conducive to the overflow of silicon oxide, such as high temperature, and then condenses the gas into rod-shaped, plate-shaped, granular or powdered silicon oxide. In this method, when the silicon oxide gas condenses, it will condense and form blocks with the cold part of the equipment, causing equipment blockage or insufficient powder production, and thus long-term continuous production is not possible.

[0005] The Chinese patent (CN109888246A) proposes a silicon oxide composite negative electrode material with a gradient structure, a core-shell structure consisting of a silicon dioxide layer, a silicon oxide material layer and a carbon coating layer distributed from the inside to the outside. It has a certain service life and specific capacity, but the production process is condensed on a collector, then crushed and condensed on the collector repeatedly, the production process is cumbersome, the first efficiency has not been greatly improved, and continuous production is impossible. Summary of the invention

[0006] The purpose of the present invention is to provide a method and device for producing silicon oxide or core-doped silicon oxide powder, so as to realize efficient and continuous production and preparation of silicon oxide, especially core-doped silicon oxide powder.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] One of the technical solutions of the present invention provides a production process for silicon dioxide or core-doped silicon dioxide powder, comprising the following steps:

[0009] (1) placing a reaction material for producing silicon oxide in a heating chamber and heating the reaction material to produce silicon oxide vapor;

[0010] (2) When the amount of silicon oxide vapor generated is sufficient, it overflows into the condensation granulation chamber, and at the same time, the nucleating agent is spread from above the silicon oxide vapor and falls by gravity;

[0011] (3) During the falling process of the nucleating agent, silicon oxide vapor condenses on the surface of the nucleating agent, and silicon oxide powder is formed with a silicon oxide shell covering the nucleating agent core.

[0012] Furthermore, in step (1), the reaction material is silicon monoxide, or a silicon-containing material used for reacting to generate silicon monoxide vapor.

[0013] Furthermore, in step (1), the heating temperature is 1000°C to 1500°C.

[0014] Furthermore, in step (1), the vacuum degree in the heating chamber is maintained at 0.001Pa to 100Pa.

[0015] Furthermore, in step (2), the temperature of the nucleating agent before spreading is controlled within a range of -40°C to 1000°C.

[0016] Furthermore, in step (2), the nucleating agent is a metal, an alkali metal, a metal mixture, a metal oxide, a non-metal oxide or a nitride.

[0017] Furthermore, in step (2), the nucleating agent is silicon dioxide, silicon, silicon oxide, titanium dioxide, lithium metal, lithium-containing compounds or lithium oxides, etc. Specifically, when the nucleating agent is silicon oxide, the generated powder is pure silicon oxide powder, and when the nucleating agent is other condensation cores, it is silicon oxide powder with core doping.

[0018] Furthermore, in step (2), the particle size of the nucleating agent is 0.1 nm to 100 μm, and preferably, the particle size range is 5 nm to 5 μm.

[0019] The second technical solution of the present invention provides a production device for silicon oxide or core-doped silicon oxide powder, which is used to implement any of the above production processes, including:

[0020] A material preparation mechanism, comprising a material preparation cavity, a grab assembly installed in the material preparation cavity and used for transferring a material reaction frame, on which a reaction plate for containing reaction materials is arranged;

[0021] A reaction mechanism, comprising a reaction chamber connected to the lower part of the material preparation chamber, and a rotating disk installed at the bottom of the reaction chamber and used to place the material reaction frame, and an openable and closable material transfer airtight door is also provided between the reaction chamber and the material preparation chamber;

[0022] The condensation granulation mechanism comprises a condensation granulation chamber located beside the reaction chamber and connected thereto, and a nucleating agent tank body installed on the top of the condensation granulation chamber and used for installing nucleating agent materials, and a discharge pipe at the bottom of the nucleating agent tank body is connected to the condensation granulation chamber.

[0023] Furthermore, the grabbing assembly is a winch grab hook system arranged on the top of the material preparation chamber, which is used to hook the material reaction frame and transfer it between the material preparation chamber and the reaction chamber.

[0024] Furthermore, the reaction chamber is also provided with a rotating turntable in an inclined state. During the reaction, each group of material reaction frames is placed on the turntable at equal intervals along the circumference. Preferably, the inclination angle of the turntable is 5 to 15 degrees. In this way, when multiple groups of material reaction frames are placed on the turntable, the heavier material reaction frames are always located at the lower point. In this way, gravity screening of the reaction disk can be achieved, and there is no need to open the furnace to manually distinguish whether the material in the reaction disk has reacted. The specific process is: after a period of reaction, the material reaction frame with the most complete reaction disk rises to the highest point, at which time it can be taken out, and the material reaction frame with a new reaction disk is placed on the reaction disk. Because the new material reaction frame is equipped with more reaction materials and has a larger mass, it has a downward trend, causing the turntable to rotate, and the newly loaded material reaction frame drops to a relatively low point. At the same time, the lighter material frame with a relatively more complete reaction rotates to a high point with the turntable, which is convenient for the next removal. In this way, continuous production can be carried out without stopping the furnace. The design of the turntable is simple, the only wear part is the axis, and it uses high temperature resistant bearings or high temperature resistant lubricating materials for relative sliding.

[0025] Furthermore, a temperature-insulating chamber is provided between the reaction chamber and the material preparation chamber, the material transfer airtight door is provided between the temperature-insulating chamber and the material preparation chamber, and an openable and closable temperature-insulating door is provided between the temperature-insulating chamber and the reaction chamber.

[0026] Furthermore, the bottom discharge pipe of the nucleating agent tank body also extends into the condensation granulation cavity, a distribution net for uniform distribution is provided on the bottom discharge pipe, and a distribution vibrator is also provided on the bottom discharge pipe.

