CN116544401A - A kind of silicon anode material and its production system, production method and application - Google Patents

Abstract

The invention provides a silicon negative electrode material and a production system, a production method and application thereof, wherein the production system sequentially comprises a silicon oxide reaction generation unit, a fluidization crushing unit and a fluidization coating unit, and respectively realizes high-temperature vacuum evaporation, fluidization jet milling and fluidized bed chemical deposition, namely, the silicon oxide raw material is subjected to vacuum evaporation process to prepare massive silicon oxide, and is subjected to fluidization jet milling and screening, and then is subjected to gas phase carbon coating treatment in a fluidization state, so that the high-performance silicon negative electrode material is produced.

Description

A kind of silicon anode material and its production system, production method and application

technical field

The invention belongs to the field of electrode material manufacturing, and relates to a silicon negative electrode material and its production system, production method and application.

Background technique

With the rapid development of consumer electronics and electric vehicles, lithium-ion battery technology has been greatly developed. High specific energy lithium-ion batteries are the focus of development, and the key material that determines the energy density in lithium-ion batteries is the negative electrode material.

At present, commercial anode materials are mainly artificial/natural graphite. Among them, the theoretical specific capacity of graphite is 372mAh/g, which cannot meet the needs of high energy density batteries. The researchers found that the theoretical specific capacity of the silicon negative electrode is about 4200mAh/g, which is more than 10 times that of the graphite negative electrode, and there is no hidden danger of lithium precipitation, so its safety is better than that of graphite-based negative electrode materials, and it has the advantages of abundant reserves and low cost. , is the most potential next-generation lithium battery anode material.

However, silicon has a huge volume change during charge and discharge, and its electronic conductivity is extremely poor, which seriously affects the cycle performance and high current charge and discharge capability of silicon-based anodes. Silicon oxide-based composite materials are new anode materials that have attracted much attention in recent years. The inactive phases Li ₂ O and Li ₄ SiO ₄ formed during the first lithium intercalation process of silicon oxide-based negative electrode materials can prevent the agglomeration of nano-Si particles in the active phase, and can also effectively buffer the volume effect of Si during charge and discharge, and obtain Good cycle performance. Therefore, silicon oxide-based composite electrode materials have received extensive attention and development.

The prior art (International Journal of Electrochemical Science 7(2012): 8745) uses high-energy ball milling pretreatment to perform high-speed grinding treatment on commercial silicon oxide particles with a size of tens of microns, and the processed silicon oxide nanoparticles are combined with graphite to prepare oxide Silicon-based composite material, the cycle capacity of the material is still nearly 900mAh/g after 100 cycles. There is also an existing technology (Journal of Power Sources 222(2013): 129) that conducts high-temperature disproportionation and high-energy ball milling treatment on commercial nano-silica powder to prepare a silica-based negative electrode material, which still maintains a reversible capacity of 1000mAh/g after a long cycle. capacity.

Throughout the existing research reports on silicon oxide-based negative electrode materials, most of them use expensive commercial nano-silicon oxide as raw materials; in addition, nano-silicon oxide-based composite materials are prepared by high-energy ball milling, but the yield is low and the cost is high. The nanonization of materials results in lower tap density, which is not conducive to the requirement of high volume energy density of lithium-ion batteries for portable electronic devices. Considering that coating modification on the basis of silicon oxide is often concerned in process research, and from the perspective of industrialization, there is no report on a standardized coating process for silicon oxide negative electrodes.

In view of the deficiencies of the existing technologies, it is of great significance and urgency to develop a system and method for silicon anode materials with strong practicability, excellent material performance, continuous production and low cost.

Contents of the invention

In view of the problems existing in the prior art, the purpose of the present invention is to provide a silicon negative electrode material and its production system, production method and application. The production system sequentially includes a silicon oxide reaction generation unit, a fluidized crushing unit and a fluidized The coating unit realizes high-temperature vacuum evaporation, fluidized airflow pulverization and fluidized bed chemical deposition respectively, that is, the raw material of silicon oxide is prepared by vacuum evaporation process to prepare bulk silicon oxide, and it is pulverized and screened by fluidized airflow Finally, gas-phase carbon coating treatment is carried out in a fluidized state to produce high-performance silicon negative electrode materials, forming a process system solution for silicon oxide negative electrode materials, which has the characteristics of systematic equipment, high yield, and continuous operation , the production method carried out by using the production system is simple in process, strong in operability, safe and reliable.

