Integrated preparation system and method of silicon-oxygen negative electrode material

Abstract

This invention discloses an integrated preparation system and method for silicon-oxygen anode materials. The system includes a silicon monoxide generation device, a vaporization chamber, a reaction deposition chamber, and a graded discharge device connected in sequence. The silicon monoxide generation device is connected to an inert dilution gas source. The vaporization chamber is connected to a dopant supply device and a lithium source supply device. The head of the reaction deposition chamber is connected to a carbon source gas supply device, and the tail is connected to a vacuum pump. The preparation method includes preparing fumed silicon monoxide, fumed dopant, and fumed lithium source. Fumed silicon monoxide, fumed dopant, fumed lithium source, and fumed carbon source are fed into the reaction deposition chamber in a specific order using inert gas. Silicon monoxide deposition, doping, lithium replenishment, and carbon coating are completed in a specific order. After graded shaping, the silicon-oxygen anode material is obtained. This invention integrates silicon monoxide preparation, fumed doping, carbon coating, and lithium replenishment processes, reducing equipment investment and energy consumption, and ensuring the uniformity and consistency of doping, lithium replenishment, and carbon coating.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to an integrated preparation system and method for silicon-oxygen anode materials. Background Technology

[0002] Lithium-ion batteries are widely used in smartphones, electric vehicles, and energy storage. With the increasing power consumption of smart devices and the urgent need for longer driving ranges in electric vehicles, lithium-ion batteries require higher energy densities. Improving the energy density of lithium-ion batteries mainly relies on increasing the specific capacity of the cathode and anode materials and increasing the voltage difference between the positive and negative electrodes. Currently, anode materials are mainly carbon-based, including natural and artificial graphite, but their relatively low theoretical specific capacity (372 mAh / g) is insufficient to meet the demands of higher energy densities (350-450 Wh / kg) in lithium-ion battery cells. Among many alternative materials, silicon, with its high theoretical specific capacity (4200 mAh / g), has become the most promising material to replace graphite anodes. However, pure silicon anodes face problems such as large volume expansion (over 300%), unstable SEI film (solid electrolyte interface film), and low conductivity, limiting their practical application. Currently, nano-sizing and carbon composite methods can alleviate these problems to some extent, but they have not yet reached practical application levels.

[0003] Although the theoretical specific capacity of silicon monoxide composite materials (2000 mAh / g) is lower than that of pure silicon anodes, it is still more than five times that of graphite anodes. In terms of design, it can fully meet the energy density requirement of 450 Wh / kg for lithium-ion battery cells. Furthermore, due to the presence of oxygen as a volume buffer during the lithium insertion / extraction process, it exhibits a smaller volume expansion effect (less than 150%) and superior cycle stability compared to pure silicon anode materials, making it the most promising high-capacity anode material for large-scale application.

[0004] However, silicon monoxide has poor electronic conductivity and still exhibits a larger volume expansion effect than graphite anodes (less than 20%). This significant lithium insertion / extraction expansion leads to the rupture and regeneration of the SEI film formed on the anode. Hydrofluoric acid, after film rupture, corrodes the silicon-based anode, increasing reversible capacity loss and reducing the initial coulombic efficiency and cycle stability of lithium-ion batteries. Simultaneously, due to the presence of oxygen in silicon monoxide, some active lithium is consumed during the initial lithium insertion process to form lithium oxide, resulting in a theoretical initial coulombic efficiency of only 77%. Therefore, improving the electronic conductivity of silicon monoxide, compensating for the initial coulombic efficiency, and mitigating the volume effect are key aspects for the large-scale application of silicon monoxide.