[0027] Furthermore, a discharge tank is also connected to the bottom of the condensation granulation chamber.

[0028] Furthermore, an openable and closable discharge airtight door is provided between the discharge tank and the condensation granulation chamber.

[0029] Furthermore, the material preparation chamber, reaction chamber, condensation granulation chamber, and nucleating agent tank are also respectively provided with independent vacuum and gas replacement mechanisms for controlling the internal air pressure.

[0030] Furthermore, a heating element is provided in the reaction chamber, and temperature control components are provided in the condensation granulation chamber and the nucleating agent tank body, respectively.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) The process is simple and highly operable. It can continuously produce high-performance silicon oxide powder by combining with a variety of condensation cores. The powder produced by various doped silicon oxide powders can be used as high-performance lithium-ion battery negative electrode materials.

[0033] (2) The production cost is low, the raw materials are simple, a variety of silicon sources and silica can be used, a variety of condensation cores can be used, and there are no special requirements for the core morphology.

[0034] (3) The process batch output is large, and the furnace temperature can be raised once for long-term production. It is environmentally friendly, the reaction environment is closed, and there is no water pollution and air pollution. The production environment is safe, the level of automation is high, and workers do not directly contact raw materials and products.

[0035] (4) The equipment has a simple structure and is easy to maintain. There is no precision and vulnerable machinery in the high-temperature area of ​​the equipment furnace. The entire equipment has no continuous wear components, and the finished product has high purity and no grinding chips.

[0036] (5) The reaction of silicon dioxide vapor can be carried out in a completely closed and vacuum or atmosphere environment without stopping the furnace for charging or replacing vulnerable parts, thereby improving production efficiency and reducing energy consumption;

[0037] (6) The produced silicon oxide or core-doped silicon oxide powder has initially solved the current difficulties in silicon oxide doping and pre-lithiation. The core-doped silicon oxide powder formed can be doped with various elements, including lithium metal, lithium metal oxide, lithium salt, etc., and pre-lithiation can be carried out simultaneously when preparing silicon oxide. Or when the condensed core is replaced by silicon dioxide or silicon oxide, silicon oxide powder with lower internal core stress is provided, thereby improving its cycle life as a negative electrode material for lithium-ion batteries. When the condensed core is replaced by pure silicon, silicon oxide-coated pure silicon powder will be provided. The above powders can be carbon-coated to become negative electrode materials for lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a cross-sectional schematic diagram of the production equipment of the present invention;

[0039] Figure 2 Schematic diagram of produced silicon oxide or core-doped silicon oxide powder;

[0040] Figure 3 It is a schematic diagram of the production equipment in Example 2;

[0041] Figure 4 The working diagram of the rotating disk in the reaction chamber (from left to right);

[0042] Figure 5 The first charge and discharge voltage curves of the core-doped silicon oxide prepared in Example 2 and commercially available silicon oxide;

[0043] Figure 6 This is a capacity cycle life diagram of the core doped silicon oxide prepared in Example 2 and commercial silicon oxide;

[0044] Description of the markings in the figure:

[0045] 1-material preparation chamber, 2-reaction chamber, 3-condensation granulation chamber, 4-entry and exit closed door, 5-winch grab hook system, 6-material transfer airtight door, 7-thermal insulation door, 8-material reaction frame, 9-turntable, 10-nucleating agent tank, 11-tank valve, 12-material distribution vibrator, 13-discharging airtight door, 14-discharging tank, 15-first vacuum and gas replacement mechanism, 16-second vacuum and gas replacement mechanism, 17-third vacuum and gas replacement mechanism, 18-fourth vacuum and gas replacement mechanism, 19-first thermometer, 20-second thermometer, 21-third thermometer, 22-fourth thermometer, 23-material distribution net, 24-heating element, 25-first temperature control resistor, 26-second temperature control resistor. DETAILED DESCRIPTION

[0046] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0047] In the following implementation manners or examples, unless otherwise specified, functional components or structures are conventional components or structures used in the art to achieve corresponding functions.

[0048] In order to realize efficient and continuous production and preparation of silicon oxide, especially core-doped silicon oxide powder, the present invention provides a production process for silicon oxide or core-doped silicon oxide powder, comprising the following steps:

[0049] (1) placing a reaction material for producing silicon oxide in a heating chamber and heating the reaction material to produce silicon oxide vapor;

[0050] (2) When the amount of silicon oxide vapor generated is sufficient, it overflows into the condensation granulation chamber, and at the same time, the nucleating agent is spread from above the silicon oxide vapor and falls by gravity;

[0051] (3) During the falling process of the nucleating agent, silicon oxide vapor condenses on the surface of the nucleating agent, and silicon oxide powder is formed with a silicon oxide shell covering the nucleating agent core.

[0052] In some specific embodiments, in step (1), the reaction material is silicon monoxide, or a silicon-containing material used for reacting to generate silicon monoxide vapor.

[0053] In some specific embodiments, in step (1), the heating temperature is 1000°C to 1500°C.

[0054] In some specific embodiments, in step (1), the vacuum degree in the heating chamber is maintained at 0.001 Pa to 100 Pa, so that the silicon source and the oxygen source can reach the conditions for disproportionation reaction and generate silicon dioxide vapor.

[0055] In some specific embodiments, in step (2), the temperature of the nucleating agent before spreading is controlled at -40°C to 1000°C in order to create a temperature difference between the nucleating agent and the silicon oxide vapor temperature. By controlling the temperature difference, the thickness of the coating layer can be controlled and the amount of doping elements in the coating layer can be controlled.