In a first aspect, the present invention provides a method. A production system for silicon negative electrode materials, the production system sequentially includes a silicon oxide reaction generation unit, a fluidized crushing unit, and a fluidized coating unit along the flow direction of materials;

The silicon oxide reaction generation unit includes a vacuum reaction chamber and a deposition reaction chamber connected in sequence, and the temperature of the vacuum reaction chamber is higher than the temperature of the deposition reaction chamber;

Both the fluidized crushing unit and the fluidized coating unit include an independently used fluidized bed device for performing airflow crushing and gas phase coating respectively, wherein the fluidized bed device of the fluidized coating unit includes a fluidized The bed encases the reaction chamber.

The design and structure of the production system in the present invention take into account the connection and matching between the various process sections, which can better realize the transmission of materials between the process sections, improve process efficiency, reduce material loss, and prolong the service life of each process section equipment. Use time, reduce the life cycle cost of the whole cycle.

It should be emphasized that the fluidized bed-coated reaction chamber has the following advantages: (1) the gas and solid are fully mixed, and the heat and mass transfer coefficient between the two phases is high, which can shorten the time and improve the production capacity of the equipment; (2) the equipment production It has high strength and can be operated continuously; (3) solid particles have fluid characteristics after fluidization, so it is convenient to operate, easy to control, and can reduce a certain amount of labor intensity; (4) simple equipment, easy to maintain and manufacture; (5) operation Good security.

The fluidized bed coating reaction chamber of the present invention is preferably a vertical fluidized bed reactor, and the fluidized bed chemical vapor deposition method is used to complete the carbon coating in it, so that high-performance silicon negative electrode materials can be continuously produced, and at the same time shorten the Production cycle; the fluidized bed chemical vapor deposition method has high heat and mass transfer characteristics, which is conducive to improving reaction efficiency and sufficient reaction, so that gas molecules diffuse into the pores, defects and cracks of raw material particles, thereby depositing and forming effective landfill bags overlay structure.

The production system refers to an equipment system, a device system or a production device.

The following are preferred technical solutions of the present invention, but not as limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

As a preferred technical solution of the present invention, the vacuum reaction chamber is heated by a first heating furnace.

Preferably, the silicon oxide reaction production unit further includes a silo, and an outlet of the silo is connected to the vacuum reaction chamber.

Preferably, the silo is connected to the vacuum reaction chamber through a first valve.

Preferably, the deposition reaction chamber is heated by a second heating furnace.

Preferably, the discharge port of the vacuum reaction chamber is connected to the feed port of the deposition reaction chamber through a conveying device, and the discharge port of the deposition reaction chamber is the discharge port of the silicon oxide reaction generation unit.

As a preferred technical solution of the present invention, the fluidized bed device of the fluidized crushing unit is a fluidized bed airflow crushing device, and the inlet of the fluidized bed airflow crushing device is connected with the outlet of the silicon oxide reaction generation unit. The feed port is connected.

Preferably, the feed port of the fluidized-bed jet pulverization device is connected with the discharge port of the silicon oxide reaction generation unit through a second valve.

Preferably, the fluidized crushing unit further includes a powder screening device.

Preferably, the discharge port of the fluidized bed jet milling device is connected to the feed port of the powder screening device.

Preferably, the discharge port of the powder screening device is divided into two paths, one of which is returned to the feed port of the fluidized bed jet crushing device, and the other path is used as the discharge port of the fluidized crushing unit.

As a preferred technical solution of the present invention, the fluidized bed device of the fluidized coating unit further includes a third heating furnace for heating the fluidized bed coated reaction chamber, and the feed of the fluidized bed coated reaction chamber is The port is connected with the discharge port of the fluidized crushing unit.

Preferably, the feed port of the fluidized bed coating reaction chamber is connected with the discharge port of the fluidized crushing unit through a third valve.

The first valve, the second valve and the third valve in the present invention are all flow control valves, which are used to control the flow direction of materials.

Preferably, the fluidized bed coating reaction chamber is provided with a fluidization gas inlet, a coating gas inlet, a tail gas outlet and a product outlet.

Preferably, both the fluidization gas inlet and the coating gas inlet are independently arranged at the bottom of the fluidized bed coating reaction chamber, and are respectively connected with a fluidization gas inlet pipe and a carbon source gas inlet pipe.

Preferably, the fluidized bed coating reaction chamber is a vertical fluidized bed.