[0005] To address the aforementioned conductivity issues, patent CN108172775A discloses a phosphorus-doped silicon-carbon anode material for lithium-ion batteries and its preparation method. This method improves the electronic conductivity of nano-silicon through phosphorus doping and mitigates the volume effect of silicon through carbon coating. However, due to insufficient strength and density of the carbon coating layer, it is prone to cracking during cycling, resulting in a short cycle life. To improve the initial coulombic efficiency, patent CN105489846A discloses an electrode lithium replenishment method and system. Specifically, it involves combining a lithium strip and an electrode to be replenished to form a lithium-replenishing composite electrode, thus improving the initial coulombic efficiency of the anode material. However, electrode lithium replenishment is highly dependent on equipment; after lithium consumption, gaps remain, affecting the battery interface. Furthermore, lithium replenishment only occurs on the electrode surface, resulting in poor uniformity and potential lithium deficiency or excess.

[0006] Meanwhile, the existing technology involves many steps, and each step, such as carbon coating and lithium replenishment, requires heating and cooling. This results in large equipment investments, high energy consumption, and insufficient utilization of cooling heat, leading to long processing times. Furthermore, the step-by-step preparation process is detrimental to the uniformity and consistency of the materials. No matter how the conditions are optimized, the results of the later-stage processes will affect the results of the earlier-stage processes, thereby impacting the overall performance and consistency of carbon coating, lithium replenishment, and other processes. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an integrated preparation system and method for silicon-oxygen anode materials, which integrates silicon monoxide preparation, gas phase doping, CVD carbon coating and CVD lithium replenishment processes, thereby reducing equipment investment and energy consumption, and ensuring the uniformity and consistency of doping, lithium replenishment and carbon coating.

[0008] This invention provides the following technical solution:

[0009] In one aspect, an integrated preparation system for silicon-oxygen anode materials is provided, comprising a silicon monoxide generation device, a gasification chamber, a reaction deposition chamber, and a graded discharge device connected in sequence.

[0010] The silica generating device is connected to an inert dilution gas source.

[0011] The vaporization chamber is connected to a dopant supply device and a lithium source supply device;

[0012] The head of the reaction deposition chamber is connected to a carbon source gas supply device, and the tail is connected to a vacuum pump.

[0013] Furthermore, the vacuum pump is connected to a tail gas recovery device; the reaction deposition chamber is provided with an upper fluid baffle connected to the top and a lower fluid baffle connected to the bottom, the upper fluid baffle and the lower fluid baffle are distributed alternately and a fluid channel is formed between them.

[0014] In a second aspect, a method for preparing silicon-oxygen anode materials using the system described in the first aspect is provided, comprising the following steps:

[0015] Gas-phase silicon monoxide is prepared in a silicon monoxide generation apparatus.

[0016] The dopant supply device quantitatively supplies dopant into the vaporization chamber and generates gaseous dopant in the vaporization chamber;

[0017] The lithium source supply device provides a quantitative amount of lithium source to the gasification chamber and generates gaseous lithium source in the gasification chamber;

[0018] The carbon source supply device provides a gaseous carbon source to the head of the reaction deposition chamber;

[0019] Under vacuum conditions, inert gas provided by an inert dilution gas source is used to guide and push gaseous silicon monoxide and gaseous dopants into the reaction deposition chamber in sequence. The deposition and doping of silicon monoxide are completed in sequence. Then, gaseous lithium source and gaseous carbon source are pushed into the reaction deposition chamber in any order or simultaneously to complete the lithium replenishment and carbon coating of silicon monoxide and obtain solid products.

[0020] The solid product is graded and shaped in a grading and discharging device to obtain silicon-oxygen anode material.

[0021] Furthermore, the inert gas is one of high-purity argon, helium, nitrogen, an argon-hydrogen mixture, and a nitrogen-hydrogen mixture.

[0022] Furthermore, the raw materials for preparing fumed silica are silicon powder and silica powder, wherein the molar ratio of silicon powder to silica powder is 3 to 0.5:1.

[0023] Furthermore, the dopant is one or more of organophosphorus, inorganic phosphorus, organoboron, and inorganic boron, preferably one or more of phosphorus oxychloride, phosphorus pentachloride, phosphorus oxybromide, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, boric acid, boron oxide, boron tribromide, trimethyl borate, triethyl borate, and tripropyl borate.