[0056] In some specific embodiments, in step (2), the nucleating agent is a metal, an alkali metal, a metal mixture, a metal oxide, a non-metal oxide or a nitride, etc. Furthermore, in step (2), the nucleating agent is silicon dioxide, silicon, silicon oxide, titanium dioxide, lithium metal, a lithium-containing compound or lithium oxide, etc. Specifically, when the nucleating agent is silicon oxide, the generated powder is pure silicon oxide powder, and when the nucleating agent is other condensation cores, it is silicon oxide powder with core doping.

[0057] In some specific embodiments, in step (2), the particle size of the nucleating agent is 0.1nm to 100μm, preferably 5nm to 5μm. By controlling the particle size, the thickness of the coating layer can be controlled, the oxygen content can be controlled when producing silicon oxide, and the ratio of the doping element to silicon oxide in the coating layer can be controlled when producing core-doped particles. The size of the condensation core is an important factor affecting the physical and chemical properties of the finished particles. The larger the size of the condensation core, the larger the size of the finished particles. The condensation core also affects the element ratio of the finished particles. For example: when silicon dioxide is used as the condensation core, the total oxygen content of the obtained finished particles is higher, and when pure silicon is used as the condensation core, the total oxygen content of the obtained finished particles is lower. When lithium oxide is used as the condensation core, the obtained finished particles have a certain total lithium content.

[0058] In addition, in order to implement the above production process, the present invention also provides a production device for silicon oxide or core-doped silicon oxide powder, the structure of which can be seen in Figure 1 As shown in the following, including:

[0059] The material preparation mechanism comprises a material preparation chamber 1, a grab assembly installed in the material preparation chamber 1 and used for transferring a material reaction frame 8, and a reaction plate for containing reaction materials is arranged on the material reaction frame 8;

[0060] The reaction mechanism comprises a reaction chamber 2 connected to the lower part of the material preparation chamber 1, and a rotary plate 9 installed at the bottom of the reaction chamber 2 and used to place the material reaction frame 8, and an openable and closable material transfer airtight door 6 is also provided between the reaction chamber 2 and the material preparation chamber 1;

[0061] The condensation granulation mechanism includes a condensation granulation chamber 3 located next to the reaction chamber 2 and connected thereto, and a nucleating agent tank body 10 installed on the top of the condensation granulation chamber 3 and used to install the nucleating agent material, and the discharge pipe at the bottom of the nucleating agent tank body 10 is connected to the condensation granulation chamber 3.

[0062] The main function of the material preparation chamber 1 in the present invention is to balance the atmosphere and pressure in the sample and the reaction chamber 2, so that the atmosphere and pressure in the reaction chamber 2 and the condensation granulation chamber 3 do not need to change during the production process.

[0063] In some specific embodiments, the grabbing assembly is a hoisting hook system 5 disposed on the top of the preparation chamber 1, which is used to hook the material reaction frame 8 and transfer it between the preparation chamber 1 and the reaction chamber 2. The hoisting hook system 5 here adopts a hoisting device that can realize the corresponding lifting and / or horizontal conveying functions in the field and is equipped with a grabber with a grabbing function. At the same time, the material reaction frame 8 can be made of cheap and high-temperature resistant materials, and the reaction tray can be replaced and used to load raw materials and waste. During operation, the reaction tray loaded with raw materials and the corresponding material reaction frame 8 are transferred to the reaction chamber 2 through the grabbing assembly, while the reaction tray and the corresponding material reaction frame 8 in the reaction chamber 2 that have completed the reaction and loaded with waste are transferred out of the reaction chamber 2.

[0064] In some specific embodiments, the reaction chamber 2 is also provided with a rotating disc 9 in an inclined state and can rotate. During the reaction, each group of material reaction frames 8 is placed on the rotating disc 9 at equal intervals along the circumferential direction. Preferably, the inclination angle of the rotating disc 9 is 5 to 15°. In this way, when multiple groups of material reaction frames 8 are placed on the rotating disc 9, the heavier material reaction frames 8 are always located at the lower point. In this way, gravity screening of the reaction disc can be achieved, and there is no need to manually distinguish whether the material in the reaction disc has reacted completely without opening the furnace. The specific process is: after a period of reaction, the material reaction frame 8 with the most complete reaction disc rises to the highest point, then it is taken out, and then the material reaction frame 8 with a new reaction disc is placed on the reaction disc. Since the new material reaction frame 8 is heavier, it will drop to the lower point. At the same time, the material disc with a relatively more complete reaction will rise to the highest point. In this way, continuous production can be carried out without stopping the furnace. The rotating disc 9 is simple in design, and the only wear part is the axial part. It can be relatively slidable with high-temperature resistant bearings or directly with high-temperature resistant materials.

[0065] When the reaction materials are placed in the reaction disk on the turntable 9, due to gravity and the weight of the raw materials, the reaction disk will rotate to a position with a lower center of gravity. The reaction disk that has completed the reaction or has been reacting for a period of time is lighter and will rotate to a higher position, realizing the screening of the reaction disk without mechanical devices, thereby reducing the active equipment and increasing the service life. When necessary, there is also an external rotating device for manual selection.

[0066] In some specific embodiments, a temperature-isolating chamber is further provided between the reaction chamber 2 and the material preparation chamber 1 , the material transfer airtight door 6 is provided between the temperature-isolating chamber and the material preparation chamber 1 , and an openable and closable temperature-isolating door 7 is provided between the temperature-isolating chamber and the reaction chamber 2 .

[0067] In some specific embodiments, the bottom discharge pipe of the nucleating agent tank body 10 also extends into the condensation granulation chamber 3, and a distribution net 23 for uniform spreading is provided on the bottom discharge pipe, and a distribution vibrator 12 is also provided on the bottom discharge pipe.