Preferably, the fluidized coating unit further includes an exhaust device connected to the exhaust outlet.

Preferably, the fluidized coating unit further includes a product collecting device connected to the product outlet.

In a second aspect, the present invention provides a method for producing a silicon negative electrode material, the production method adopts the production system described in the first aspect, and the production method includes the following steps:

(1) Put the silicon oxide raw material into the vacuum reaction chamber, carry out the first heating reaction under vacuum to obtain silicon oxide vapor; at the same time, raise the deposition reaction chamber and the fluidized bed coating reaction chamber to a preset temperature and keep it warm;

(2) transporting the silicon dioxide vapor obtained in step (1) into the deposition reaction chamber, and performing a second heating reaction to obtain bulk silicon dioxide;

(3) transporting the massive silicon oxide obtained in step (2) to the fluidized bed device of the fluidized crushing unit for air crushing to obtain granular silicon oxide;

(4) The granular silicon oxide obtained in step (3) is transported to the fluidized bed coating reaction chamber, and the fluidized gas is introduced to fluidize the granular silicon oxide, and then the coating gas is introduced to carry out gas-phase carbon coating to obtain silicon dioxide. Negative material.

The production method of the present invention realizes the massive production of silicon oxide, particle crushing and carbon coating are carried out continuously, shortens the preparation period of the silicon negative electrode material, has simple preparation process, strong operability, safety, reliability, environmental friendliness and low cost ; The prepared silicon negative electrode material has performance advantages such as high cycle specific capacity and high cycle stability.

As a preferred technical solution of the present invention, the process of putting the silicon oxide raw material into the vacuum reaction chamber in the step (1) is controlled by the first valve.

Preferably, the temperature of the first heating reaction in step (1) is controlled by a first heating furnace.

Preferably, the degree of vacuum in step (1) is 0.01-100Pa, such as 0.01Pa, 0.05Pa, 0.1Pa, 0.3Pa, 0.5Pa, 0.8Pa, 1Pa, 3Pa, 5Pa, 8Pa, 10Pa, 13Pa, 16Pa , 18Pa, 20Pa, 25Pa, 30Pa, 40Pa, 50Pa, 60Pa, 70Pa, 80Pa, 90Pa or 100Pa, etc., but not limited to the listed values, other unlisted values within the above range of values are also applicable.

Preferably, the temperature of the first heating reaction in step (1) is 1100-1600°C, such as 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, 1350°C, 1400°C, 1450°C, 1500°C, 1550°C °C or 1600 °C, etc., the time is 4 to 24h, such as 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or 24h, etc., but not limited to the listed values, other values within the above range Values not listed also apply.

Preferably, in step (2), the process of transporting the bulk silicon oxide obtained in step (2) to the fluidized bed device of the fluidized crushing unit is controlled through a second valve.

Preferably, the temperature of the second heating reaction in step (2) is controlled by a second heating furnace.

Preferably, the temperature of the second heating reaction in step (2) is 500-900°C, such as 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C or 900°C, etc., The time is 2-8h, such as 2h, 3h, 4h, 5h, 6h, 7h or 8h, etc., but not limited to the listed values, and other unlisted values within the above range of values are also applicable.

Preferably, in step (4), the process of transporting the granular silicon oxide obtained in step (3) to the fluidized bed coating reaction chamber is controlled by a third valve.

Preferably, the temperature of the vapor-phase carbon coating in step (4) is controlled by a third heating furnace.

Preferably, the temperature of gas-phase carbon coating in step (4) is 600-1000°C, such as 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C, etc., The time is 0.5-2h, such as 0.5h, 0.8h, 1.1h, 1.4h, 1.7h or 2h, etc., but not limited to the listed values, and other unlisted values within the above range of values are also applicable.

As a preferred technical solution of the present invention, the fluidized bed device of the fluidized crushing unit described in step (3) is a fluidized bed airflow crushing device, and when the bulk silicon oxide is transported to the fluidized bed airflow crushing device for airflow After crushing, it is sent to the powder screening device, so that the coarse silicon oxide that has not passed the screening is returned to the fluidized bed jet crushing device for secondary crushing; the sieved particle silicon oxide is sent to A fluidized bed envelops the reaction chamber.

Preferably, the particle size of the sieved granular silica is 1-20 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm, etc., but not limited to the listed values, and other unlisted values within the above range of values are also applicable.