[0024] Furthermore, the lithium source is one of elemental lithium, lithium oxide, lithium sulfide, lithium halide, lithium salt, or other lithium compounds.

[0025] Furthermore, the gaseous carbon source is one or more of methane, acetylene, ethanol, methanol, acetaldehyde, and gaseous alkanes.

[0026] Furthermore, before preparing fumed silica, the raw materials, dopants, and lithium source of silica are respectively loaded into the silica generating device, the dopant supply device, and the lithium source supply device; the vacuum pump is started to the vacuum degree inside the silica generating device to 10-1000 Pa, and the inert gas flow rate is adjusted to 0.1-10 L; the preset temperature of the vaporization chamber is 1200-1500℃, and the preset temperature of the reaction deposition chamber is 600-1100℃. Then, the temperature of the silica generating device is adjusted to 1300-1800℃ to obtain fumed silica.

[0027] Furthermore, the reaction deposition chamber is pre-set with two or more temperature zones, and the temperature difference between two adjacent temperature zones is 100 to 300°C.

[0028] Furthermore, the heating methods for the silicon monoxide generation device, the vaporization chamber, and the reaction deposition chamber are one or more of the following: resistance wire heating, medium- and high-frequency induction heating, graphite heating element heating, plasma radiation heating, and microwave heating.

[0029] Furthermore, the reaction time for silicon monoxide doping is 1–1000 min, the reaction time for lithium supplementation is 1–1000 min, and the reaction time for carbon coating is 1–1000 min.

[0030] Furthermore, the reaction deposition chamber is cooled to 25–100°C after the reaction is completed.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] (1) The integrated preparation system for silicon-oxygen anode materials provided by the present invention integrates silicon monoxide preparation, gas phase doping, CVD carbon coating and CVD lithium replenishment processes into one, which is simple to operate and can simplify the process flow, reduce equipment investment, reduce floor space and reduce energy consumption.

[0033] (2) The integrated preparation system for silicon-oxygen anode materials provided by the present invention is fully enclosed and uses inert gas to transport the reactants, which reduces the possibility of contamination and oxidation. The entire gas phase process avoids the introduction of magnetic materials.

[0034] (3) The preparation method of silicon-oxygen anode material provided by the present invention is that the doping process begins in the gaseous state of silicon monoxide, and the atomic or molecular level mixed doping is more uniform and sufficient.

[0035] (4) The method for preparing silicon-oxygen anode material provided by the present invention adopts CVD for both lithium replenishment and carbon coating. The atomized uniform coating is applied to the surface of silicon monoxide particles in the aging process, and the reaction time is short. At the same time, since silicon monoxide is in the deposition and aging state, it has the characteristics of internal fluffiness and high surface activity. Internal fluffiness is conducive to the rapid and uniform diffusion and penetration of lithium atoms, and high surface activity is conducive to the efficient and rapid carbonization deposition of gaseous carbon source. It has strong adhesion and high stability, thus avoiding the technical problems of local lithium enrichment and uneven coating in existing processes.

[0036] (5) The preparation method of silicon-oxygen anode material provided by the present invention can flexibly design and adjust the particle size distribution of the product by adjusting the process sequence of carbon coating and lithium replenishment. If lithium replenishment is performed first and then carbon coating, the particle size is larger; if carbon coating is performed first and then lithium replenishment is performed, the particle size is smaller; if lithium replenishment and carbon coating are performed simultaneously, the particle size is between the two aforementioned situations. Therefore, there is no need for subsequent high-energy-consuming process steps such as crushing.