[0068] In some specific embodiments, a discharge tank 14 is also connected to the bottom of the condensation granulation chamber 3. Furthermore, an openable and closable discharge airtight door 13 is also provided between the discharge tank 14 and the condensation granulation chamber 3. An independent vacuum and gas replacement mechanism for controlling the internal air pressure of the discharge tank 14 is also provided.

[0069] In some specific embodiments, the preparation chamber 1, the reaction chamber 2, the condensation granulation chamber 3, and the nucleating agent tank body 10 are also provided with independent vacuum and gas replacement mechanisms for controlling the internal air pressure. It should be pointed out here that the vacuum and gas replacement mechanism is a common pipeline valve structure commonly used in the art that can adjust the pressure and atmosphere in the chamber by vacuum pumping or inflation. In this way, during the specific work, the air pressure in the reaction chamber 2 and other chambers can be pumped to a set negative pressure or the internal atmosphere can be replaced with a desired atmosphere such as argon or nitrogen. At the same time, the remaining chambers can control the air pressure balance to achieve the smooth progress of the entire working process.

[0070] In some specific embodiments, a heating element 24 is further provided in the reaction chamber 2, and a temperature control component is also provided at the condensation granulation chamber 3 and the nucleating agent tank 10. Through the heating element 24 (which can be selected as a heating resistor) and the temperature control component (which can be selected as a first temperature control resistor 25 and a second temperature control resistor 26, respectively), the specific temperature required for heating or temperature control can be coordinated with the second thermometer 20, the third thermometer 21, the fourth thermometer 22, etc. provided in a matching manner to realize the corresponding temperature control function.

[0071] In some specific embodiments, when the production device of the present invention is used, the production method is specifically as follows:

[0072] (1) placing a reaction plate containing reaction materials on a material reaction frame 8, and then hanging the material reaction frame 8 on the grabbing assembly;

[0073] (2) Open the passage between the material preparation chamber 1 and the reaction chamber 2, and place the material reaction frame 8 on the rotating disk 9 in the reaction chamber 2 by the grabbing assembly, and then return the grabbing assembly to the material preparation chamber 1, close the material transfer airtight door 6, and then adjust the air pressure or atmosphere in the reaction chamber 2 to the required requirements, and then heat the reaction chamber 2, so that the reaction materials on the reaction disk react to generate silicon dioxide gas;

[0074] (3) When the reaction time meets the requirements, the silicon oxide gas generated in the reaction chamber 2 overflows into the condensation granulation chamber 3. At this time, the bottom discharge tank 14 of the nucleating agent tank body 10 is opened to allow the nucleating agent to be spread into the condensation granulation chamber 3. At this time, the hotter silicon oxide gas will condense on the colder nucleating agent and cool down during the falling process, eventually forming silicon oxide or core-doped silicon oxide powder.

[0075] More specifically, the process of the production method of the present invention is specifically as follows:

[0076] For the first feeding, the reaction materials (such as silicon-containing materials or silicon dioxide and pure silicon and silicon monoxide, etc.) are first loaded into the reaction tray, and then the material reaction frame 8 loaded with the reaction tray is hung into the material preparation chamber 1. At this time, the number of loaded reaction trays is not limited.

[0077] After the tank valve 11 is closed, the corresponding nucleating agent is loaded into the nucleating agent tank 10, and the gas pressure or atmosphere in the nucleating agent tank 10 is controlled to the required requirements. The loaded material reaction frame 8 is placed on the turntable 9 in the reaction chamber 2 through the opened material transfer airtight door 6 and the thermal insulation door 7 between the preparation chamber 1 and the reaction chamber 2 using the winch grab system 5. At this time, the material transfer airtight door 6 and the thermal insulation door 7 are closed, so that the reaction chamber 2 and the condensation granulation chamber 3 become airtight spaces at the same time, and the first vacuum and gas replacement mechanism 15 is used to evacuate to the required pressure or replace with the required gas. In this step, the discharge airtight door 13, the material transfer airtight door 6, and the tank valve 11 are all closed, and the thermal insulation door 7 is closed. After reaching the required air pressure or atmosphere requirements, the heating element 24 is turned on, and the first thermometer 19 is cooperated to heat to the required temperature. At this time, the temperature is controlled below the suitable condensation temperature for spreading by cooperating with the first thermometer 19, the second thermometer 20, the third thermometer 21, the fourth thermometer 22, the heating element 24, the first temperature control resistor 25, and the second temperature control resistor 26. The specific temperature is determined by the nucleating agent to be spread and the product requirements.

[0078] When the time is met, the silicon oxide gas in the reaction chamber 2 overflows, and the tank valve 11 and the distribution vibrator 12 are opened to evenly spread the nucleating agent in the condensation granulation chamber 3 through the distribution net 23. The temperature-controlled nucleating agent is relatively cold, so that the hot silicon oxide gas overflowing from the reaction chamber 2 condenses on the nucleating agent. As it falls and cools down in the condensation granulation chamber 3, silicon oxide powder is finally formed and falls on the discharge airtight door 13 inside the condensation granulation chamber 3. After a certain time, the fourth vacuum and gas replacement mechanism 18 is used to evacuate the discharge tank 14 to the required pressure or replace it with the required gas. Make the discharge tank 14 and the condensation granulation chamber 3 have the same air pressure and atmosphere, open the discharge airtight door 13, and the material falls into the discharge tank 14. After the discharge is completed, the discharge airtight door 13 is closed. The fourth vacuum and gas replacement mechanism 18 is used to balance the discharge tank 14 with the external air pressure. After cooling to a certain temperature, the discharge tank 14 can be removed from the discharge airtight door 13 to complete one discharge.