Preferably, the silicon anode material obtained in step (4) is collected and stored through a product collection device, and the tail gas generated in the fluidized bed coating reaction chamber is collected and post-treated through a tail gas device.

Preferably, the fluidizing gas in step (4) includes nitrogen and/or argon.

Preferably, the cladding gas in step (4) includes any one or a combination of at least two of methane, ethylene, acetylene or propylene.

Preferably, in step (4), based on the total volume of the fluidization gas and the cladding gas as 100%, the volume of the cladding gas accounts for 5% to 30%, such as 5%, 7%, 9%, 11%, 13%, 15%, 17%, 19%, 21%, 23%, 25%, 28% or 30%, etc., but not limited to the listed values, other values within the above range are not listed values are also applicable.

Preferably, in step (4), the total gas flow rate of the fluidization gas and the cladding gas is 0.1-2m/s, such as 0.1m/s, 0.3m/s, 0.5m/s, 0.7m/s s, 0.9m/s, 1.1m/s, 1.3m/s, 1.5m/s, 1.7m/s, 1.8m/s or 2m/s, etc., but not limited to the listed values, within the above range Other values not listed also apply.

As a preferred technical solution of the present invention, the production method comprises the following steps:

(1) Open the first valve, close the second valve and the third valve, put the silicon oxide raw material into the vacuum reaction chamber, close the first valve and vacuumize the vacuum reaction chamber to make the vacuum degree reach 0.01-100Pa, pass The first heating furnace raises the temperature of the vacuum reaction chamber to 1100-1600°C, and the first heating reaction is carried out for 4-24 hours to obtain silicon oxide vapor; at the same time, the deposition reaction chamber and the fluidized The bed-covered reaction chamber is raised to a preset temperature and kept warm;

(2) Transport the silicon dioxide vapor obtained in step (1) to the deposition reaction chamber, raise the temperature of the deposition reaction chamber to 500-900°C through the second heating furnace, and perform the second heating reaction for 2-8 hours to obtain massive silicon dioxide silicon;

(3) Open the second valve, transport the massive silicon oxide obtained in step (2) to the fluidized bed airflow pulverization device of the fluidized crushing unit, close the second valve, and the massive silicon oxide enters the Powder sieving device, after sieving, the coarse silicon oxide that has not passed the screening is returned to the fluidized bed jet milling device for secondary crushing, and the particle size of the sieved silicon oxide is 1-20 μm ;

(4) Open the third valve, send the silicon oxide granules with qualified particle size after sieving into the fluidized bed coating reaction chamber, close the third valve, and feed fluidizing gas into the fluidized bed coating reaction chamber. The fluidizing gas includes nitrogen and/or argon to fluidize the silicon oxide particles, and then pass through the covering gas, and the covering gas includes any one or at least two of methane, ethylene, acetylene or propylene. Combination, control the total volume of the fluidization gas and the cladding gas as 100%, the volume of the cladding gas accounts for 5% to 30%, and control the volume of the fluidizing gas and the cladding gas The total gas flow rate is 0.1-2m/s, and the temperature of the fluidized bed coating reaction chamber is raised to 600-1000°C through the third heating furnace, and the gas-phase carbon coating is carried out for 0.5-2h to obtain the silicon negative electrode material and enter the product collection device , the exhaust gas enters the exhaust device for post-treatment.

In a third aspect, the present invention provides a silicon negative electrode material obtained by the production method described in the second aspect.

In a fourth aspect, the present invention provides an application of the silicon negative electrode material described in the third aspect in an ion battery.

The numerical ranges described in the present invention not only include the above-listed point values, but also include any point values between the above-mentioned numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention will not exhaustively list the ranges. The specific pip value to include.

Compared with the prior art solutions, the present invention has at least the following beneficial effects:

(1) The present invention adopts a system integration design, which fully considers the connection and matching of equipment in each process section in the system, which is conducive to improving the efficiency and productivity of the production system;

(2) The production system of the present invention adopts a vertical fluidized bed reactor, and completes carbon coating on the surface of the material through chemical vapor deposition technology in a fluidized state, which not only can continuously produce high-performance silicon negative electrode materials, but also has a high yield , to ensure the continuity of the process, shorten the production cycle, and avoid the problems of agglomeration and uneven deposition caused by static accumulation of materials;

(3) The preparation method of the present invention is simple in process, strong in operability, safe and reliable, environment-friendly, and low in cost. The prepared silicon negative electrode material is applied to batteries and has high initial discharge specific capacity and 100-cycle capacity retention rate.