[0037] (6) The present invention realizes the integrated preparation process of silicon-oxygen anode material through an integrated preparation system, avoiding the intermediate process of reheating and cooling, cleverly avoiding the technical problems of coating layer peeling and grain coarsening caused by the downstream process to the upstream process, and the preparation system can effectively adjust the reaction temperature, which is beneficial to the control of reaction conditions. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the integrated preparation system for silicon-oxygen anode materials in an embodiment of the present invention;

[0039] Figure 2 SEM image of the product in Embodiment 2 of this invention;

[0040] Figure 3 Charge-discharge curves of the button cell battery in Embodiment 2 of this invention;

[0041] Figure 4 SEM image of the product in Embodiment 3 of this invention;

[0042] Figure 5 Charge-discharge curves of the button cell battery in Embodiment 3 of this invention;

[0043] Figure 6 SEM image of the product in Embodiment 4 of this invention;

[0044] Figure 7 Charge-discharge curves of the button cell battery in Embodiment 4 of this invention;

[0045] Figure 8 Product cycle performance diagrams for embodiments 2, 3, and 4 of this invention;

[0046] The following are marked in the diagram: 1. Inert dilution gas source; 2. Silica generation device; 3. Dopant supply device; 4. Lithium source supply device; 5. Gasification chamber; 6. Carbon source gas supply device; 7. Reaction deposition chamber; 8. Upper fluid baffle; 9. Fluid channel; 10. Vacuum pump; 11. Graded discharge device; 12. Tail gas recovery device; 13. Lower fluid baffle. Detailed Implementation

[0047] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0048] Example 1

[0049] like Figure 1 As shown, this embodiment provides an integrated preparation system for silicon-oxygen anode materials, including a silicon monoxide generation device 2, a vaporization chamber 5, a reaction deposition chamber 7, and a graded discharge device 11 connected in sequence; the silicon monoxide generation device 2 is connected to an inert dilution gas source 1 through a closed pipe; the vaporization chamber 5 is connected to a dopant supply device 3 and a lithium source supply device 4 through a closed pipe; the head of the reaction deposition chamber 7 is connected to a carbon source gas supply device 6 through a closed pipe, and the tail is connected to a vacuum pump 10, which is connected to a tail gas recovery device 12.

[0050] Inert gas source 1 is used to provide inert gas of a certain purity and flow rate to guide the transport of reactants or dilute reactants to control the reaction amount; the inert gas flows through the silicon monoxide generating device 2, the gasification chamber 5, and the reaction deposition chamber 7 in sequence through a closed pipeline, and is finally drawn into the tail gas recovery device 12 by the vacuum pump 10 for recovery treatment.

[0051] The silicon monoxide generating apparatus 2 is used to prepare gaseous silicon monoxide at a certain temperature and vacuum.

[0052] The dopant supply device 3 is used to quantitatively supply dopant. The dopant is quantitatively transported to the vaporization chamber 5 through a closed pipeline, where it is vaporized or cracked at high temperature, and then pushed to the reaction deposition chamber 7 under the dilution and guidance of inert gas.

[0053] The lithium source supply device 4 is used to quantitatively supply lithium source. The lithium source is quantitatively transported to the gasification chamber 5 through a closed pipeline, where it is gasified or cracked at high temperature, and then pushed to the reaction deposition chamber 7 under the dilution and guidance of inert gas.

[0054] The vaporization chamber 5 is used as a closed pipe to guide gas or gaseous solids. It can also be used as a vaporization or cracking vaporization chamber for dopants or lithium sources, generating gaseous dopants or gaseous lithium sources under high temperature and vacuum.

[0055] The carbon source supply device 6 is used to quantitatively supply gaseous carbon source. Under the guidance and dilution of inert gas, the gaseous carbon source can be further diluted and quantitatively guided to the reaction deposition chamber 7, making the reaction itself more controllable.

[0056] The reaction deposition chamber 7 is used to complete the deposition, doping, lithium replenishment, and carbon coating of silicon monoxide in a specific sequence. The reaction deposition chamber 7 is equipped with an upper fluid baffle 8 connected to the top and a lower fluid baffle 13 connected to the bottom. The upper fluid baffle 8 and the lower fluid baffle 13 are distributed alternately, forming a fluid channel 9 between them. The interior of the reaction deposition chamber 7 is divided into two or more regions, each with an independent heating zone, to create different temperature fields and promote uniform and efficient reaction.