[0079] To use the equipment continuously, the material needs to be loaded into the material reaction frame 8 and the frame is hung in the material preparation chamber 1, the inlet and outlet closed door 4 is closed, the gas pressure or atmosphere in the material preparation chamber 1 is controlled to the required requirements by the fourth vacuum and gas replacement mechanism 18, the material transfer airtight door 6 and the temperature insulation door 7 are opened in conjunction, and the material reaction frame 8 and the frame that have been reacted are taken out by the hoisting and grabbing hook system 5 and hung in the material preparation chamber 1. The hoisting and grabbing hook system 5 is used to put the loaded material reaction frame 8 and the frame through the opened material transfer airtight door 6 and the temperature insulation door 7 onto the turntable 9 in the reaction chamber 2.

[0080] Close the transfer airtight door 6 and the insulation door 7. Use the second vacuum and gas replacement mechanism 16 to balance the material preparation chamber 1 with the external air pressure, and then open the entry and exit closed door 4 to carry out material reaction frame 8 and material replacement. After the connection between the nucleating agent tank body 10 and the warehouse door and the condensation granulation chamber 3 is closed by the tank body valve 11, the third vacuum and gas replacement mechanism 17 is used to balance with the external atmospheric pressure, and the nucleating agent tank body 10 is opened to replenish the nucleating agent. Then the third vacuum and gas replacement mechanism 17 is used to balance with the gas atmosphere in the condensation granulation chamber 3 to carry out production. Material collection is the same as the first production.

[0081] The above embodiments may be implemented individually or in any combination of two or more.

[0082] The above implementation is described in more detail below in conjunction with specific examples.

[0083] Embodiment 1:

[0084] In order to achieve efficient and continuous production and preparation of silicon oxide, especially core-doped silicon oxide powder, the present embodiment provides a production process for silicon oxide or core-doped silicon oxide powder, including the following steps:

[0085] (1) placing a reaction material for producing silicon oxide in a heating chamber and heating the reaction material to produce silicon oxide vapor;

[0086] (2) When the amount of silicon oxide vapor generated is sufficient, it overflows into the condensation granulation chamber, and at the same time, the nucleating agent is spread from above the silicon oxide vapor and falls by gravity;

[0087] (3) During the falling process of the nucleating agent, silicon oxide vapor condenses on the surface of the nucleating agent, and silicon oxide powder is formed with a silicon oxide shell covering the nucleating agent core.

[0088] In the above production process, the reaction material is silicon oxide, or silicon-containing materials (such as silicon source or silicon oxygen source) used for reacting to generate silicon oxide vapor. Specifically, the silicon source may be pure silicon, metallic silicon, cutting silicon powder, silicon mud, and the silicon oxygen source may be silicon dioxide, glass slag, silica ore, quartz sand, silicon oxide production waste.

[0089] In addition, in order to generate silicon dioxide vapor, in step (1), the heating temperature is 1000° C. to 1500° C., and the vacuum degree in the heating chamber is maintained at 0.001 Pa to 100 Pa, and in this embodiment, 0.05 Pa is selected.

[0090] In step (2), the temperature of the nucleating agent before spreading is controlled at -40°C to 1000°C. In this embodiment, the temperature is controlled at room temperature.

[0091] At the same time, in step (2), the nucleating agent is a metal, an alkali metal, a metal mixture, a metal oxide, a non-metallic oxide or a nitride, etc. For example, the nucleating agent is silicon dioxide, silicon, silicon oxide, lithium metal, a lithium-containing compound or lithium oxide, etc. Specifically, when the nucleating agent is silicon oxide, the generated powder is pure silicon oxide powder, and when the nucleating agent is other condensed cores, it is silicon oxide powder with core doping. In addition, in step (2), the particle size of the nucleating agent is 0.1nm to 100μm, and the particle size of the present embodiment is selected to be about 100nm.

[0092] The silicon dioxide powder prepared by the production process of this embodiment is as follows Figure 2 As shown, the number of condensation cores in the powder can be one or more.

[0093] Embodiment 2:

[0094] In order to realize efficient and continuous production and preparation of silicon oxide, especially core-doped silicon oxide powder, this embodiment provides a production device for silicon oxide or core-doped silicon oxide powder on the basis of the above-mentioned embodiment 1. The structure of the device can be seen in Figure 1 As shown in the following, including:

[0095] The material preparation mechanism comprises a material preparation chamber 1, a grab assembly installed in the material preparation chamber 1 and used for transferring a material reaction frame 8, and a reaction plate for containing reaction materials is arranged on the material reaction frame 8;

[0096] The reaction mechanism comprises a reaction chamber 2 connected to the lower part of the material preparation chamber 1, and a rotary plate 9 installed at the bottom of the reaction chamber 2 and used to place the material reaction frame 8, and an openable and closable material transfer airtight door 6 is also provided between the reaction chamber 2 and the material preparation chamber 1;

[0097] The condensation granulation mechanism includes a condensation granulation chamber 3 located next to the reaction chamber 2 and connected thereto, and a nucleating agent tank body 10 installed on the top of the condensation granulation chamber 3 and used to install the nucleating agent material, and the discharge pipe at the bottom of the nucleating agent tank body 10 is connected to the condensation granulation chamber 3.

[0098] In this embodiment, the main function of the material preparation chamber 1 is to balance the atmosphere and pressure in the sample and the reaction chamber 2, so that the atmosphere and pressure in the reaction chamber 2 and the condensation granulation chamber 3 do not need to change during the production process.