Description of drawings

Fig. 1 is the schematic diagram of the production system of silicon anode material described in embodiment 1;

In the figure: 1-Material bin, 2-First valve, 3-First heating furnace, 4-Vacuum reaction chamber, 5-Conveying device, 6-Second heating furnace, 7-Deposition reaction chamber, 8-Second valve , 9-fluidized bed jet crushing device, 10-powder screening device, 11-third valve, 12-third heating furnace, 13-fluidized bed coating reaction chamber, 14-tail gas device, 15-product collection device.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods. It should be clear to those skilled in the art that the examples are only for helping to understand the present invention, and should not be regarded as specific limitations on the present invention.

Example 1

This embodiment provides a production system for a silicon negative electrode material, as shown in Figure 1:

The production system sequentially includes a silicon oxide reaction generation unit, a fluidized crushing unit and a fluidized coating unit along the flow direction of the material;

The silicon oxide reaction generation unit includes a silo 1, a vacuum reaction chamber 4 and a deposition reaction chamber 7 sequentially connected along the material flow direction; a first valve 1 is arranged between the silo 1 and the vacuum reaction chamber 4 The vacuum reaction chamber 4 is heated by the first heating furnace 3, and the deposition reaction chamber 7 is heated by the second heating furnace 6, so that the temperature of the vacuum reaction chamber 4 is greater than the temperature of the deposition reaction chamber 7; The discharge port of the vacuum reaction chamber 4 is connected to the feed port of the deposition reaction chamber 7 through a conveying device 5,

The fluidized crushing unit includes a fluidized bed airflow crushing device 9 and a powder screening device 10 connected in sequence along the material flow direction, and the feed port of the fluidized bed airflow crushing device 9 is connected to the depositor through a second valve 8. The discharge port of the reaction chamber 7 is connected; the discharge port of the powder screening device 10 is divided into two paths, one of which is returned to the feed port of the fluidized bed jet crushing device 9, and the other path is used as the flow path. The outlet of chemical crushing unit;

The fluidized coating unit includes a fluidized bed coating reaction chamber 13; the fluidized bed coating reaction chamber 13 is a vertical fluidized bed, and is heated by a third heating furnace 12; the fluidized bed coating The feed port of the coating reaction chamber 13 is connected with the discharge port of the fluidized crushing unit through the third valve 11; the fluidized bed coating reaction chamber 13 is also provided with a fluidization gas inlet, a coating gas inlet, Tail gas outlet and product outlet; the fluidization gas inlet and the coating gas inlet are all independently arranged at the bottom of the fluidized bed coating reaction chamber 13, and are respectively connected with a fluidization gas inlet pipe and a carbon source gas Intake pipe; the tail gas outlet is arranged on the top of the fluidized bed-coated reaction chamber 13, and is connected with a tail gas device 14; the product outlet is connected with a product collection device 15.

The following application examples and application comparison examples all use the production system provided in Example 1.

Application example 1

This application example provides a production method of a silicon negative electrode material, the production method comprising the following steps:

(1) Open the first valve 1, close the second valve 8 and the third valve 11, put the silicon oxide raw material into the vacuum reaction chamber 4, and after closing the first valve 1, vacuumize the vacuum reaction chamber 4 to make the vacuum degree When it reaches 10Pa, the temperature of the vacuum reaction chamber 4 is raised to 1400°C through the first heating furnace 3, and the first heating reaction is carried out for 10 hours to obtain silicon oxide vapor; at the same time, the deposition reaction is respectively carried out through the second heating furnace 6 and the third heating furnace 12 Chamber 7 and fluidized bed coating reaction chamber 13 are raised to 600°C and 800°C and kept warm;

(2) Transport the silicon dioxide vapor obtained in step (1) to the deposition reaction chamber 7, raise the temperature of the deposition reaction chamber 7 to 600°C through the second heating furnace 6, and perform the second heating reaction for 4 hours to obtain bulk silicon oxide ;

(3) Open the second valve 8, transport the massive silicon dioxide obtained in step (2) to the fluidized bed airflow pulverization device 9 of the fluidized crushing unit, close the second valve 8, and the massive silicon dioxide is pulverized by airflow After the treatment, it enters the powder screening device 10, and the coarse particle silicon oxide that has not passed the screening after the screening process is returned to the fluidized bed jet milling device 9 to continue the secondary crushing treatment, and the particle silicon oxide that passes the screening is The particle size is 5μm;