[0057] Vacuum pump 10 is used to create a vacuum environment, which can lower the boiling point of solid substances and also act as a guide. Tail gas recovery device 12 is connected to vacuum pump 10 and is used to treat the waste gas generated during the reaction process to reduce environmental pollution.

[0058] The graded discharge device 11 is connected to the outlet end of the reaction sedimentation chamber 7 and is used to grade the reacted material.

[0059] Example 2

[0060] This embodiment provides a method for preparing silicon-oxygen anode materials using the system described in Example 1. The specific steps are as follows:

[0061] S1. A silicon powder and a silicon dioxide powder with a molar ratio of 1.5:1 are loaded into the silicon monoxide generating device 2. A lithium source (metallic lithium powder, molar ratio calculated according to lithium atoms) with a silicon dioxide powder molar ratio of 2.4 times is loaded into the lithium source supply device 4. A dopant phosphorus pentoxide powder with a dopant mass ratio of 1% silicon dioxide powder is loaded into the dopant supply device 3.

[0062] S2. Start vacuum pump 10 until the entire system is under negative pressure (vacuum degree 50Pa), turn off vacuum pump 10, maintain for 2 hours, and the vacuum degree should not exceed 60Pa; turn on inert dilution gas source 1, and fill silicon monoxide generation device 2, dopant supply device 3, lithium source supply device 4, vaporization chamber 5, reaction deposition chamber 7 and graded discharge device 11 with inert high-purity argon gas, and balance the gas pressure with the atmosphere.

[0063] S3. Close the physical transmission connections of the dopant supply device 3, lithium source supply device 4, carbon source gas supply device 6, and graded discharge device 11 to the vaporization chamber 5 and reaction deposition chamber 7, respectively. Restart the vacuum pump to evacuate the system to a vacuum level below 50 Pa. At the same time, introduce high-purity argon gas at a flow rate of 2 L / min. Set the preset temperature in the vaporization chamber 5 to 1300℃ and the preset temperatures in the reaction deposition chamber 7 to 700℃ in the front section, 900℃ in the middle section, and 600℃ in the rear section.

[0064] S4. After the temperatures in the vaporization chamber 5 and the reaction deposition chamber 7 stabilize, the temperature in the silicon monoxide generating device 2 is adjusted to 1400℃. Under these conditions, silicon powder and silicon dioxide powder react to form gaseous silicon monoxide. Under vacuum and argon flow, it is pushed through the vaporization chamber 5 to the reaction deposition chamber 7 for deposition and ripening. When the temperature in the silicon monoxide generating device 2 stabilizes at 1400℃, the connection between the dopant supply device 3 and the vaporization chamber 5 is opened, and the release rate of the dopant is controlled (the dopant supply device 3 has a certain pressure, and the vaporization chamber 5 is under a certain negative pressure, which has the function of directional flow). The dopant phosphorus pentoxide released into the vaporization chamber 5 rapidly vaporizes and sublimates at 1300℃. The mixed silicon monoxide vapor undergoes a doping reaction under vacuum and high-purity argon flow, and diffuses into the reaction deposition chamber 7 for further deposition and ripening to obtain doped silicon monoxide. The tail gas generated in the reaction is pumped to the tail gas recovery device 12 by a vacuum pump to ensure that harmful gases are 100% recovered and do not pollute the environment.

[0065] S5. When no flue gas is observed to be generated in the reaction window of the silicon monoxide generation device 2, the connecting pipe between the lithium source supply device 4 and the gasification chamber 5 is opened, and a quantitative amount of metallic lithium powder is released into the gasification chamber 5 for gasification at 1300℃. At the same time, the flow rate of high-purity argon is adjusted to 5L / min to dilute the lithium vapor and guide it to the reaction deposition chamber 7 under vacuum. At this time, the vacuum in the reaction deposition chamber 7 is maintained at about 50Pa. Gas phase lithium atoms pass through the fluid channel 9 and flow turbulently through the maturing doped silicon monoxide, where atomic deposition and reaction occur on the particle surface. The deposition time is controlled to be 10min to complete the lithium replenishment. The tail gas generated during the lithium replenishment process is pumped to the tail gas recovery device 12 by the vacuum pump 10 for treatment before being discharged in compliance with regulations.