[0099] The grabbing assembly is a hoisting hook system 5 arranged on the top of the preparation chamber 1, which is used to hook the material reaction frame 8 and transfer it between the preparation chamber 1 and the reaction chamber 2. The hoisting hook system 5 here adopts a hoisting device that can realize the corresponding lifting and / or horizontal conveying functions in the field and is equipped with a grabber with a grabbing function. At the same time, the material reaction frame 8 can be made of cheap and high-temperature resistant materials, and the reaction disk can be replaced and used to load raw materials and waste. During operation, the reaction disk loaded with raw materials and the corresponding material reaction frame 8 are transferred to the reaction chamber 2 through the grabbing assembly, while the reaction disk and the corresponding material reaction frame 8 in the reaction chamber 2 that have completed the reaction and loaded with waste are transferred out of the reaction chamber 2.

[0100] The reaction chamber 2 is also provided with a rotating disc 9 in an inclined state and can rotate. During the reaction, each group of material reaction frames 8 are placed on the rotating disc 9 at equal intervals along the circumferential direction. Preferably, the inclination angle of the rotating disc 9 is 5 to 15°. In this way, when multiple groups of material reaction frames 8 are placed on the rotating disc 9, the heavier material reaction frames 8 are always located at the lower point. In this way, gravity screening of the reaction disc can be achieved, and there is no need to manually distinguish whether the material in the reaction disc has reacted completely without opening the furnace. The specific process is: after a period of reaction, the material reaction frame 8 with the most complete reaction disc rises to the highest point, then it is taken out, and then the material reaction frame 8 with a new reaction disc is placed on the reaction disc. Since the new material reaction frame 8 is heavier, it will drop to the lower point. At the same time, the material disc with a relatively more complete reaction will rise to the highest point. In this way, continuous production can be carried out without stopping the furnace. The rotating disc 9 is simple in design, and the only wear part is the axial part. It can be relatively slidable with high-temperature resistant bearings or directly with high-temperature resistant materials. When the reaction materials are placed in the reaction disk on the turntable 9, due to gravity and the weight of the raw materials, the reaction disk will rotate to a position with a lower center of gravity. The reaction disk that has completed the reaction or has been reacting for a period of time is lighter and will rotate to a higher position, realizing the screening of the reaction disk without mechanical devices, thereby reducing the active equipment and increasing the service life. When necessary, there is also an external rotating device for manual selection.

[0101] A temperature-insulating chamber is further provided between the reaction chamber 2 and the material preparation chamber 1 , the material transfer airtight door 6 is provided between the temperature-insulating chamber and the material preparation chamber 1 , and an openable and closable temperature-insulating door 7 is provided between the temperature-insulating chamber and the reaction chamber 2 .

[0102] The bottom discharge pipe of the nucleating agent tank body 10 also extends into the condensation granulation chamber 3, and a distribution net 23 for uniform distribution is provided on the bottom discharge pipe, and a distribution vibrator 12 is also provided on the bottom discharge pipe.

[0103] The bottom of the condensation granulation chamber 3 is also connected to a discharge tank 14. Furthermore, an openable and closable discharge airtight door 13 is provided between the discharge tank 14 and the condensation granulation chamber 3. The discharge tank 14 is also provided with an independent vacuum and gas replacement mechanism for controlling the internal air pressure thereof.

[0104] The preparation chamber 1, reaction chamber 2, condensation granulation chamber 3, and nucleating agent tank 10 are also respectively provided with independent vacuum and gas replacement mechanisms for controlling the internal air pressure. It should be pointed out here that the vacuum and gas replacement mechanism is a common pipeline valve structure commonly used in the art that can adjust the pressure and atmosphere in the chamber through actions such as vacuum pumping or inflation. In this way, during specific work, the air pressure in the reaction chamber 2 and other chambers can be pumped to a set negative pressure or the internal atmosphere can be replaced with a desired atmosphere such as argon or nitrogen. At the same time, the remaining chambers can control the air pressure balance to achieve the smooth progress of the entire working process.

[0105] A heating element 24 is also provided in the reaction chamber 2, and a temperature control component is also provided at the condensation granulation chamber 3 and the nucleating agent tank 10. Through the heating element 24 (which can be selected as a heating resistor) and the temperature control component (which can be selected as a first temperature control resistor 25 and a second temperature control resistor 26), the specific temperature required for heating or temperature control can be coordinated with the second thermometer 20, the third thermometer 21, the fourth thermometer 22, etc. to achieve the corresponding temperature control function.

[0106] Based on the above production equipment, the production method of silicon oxide or core-doped silicon oxide powder in this embodiment is specifically as follows:

[0107] For the first feeding, the reaction materials (such as silicon-containing materials or silicon dioxide and pure silicon and silicon monoxide, etc.) are first loaded into the reaction tray, and then the material reaction frame 8 loaded with the reaction tray is hung into the material preparation chamber 1. At this time, the number of loaded reaction trays is not limited.

[0108] After the tank valve 11 is closed, the corresponding nucleating agent is loaded into the nucleating agent tank 10, and the gas pressure or atmosphere in the nucleating agent tank 10 is controlled to the required requirements. The loaded material reaction frame 8 is placed on the turntable 9 in the reaction chamber 2 through the opened material transfer airtight door 6 and the thermal insulation door 7 between the preparation chamber 1 and the reaction chamber 2 using the winch grab system 5. At this time, the material transfer airtight door 6 and the thermal insulation door 7 are closed, so that the reaction chamber 2 and the condensation granulation chamber 3 become airtight spaces at the same time, and the first vacuum and gas replacement mechanism 15 is used to evacuate to the required pressure or replace with the required gas. In this step, the discharge airtight door 13, the material transfer airtight door 6, and the tank valve 11 are all closed, and the thermal insulation door 7 is closed. After reaching the required air pressure or atmosphere requirements, the heating element 24 is turned on, and the first thermometer 19 is cooperated to heat to the required temperature. At this time, the temperature is controlled below the suitable condensation temperature for spreading by cooperating with the first thermometer 19, the second thermometer 20, the third thermometer 21, the fourth thermometer 22, the heating element 24, the first temperature control resistor 25, and the second temperature control resistor 26. The specific temperature is determined by the nucleating agent to be spread and the product requirements.