(4) Open the third valve 11, send the granulated silica particles with qualified particle size after sieving into the fluidized bed coating reaction chamber 13, close the third valve 11, and pass into the fluidized bed coating reaction chamber 13. gas (nitrogen) to fluidize the silicon oxide particles, and then pass through the cladding gas (acetylene), the cladding gas includes any one or a combination of at least two of methane, ethylene, acetylene or propylene, and the control Taking the total volume of the fluidization gas and the cladding gas as 100%, the volume of the cladding gas accounts for 10%, and the total gas flow rate of the fluidizing gas and the cladding gas is controlled to be 1m/ s, and through the third heating furnace 12, the temperature of the fluidized bed coating reaction chamber 13 is raised to 800 ° C, and the gas phase carbon coating is carried out for 1 hour to obtain the silicon negative electrode material, which enters the product collection device 15, and the tail gas enters the tail gas device 14 for post-treatment .

Application example 2

This application example provides a production method of a silicon negative electrode material. In the production method, the degree of vacuum in step (1) is 100 Pa, the temperature of the vacuum reaction chamber 4 is 1600° C., and the holding time of the first heating reaction is 24 hours. ; The temperature of step (1) and (2) deposition reaction chamber 7 is 900 ℃, and the holding time of step (2) second heating reaction is 8h; Step (3) the granular silicon oxide particle size that passes sieving is 20 μ m; Step (1) and step (4) The temperature of the fluidized bed coating reaction chamber 13 is 1000 ° C, the fluidization gas in step (4) is argon, the coating gas is methane, and the coating gas The volume accounts for 30%, the total gas flow rate is 2m/s, and the holding time of gas-phase carbon coating is 2h. Except for the above, other conditions are exactly the same as Application Example 1.

Application example 3

This application example provides a production method of a silicon negative electrode material. In the production method, the degree of vacuum in step (1) is 0.01 Pa, the temperature of the vacuum reaction chamber 4 is 1100° C., and the holding time of the first heating reaction is 4h; the temperature of the deposition reaction chamber 7 in step (1) and step (2) is 500°C, and the holding time of the second heating reaction in step (2) is 2h; the particle size of the sieved silicon oxide in step (3) is 1 μm The temperature of step (1) and step (4) fluidized bed coating reaction chamber 13 is 600 ℃, the fluidization gas described in step (4) is argon, the described coating gas is ethylene, and the coating The volume of gas accounts for 5%, the total gas flow rate is 0.1m/s, and the holding time of gas-phase carbon coating is 0.5h. Except for the above, other conditions are exactly the same as those in Application Example 1.

Application Comparative Example 1

This application comparative example provides a production method of a silicon negative electrode material. In the production method, the fluidized bed coating reaction chamber 13 in step (4) does not pass into the fluidization gas, does not make the material in a fluidized state, and directly passes through Injecting coating gas for gas-phase carbon coating is equivalent to using a fixed-bed reactor for gas-phase coating. Except for this, other conditions are exactly the same as those in Application Example 1.

The silicon anode material prepared in Application Examples 1-3 and Application Comparative Example 1 is used as the anode material powder, and the ternary nickel-cobalt lithium manganese oxide cathode material and the supporting electrolyte are selected to assemble into a battery, using GB/T24533-2009 The test method was used to measure its electrochemical performance, including the first discharge specific capacity, first coulombic efficiency and 100-cycle capacity retention rate. The test results are shown in Table 1.

Table 1

project First discharge specific capacity first coulombic efficiency 100-cycle capacity retention Application example 1 1540mAh·g ^-1 85% 96% Application example 2 1400mAh·g ^-1 82% 94% Application example 3 1340mAh·g ^-1 80% 92% Application Comparative Example 1 1100mAh·g ^-1 65% 65%

It can be seen from Table 1:

(1) The system provided by the present invention is used to prepare silicon negative electrode materials. The production time is short, the yield is high, and it can be operated continuously. Excellent performance such as capacity retention;

(2) Based on the electrochemical properties tested in Table 1, it can be seen that the product powder prepared by using the system device and process method provided by the present invention has excellent electrochemical properties as the negative electrode material. However, when the fixed bed was used for coating in Comparative Example 1, the coating was unsuccessful because the powder could not be fluidized and flow inside the reactor.

The present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of selected components in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention. These simple modifications All belong to the protection scope of the present invention.