[0066] S6. After lithium replenishment is completed, open the connecting pipeline between the carbon source gas supply device 6 and the reaction deposition chamber 7. The carbon source gas supply device 6 contains acetylene gas, and the flow rate is adjusted to 2L / min. At the same time, adjust the flow rate of high-purity argon gas to 2L / min to maintain the vacuum degree in the reaction deposition chamber 7 at about 50Pa. The acetylene gas enters the fluid channel 9 and contacts the surface of the silicon monoxide particles after lithium replenishment. Carbon deposition is carried out for 180 minutes to complete the carbon coating process of CVD. The generated tail gas is pumped to the tail gas treatment device 12 by the vacuum pump 10 and then discharged in compliance with regulations.

[0067] S7. After deposition, co-doping, lithium replenishment and carbon coating, the silicon monoxide anode powder is cooled to room temperature and conveyed to the classification and discharge device 11. The particle size is classified under the protection of high-purity argon gas, and the particles are screened and recovered by the classification equipment, which is mainly an air jet mill. The classification is carried out under the protection of argon gas, and the particles are recovered in combination with a bag filter recovery device to finally obtain qualified silicon monoxide powder.

[0068] Example 3

[0069] This embodiment provides a method for preparing silicon-oxygen anode materials, which differs from Embodiment 2 in that steps S5 and S6 are reversed compared to S5 and S6 in Embodiment 2, as detailed below:

[0070] S5. When no flue gas is observed to be generated in the reaction window of the silicon monoxide generation device 2, open the connecting pipeline between the carbon source gas supply device 6 and the reaction deposition chamber 7. The carbon source gas supply device 6 contains acetylene gas, and the flow rate is adjusted to 2L / min. At the same time, the flow rate of high-purity argon gas is adjusted to 2L / min to maintain the vacuum degree in the reaction deposition chamber 7 at about 50Pa. The acetylene gas enters the fluid channel 9 and contacts the surface of the lithium-added silicon monoxide particles. Carbon deposition is carried out for 180 minutes to complete the carbon coating process of CVD. The generated tail gas is pumped to the tail gas treatment device 12 by the vacuum pump 10 and then discharged in compliance with regulations.

[0071] S6. Open the connecting pipe between the lithium source supply device 4 and the vaporization chamber 5, and release a quantitative amount of metallic lithium powder into the vaporization chamber 5 for vaporization treatment at 1300℃. At the same time, adjust the flow rate of high-purity argon gas to 5L / min to dilute the lithium vapor and guide it to the reaction deposition chamber 7 under vacuum. At this time, the vacuum in the reaction deposition chamber 7 is maintained at about 50Pa. Gas phase lithium atoms pass through the fluid channel 9 and flow turbulently through the maturing doped silicon monoxide, where atomic deposition and reaction occur on the particle surface. Control the deposition time to 10min to complete the lithium replenishment. The tail gas generated during the lithium replenishment process is pumped by the vacuum pump 10 to the tail gas recovery device 12 for treatment before being discharged in compliance with regulations.

[0072] Example 4

[0073] This embodiment provides a method for preparing silicon-oxygen anode materials, which differs from Embodiment 2 in that: in step S5, the deposition time for lithium replenishment is controlled to be 100 min; in step S6, the carbonization deposition time for carbon coating is controlled to be 360 ​​min.

[0074] Example 5

[0075] This embodiment provides a method for preparing silicon-oxygen anode materials, which differs from Embodiment 2 in that the molar ratio of silicon powder to silicon dioxide powder in step S1 is 0.5:1.

[0076] Example 6

[0077] This embodiment provides a method for preparing silicon-oxygen anode materials. The difference from Embodiment 2 is that in step S4, after the temperature in the vaporization chamber 5 and the reaction deposition chamber 7 stabilizes, the temperature in the silicon monoxide generating device 2 is adjusted to 1800°C, while other conditions remain unchanged.