[0109] When the time is met, the silicon oxide gas in the reaction chamber 2 overflows, and the tank valve 11 and the distribution vibrator 12 are opened to evenly spread the nucleating agent in the condensation granulation chamber 3 through the distribution net 23. The temperature-controlled nucleating agent is relatively cold, so that the hot silicon oxide gas overflowing from the reaction chamber 2 condenses on the nucleating agent. As it falls and cools down in the condensation granulation chamber 3, silicon oxide powder is finally formed and falls on the discharge airtight door 13 inside the condensation granulation chamber 3. After a certain time, the fourth vacuum and gas replacement mechanism 18 is used to evacuate the discharge tank 14 to the required pressure or replace it with the required gas. Make the discharge tank 14 and the condensation granulation chamber 3 have the same air pressure and atmosphere, open the discharge airtight door 13, and the material falls into the discharge tank 14. After the discharge is completed, the discharge airtight door 13 is closed. The fourth vacuum and gas replacement mechanism 18 is used to balance the discharge tank 14 with the external air pressure. After cooling to a certain temperature, the discharge tank 14 can be removed from the discharge airtight door 13 to complete one discharge.

[0110] To use the equipment continuously, the material needs to be loaded into the material reaction frame 8 and the frame is hung in the material preparation chamber 1, the inlet and outlet closed door 4 is closed, the gas pressure or atmosphere in the material preparation chamber 1 is controlled to the required requirements by the fourth vacuum and gas replacement mechanism 18, the material transfer airtight door 6 and the temperature insulation door 7 are opened in conjunction, and the material reaction frame 8 and the frame that have been reacted are taken out by the hoisting and grabbing hook system 5 and hung in the material preparation chamber 1. The hoisting and grabbing hook system 5 is used to put the loaded material reaction frame 8 and the frame through the opened material transfer airtight door 6 and the temperature insulation door 7 onto the turntable 9 in the reaction chamber 2.

[0111] Close the transfer airtight door 6 and the insulation door 7. Use the second vacuum and gas replacement mechanism 16 to balance the material preparation chamber 1 with the external air pressure, and then open the entry and exit closed door 4 to carry out material reaction frame 8 and material replacement. After the connection between the nucleating agent tank body 10 and the warehouse door and the condensation granulation chamber 3 is closed by the tank body valve 11, the third vacuum and gas replacement mechanism 17 is used to balance with the external atmospheric pressure, and the nucleating agent tank body 10 is opened to replenish the nucleating agent. Then the third vacuum and gas replacement mechanism 17 is used to balance with the gas atmosphere in the condensation granulation chamber 3 to carry out production. Material collection is the same as the first production.

[0112] Embodiment 3:

[0113] Based on the production equipment and process provided in Example 2, the process of producing the core-doped silicon dioxide powder in this example is as follows:

[0114] The reaction raw materials used in this embodiment are high-purity metallic silicon and high-purity silicon dioxide, satisfying the molar ratio of oxygen to silicon element of 1:1. They are evenly mixed and spread in the reaction tray, and the thickness of the spread raw materials is about 4 cm. Ten layers of trays are placed in each material reaction frame 8, and then the material reaction frame 8 is hoisted into the reaction chamber 2. Specifically, six sets of material reaction frames 8 are first placed in the reaction chamber 2, and then each airtight door is closed, and the air pressure of the reaction chamber 2 and the condensation granulation chamber 3 is controlled at about 0.001 Pa through the corresponding vacuum and gas replacement mechanism, and the temperature in the reaction chamber 2 is controlled at about 1300°C. At the same time, the temperature of the condensation point (i.e., the position where the silicon dioxide gas just overflows into the condensation granulation chamber 3) is controlled at about 1100°C. A sufficient amount of nucleating agent lithium hydroxide is added to the nucleating agent tank 10, and its temperature is controlled at about 150°C, the size is controlled to be about 50nm, and the aperture of the cloth net 23 is designed to be 200nm~1μm. The cloth vibrator 12 is turned on to make the lithium hydroxide nucleating agent in the cloth net 23 fall from above. When passing through the supercooled silicon oxide vapor, due to the large temperature difference and the phase transition point of lithium hydroxide being much lower than silicon oxide, silicon oxide rapidly condenses on the surface of lithium hydroxide to form a completely wrapped silicon oxide core doped lithium hydroxide powder. The specific morphology can be seen in Figure 2 shown.

[0115] A button half-cell was used for testing. The core doped silicon oxide in this embodiment was coated with gas phase carbon and then mixed with conductive carbon black and sodium carboxymethyl cellulose at a mass ratio of 88:6:6 to form a button cell. The first charge and discharge voltage curve was obtained from the test. Figure 5 , the dotted line is core-doped silicon oxide, and the solid line is commercially available silicon oxide using the same vapor phase carbon coating process.

[0116] contrast Figure 5 Using commercial silicon oxide coated with carbon under the same process conditions, it can be clearly seen that the specific capacity and first coulombic efficiency (1861 mAh / g, 91%) of the core-doped silicon oxide in Example 2 are higher than those of commercial silicon oxide (1390 mAh / g, 75%).