In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way if there is no contradiction. The combination method will not be described separately.

In addition, various combinations of different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

Claims (10)

1. The production system of the silicon cathode material is characterized by sequentially comprising a silicon oxide reaction generating unit, a fluidization crushing unit and a fluidization coating unit along the flow direction of the material;

the silicon oxide reaction generating unit comprises a vacuum reaction chamber and a deposition reaction chamber which are sequentially connected, wherein the temperature of the vacuum reaction chamber is higher than that of the deposition reaction chamber;

the fluidization crushing unit and the fluidization coating unit respectively comprise independently used fluidized bed devices for respectively performing airflow crushing and gas phase coating, wherein the fluidized bed devices of the fluidization coating unit comprise a fluidized bed coating reaction chamber.

2. The production system of claim 1, wherein the vacuum reaction chamber is heated by a first heating furnace;

preferably, the silicon oxide reaction production unit further comprises a feed bin, and a discharge hole of the feed bin is connected with the vacuum reaction chamber;

preferably, the bin is connected with the vacuum reaction chamber through a first valve;

preferably, the deposition reaction chamber is heated by a second heating furnace;

preferably, the discharge port of the vacuum reaction chamber is connected with the feed port of the deposition reaction chamber through a conveying device, and the discharge port of the deposition reaction chamber is the discharge port of the silicon oxide reaction generating unit.

3. The production system according to claim 1 or 2, wherein the fluidized bed device of the fluidized crushing unit is a fluidized bed jet mill, and a feed inlet of the fluidized bed jet mill is connected with a discharge outlet of the silica reaction generating unit;

preferably, the feed inlet of the fluidized bed jet mill is connected with the discharge outlet of the silica reaction generating unit through a second valve;

preferably, the fluidization crushing unit further comprises a powder sieving device;

preferably, a discharge port of the fluidized bed jet mill is connected with a feed port of the powder screening device;

preferably, the discharge port of the powder screening device is divided into two paths, one path returns to the feed port of the fluid bed jet mill, and the other path is used as the discharge port of the fluid crushing unit.

4. A production system according to any one of claims 1-3, wherein the fluidized bed apparatus of the fluidized coating unit further comprises a third heating furnace for heating the fluidized bed coating reaction chamber, the feed inlet of the fluidized bed coating reaction chamber being connected to the discharge outlet of the fluidized crushing unit;

preferably, the feed inlet of the fluidized bed coating reaction chamber is connected with the discharge port of the fluidization breaking unit through a third valve;

preferably, the fluidized bed coating reaction chamber is provided with a fluidization gas inlet, a coating gas inlet, a tail gas outlet and a product outlet;

preferably, the fluidization gas inlet and the cladding gas inlet are respectively and independently arranged at the bottom of the fluidized bed cladding reaction chamber, and are respectively connected with a fluidization gas inlet pipe and a carbon source gas inlet pipe;

preferably, the fluidized bed coating reaction chamber is a vertical fluidized bed;

preferably, the fluidization coating unit further comprises a tail gas device connected with the tail gas outlet;

preferably, the fluidized coating unit further comprises a product collecting device connected to the product outlet.

5. A method for producing a silicon anode material, characterized by using the production system according to any one of claims 1 to 4, comprising the steps of:

(1) Putting a silicon oxide raw material into a vacuum reaction chamber, and performing a first heating reaction under vacuum to obtain silicon oxide vapor; simultaneously, the deposition reaction chamber and the fluidized bed coating reaction chamber are heated to a preset temperature and are insulated;

(2) Delivering the silica vapor obtained in the step (1) into the deposition reaction chamber, and performing a second heating reaction to obtain massive silica;

(3) Conveying the massive silica obtained in the step (2) into a fluidized bed device of a fluidization crushing unit for airflow crushing to obtain granular silica;

(4) And (3) conveying the granular silicon oxide obtained in the step (3) to a fluidized bed coating reaction chamber, introducing fluidizing gas to fluidize the granular silicon oxide, and introducing coating gas to carry out gas-phase carbon coating to obtain the silicon anode material.