[0078] Performance Characterization

[0079] 1. SEM analysis was performed on the silica powders prepared in Examples 2-4, and the results are as follows: Figure 2 , Figure 4 and Figure 6 As shown in the figure, the product size is slightly smaller and more uniformly distributed after carbon coating and pre-lithiation. Extending the carbon coating and pre-lithiation time results in more carbon powder floating in the product, leading to poor product quality uniformity. This indicates that achieving uniform reaction by controlling the carbon coating and lithium addition within a shorter time is optimal.

[0080] 2. Using Shin-Etsu Chemical products from Japan as a comparative example, electrochemical tests were conducted on the comparative example and the silicon monoxide powder prepared in Examples 2-6. The specific steps are as follows:

[0081] (1) Mix silicon monoxide powder, PAA (polyacrylic acid) and SP (conductive carbon black) in a mass ratio of 8:1:1, grind them evenly by hand in an agate mortar, and adjust them into an aqueous paste.

[0082] (2) The mixed slurry was coated onto a copper foil with a thickness of 10 micrometers using a scraper with a slit of 250 μm. After coating, it was dried under vacuum at 100°C for 10 hours. It was then rolled to a thickness of 100 μm using a manual roller press and punched into a circular electrode sheet with a diameter of 12 mm. The electrode sheet was weighed and the weight of the active material was calculated. It was then placed in a glove box overnight.

[0083] (3) The next day, CR2016 button batteries were assembled in a glove box with lithium metal as the counter electrode, PE (polyethylene) membrane as the separator, lithium salt concentration of 1M LiFP6 (hexafluorophosphate), solvent ratio of EC (ethylene carbonate): EMC (ethyl methyl carbonate) = 3:7w%, and electrolyte containing 5% (w%) FEC (fluoroethylene carbonate) additive.

[0084] (4) The button cell battery was left to stand at room temperature for 12 hours and then constant current charge and discharge test was performed on the Blue Electric test system. The battery was discharged to 5mV at 0.1C, then discharged to 5mV at 0.02C constant current, and then charged to 1.5V at 0.1C.

[0085] The charge-discharge curves of Examples 2-4 are shown below. Figure 3 , Figure 5 and Figure 7The product cycle performance comparison in Examples 2-4 is as follows: Figure 8 As shown, the electrochemical data of the comparative examples and Examples 2-6 are summarized in Table 1.

[0086] Table 1 Summary of electrochemical data for comparative examples and Examples 2-6

[0087]

[0088]

[0089] Note: In Table 1, the capacity retention after 100 cycles is based on the initial charge capacity.

[0090] A comparison of Examples 2 and 3 illustrates that the order of the lithium replenishment and carbon coating processes has a significant impact on the specific capacity, initial efficiency, and cycle stability of the silicon-oxygen anode: Alloying followed by carbon coating results in the latter coating process affecting the former, causing grain coarsening, larger particles, lower specific capacity, weaker cycle stability, and higher initial efficiency; while carbon coating followed by alloying allows for effective control of particle size, greatly improving both specific capacity and cycle stability, although the initial coulombic efficiency is slightly lower.

[0091] A comparison of Examples 2 and 4 shows that extending the lithium replenishment time and carbon coating time reduces specific capacity and cycle stability, especially the cycle stability deteriorates significantly, even though the initial coulombic efficiency increases to 95%. This may be due to prolonged high-temperature annealing, which causes deep lithiation and coarsening of silicon grains.

[0092] A comparison of Examples 2 and 5 shows that the ratio of silicon powder to silica powder has a significant impact on the capacity and initial efficiency of the final product; the higher the proportion of silica, the worse the performance.

[0093] A comparison of Examples 2 and 6 shows that increasing the preparation temperature of silicon monoxide can improve the capacity and initial efficiency of the final product.