[0117] The core doped silicon oxide carbon coated precursor (accounting for 15%) of the present invention is compounded with graphite to form a core doped silicon oxide and graphite composite. Then the composite: conductive carbon black: sodium carboxymethyl cellulose = 88:6:6 is used for slurrying and preparing the negative electrode. The test results are shown in Table 1. The capacity retention rate after 100 weeks at a rate of 0.5C is 90%, while the capacity retention rate of commercially available silicon oxide as a control is only 83% (see Table 1). Figure 6 ).

[0118] Table 1

[0119]

[0120]

[0121] Embodiment 4:

[0122] On the basis of Example 3, the nucleating agent is replaced with titanium dioxide, and the temperature of the nucleating agent is controlled to be between 0 and 100° C. The water content of titanium dioxide is controlled to be between 0.1% and 10%. Finally, titanium dioxide powder doped with silicon dioxide core is obtained.

[0123] Embodiment 5:

[0124] On the basis of Example 3, the nucleating agent is replaced with silicon dioxide, and the temperature of the nucleating agent is controlled to between 0 and 500° C. Finally, silicon dioxide powder doped with silicon dioxide core is obtained.

[0125] Example 6

[0126] On the basis of Example 3, the nucleating agent is replaced with the silicon oxide core doped silica powder produced in Example 3, and the molar ratio of silicon and oxygen in the raw material is changed to 5:1 to 1:5. Finally, the silicon oxide core doped silica powder with high silicon or high oxygen coating is obtained.

[0127] Embodiment 7:

[0128] like Figure 3 Compared with Example 1, most of them are the same, except that the material reaction frame 8 is no longer hoisted in from above but pushed in from the side, and the lighter pallets after the reaction are taken out by the take-out machine. The new pallet frame is put in from the side. The electrical equipment is kept cool by circulating water cooling.

[0129] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for producing silicon oxide or core-doped silicon oxide powder, characterized in that: The following steps are involved: (1) placing a reaction material for producing silicon oxide in a heating chamber and heating the reaction material to produce silicon oxide vapor; (2) When the amount of silicon oxide vapor generated is sufficient, it overflows into the condensation granulation chamber, and at the same time, the nucleating agent is spread from above the silicon oxide vapor and falls by gravity; (3) During the falling process of the nucleating agent, silicon oxide vapor condenses on the surface of the nucleating agent, and silicon oxide powder is formed with a silicon oxide shell covering the nucleating agent core.

2. The method for producing silicon oxide or core-doped silicon oxide powder according to claim 1, characterized in that: In step (1), the reaction material is silicon monoxide, or a silicon-containing material used for reacting to generate silicon monoxide vapor.

3. The method for producing silicon oxide or core-doped silicon oxide powder according to claim 1, characterized in that: In step (1), the heating temperature is 1000°C to 1500°C.

4. The method for producing silicon oxide or core-doped silicon oxide powder according to claim 1, characterized in that: In step (1), the vacuum degree in the heating chamber is maintained at 0.001Pa to 100Pa.

5. The method for producing silicon oxide or core-doped silicon oxide powder according to claim 1, characterized in that: In step (2), the temperature of the nucleating agent before spreading is controlled at -40°C to 1000°C.

6. The method for producing silicon oxide or core-doped silicon oxide powder according to claim 1, characterized in that: In step (2), the nucleating agent is a metal, a metal mixture, a metal oxide, a non-metal oxide or a nitride.

7. The method for producing silicon oxide or core-doped silicon oxide powder according to claim 6, characterized in that: In step (2), the nucleating agent is silicon dioxide, silicon, silicon monoxide, lithium metal, titanium dioxide or a lithium-containing compound.

8. The method for producing silicon oxide or core-doped silicon oxide powder according to claim 1, characterized in that: In step (2), the particle size of the nucleating agent is 0.1 nm to 100 μm.

9. A production device for silicon oxide or core-doped silicon oxide powder, which is used to implement the production process according to any one of claims 1 to 8, characterized in that: The production unit includes: A material preparation mechanism, comprising a material preparation cavity, a grab assembly installed in the material preparation cavity and used for transferring a material reaction frame, on which a reaction plate for containing reaction materials is arranged; A reaction mechanism, comprising a reaction chamber connected to the lower part of the material preparation chamber, and a rotating disk installed at the bottom of the reaction chamber and used to place the material reaction frame, and an openable and closable material transfer airtight door is also provided between the reaction chamber and the material preparation chamber; The condensation granulation mechanism comprises a condensation granulation chamber located beside the reaction chamber and connected thereto, and a nucleating agent tank body installed on the top of the condensation granulation chamber and used for installing nucleating agent materials, and a discharge pipe at the bottom of the nucleating agent tank body is connected to the condensation granulation chamber.

10. The device for producing silicon oxide or core-doped silicon oxide powder according to claim 9, characterized in that: A temperature-insulating chamber is further provided between the reaction chamber and the material preparation chamber, the material transfer airtight door is provided between the temperature-insulating chamber and the material preparation chamber, and an openable and closable temperature-insulating door is provided between the temperature-insulating chamber and the reaction chamber; The bottom discharge pipe of the nucleating agent tank body also extends into the condensation granulation chamber, and a distribution net for uniform distribution is provided on the bottom discharge pipe, and a distribution vibrator is also provided on the bottom discharge pipe; A discharge tank is also connected to the bottom of the condensation granulation chamber, and an openable and closable discharge airtight door is also provided between the discharge tank and the condensation granulation chamber.

Images