6. The method according to claim 5, wherein the process of charging the silicon oxide raw material into the vacuum reaction chamber in the step (1) is controlled by a first valve;

preferably, the temperature of the first heating reaction of step (1) is controlled by a first heating furnace;

preferably, the vacuum degree of the vacuum in the step (1) is 0.01-100 Pa;

preferably, the temperature of the first heating reaction in the step (1) is 1100-1600 ℃ and the time is 4-24 hours;

preferably, the process of delivering the bulk silica obtained in the step (2) to the fluidized bed device of the fluidization and crushing unit in the step (2) is controlled by a second valve;

preferably, the temperature of the second heating reaction of step (2) is controlled by a second heating furnace;

preferably, the temperature of the second heating reaction in the step (2) is 500-900 ℃ and the time is 2-8 h;

preferably, the process of delivering the granular silicon oxide obtained in the step (3) to the fluidized bed coating reaction chamber in the step (4) is controlled by a third valve;

preferably, the temperature of the gaseous carbon coating of step (4) is controlled by a third heating furnace;

preferably, the temperature of the gas-phase carbon coating in the step (4) is 600-1000 ℃ and the time is 0.5-2 h.

7. The production method according to claim 5 or 6, wherein the fluidized bed device of the fluidized crushing unit in the step (3) is a fluidized bed jet mill, and when bulk silica is fed into the fluidized bed jet mill for jet crushing, the bulk silica is fed into a powder sieving device, so that coarse silica particles which have not passed sieving are returned to the fluidized bed jet mill for secondary crushing treatment; conveying the sieved granular silicon oxide to a fluidized bed coating reaction chamber;

preferably, the particle size of the sieved granular silicon oxide is 1-20 μm;

preferably, the silicon anode material obtained in the step (4) is collected and stored through a product collecting device, and tail gas generated by the fluidized bed coating reaction chamber is collected and post-treated through a tail gas device;

preferably, the fluidizing gas of step (4) comprises nitrogen and/or argon;

preferably, the coating gas of step (4) comprises any one or a combination of at least two of methane, ethylene, acetylene or propylene;

preferably, in the step (4), the volume of the coating gas is 5% -30% based on 100% of the total volume of the fluidization gas and the coating gas;

preferably, in the step (4), the total gas flow rate of the fluidizing gas and the coating gas is 0.1 to 2m/s.

8. The production method according to any one of claims 5 to 7, characterized in that the production method comprises the steps of:

(1) Opening a first valve, closing a second valve and a third valve, putting the silicon oxide raw material into a vacuum reaction chamber, vacuumizing the vacuum reaction chamber after the first valve is closed to enable the vacuum degree to reach 0.01-100 Pa, lifting the temperature of the vacuum reaction chamber to 1100-1600 ℃ through a first heating furnace, and performing a first heating reaction for 4-24 hours to obtain silicon oxide steam; simultaneously, the deposition reaction chamber and the fluidized bed coating reaction chamber are respectively heated to a preset temperature through a second heating furnace and a third heating furnace and are insulated;

(2) Conveying the silica vapor obtained in the step (1) to a deposition reaction chamber, lifting the temperature of the deposition reaction chamber to 500-900 ℃ by a second heating furnace, and performing a second heating reaction for 2-8 h to obtain massive silica;

(3) Opening a second valve, conveying the massive silica obtained in the step (2) into a fluid bed jet milling device of a fluid-bed crushing unit, closing the second valve, enabling the massive silica to enter a powder screening device after jet milling treatment, returning the coarse granular silica which is not screened after screening treatment into the fluid bed jet milling device for secondary milling treatment, wherein the granularity of the granular silica which is screened is 1-20 mu m;

(4) Opening a third valve, sending the sieved granular silica particles with qualified granularity into a fluidized bed coating reaction chamber, closing the third valve, introducing fluidizing gas into the fluidized bed coating reaction chamber, wherein the fluidizing gas comprises nitrogen and/or argon, fluidizing the silica particles, then introducing coating gas, wherein the coating gas comprises any one or a combination of at least two of methane, ethylene, acetylene and propylene, controlling the total volume of the fluidizing gas and the coating gas to be 100%, controlling the volume of the coating gas to be 5% -30%, controlling the total gas flow rate of the fluidizing gas and the coating gas to be 0.1-2 m/s, lifting the temperature of the fluidized bed coating reaction chamber to be 600-1000 ℃ through a third heating furnace, coating gas phase carbon for 0.5-2 h to obtain a silicon anode material, entering a product collecting device, and enabling tail gas to enter a tail gas device for post treatment.

9. A silicon negative electrode material obtained by the production method according to any one of claims 5 to 8.

10. Use of the silicon negative electrode material of claim 9 in an ion battery.