[0094] The overall electrochemical performance of Examples 2-6 is superior to that of the best existing lithium replenishment products (comparative examples).

[0095] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An integrated preparation system for silicon-oxygen anode materials, characterized in that, It includes a silica generation device, a gasification chamber, a reaction deposition chamber, and a graded discharge device connected in sequence. The silica generating apparatus is connected to an inert dilution gas source, and the silica generating apparatus is used to prepare gaseous silica. The vaporization chamber is connected to a dopant supply device and a lithium source supply device; the dopant supply device is used to quantitatively supply dopant to the vaporization chamber and generate gaseous dopant in the vaporization chamber; the lithium source supply device is used to quantitatively supply lithium source to the vaporization chamber and generate gaseous lithium source in the vaporization chamber. A carbon source gas supply device is connected to the head of the reaction deposition chamber near the gasification chamber, and a vacuum pump is connected to the tail. The carbon source gas supply device is used to provide a gaseous carbon source to the head of the reaction deposition chamber near the gasification chamber. Under vacuum conditions, inert gas supplied by an inert dilution gas source is used to sequentially guide and push gaseous silicon monoxide and gaseous dopants into the reaction deposition chamber. The deposition and doping of silicon monoxide are completed in sequence. Then, gaseous lithium source and gaseous carbon source are pushed into the reaction deposition chamber in any order or simultaneously to complete lithium replenishment and carbon coating of silicon monoxide, obtaining a solid product. Both lithium replenishment and carbon coating are carried out by CVD, and the atomized carbon is uniformly coated on the surface of silicon monoxide particles during aging. The solid product is then graded and shaped in a graded discharge device to obtain silicon-oxygen anode material.

2. The integrated preparation system for silicon-oxygen anode materials according to claim 1, characterized in that, The vacuum pump is connected to a tail gas recovery device; the reaction deposition chamber is provided with an upper fluid baffle connected to the top and a lower fluid baffle connected to the bottom, the upper fluid baffle and the lower fluid baffle are distributed alternately and a fluid channel is formed between them.

3. A method for preparing silicon-oxygen anode materials using the system described in any one of claims 1 to 2, characterized in that, Includes the following steps: Gas-phase silicon monoxide is prepared in a silicon monoxide generation apparatus. The dopant supply device quantitatively supplies dopant into the vaporization chamber and generates gaseous dopant in the vaporization chamber; The lithium source supply device provides a quantitative amount of lithium source to the gasification chamber and generates gaseous lithium source in the gasification chamber; The carbon source supply device provides a gaseous carbon source to the head of the reaction deposition chamber near the gasification chamber; Under vacuum conditions, inert gas provided by an inert dilution gas source is used to guide and push gaseous silicon monoxide and gaseous dopants into the reaction deposition chamber in sequence. The deposition and doping of silicon monoxide are completed in sequence. Then, gaseous lithium source and gaseous carbon source are pushed into the reaction deposition chamber in any order or simultaneously to complete the lithium replenishment and carbon coating of silicon monoxide and obtain solid products. The solid product is graded and shaped in a grading and discharging device to obtain silicon-oxygen anode material.

4. The method according to claim 3, characterized in that, The raw materials for preparing fumed silica are silicon powder and silica powder, wherein the molar ratio of silicon powder to silica powder is (3~0.5):

1.

5. The method according to claim 3, characterized in that, The dopant is one or more of organophosphorus, inorganic phosphorus, organoboron, and inorganicoboron; the lithium source is one of elemental lithium, lithium oxide, and lithium sulfide.

6. The method according to claim 3, characterized in that, The gaseous carbon source is one or more of methane, acetylene, ethanol, methanol, and acetaldehyde.

7. The method according to claim 3, characterized in that, Before preparing fumed silica, the raw materials, dopants and lithium source of silica are respectively loaded into the silica generating device, the dopant supply device and the lithium source supply device; Start the vacuum pump until the vacuum level inside the silicon monoxide generating device is 10~1000Pa, and adjust the inert gas flow rate; The preset temperature of the vaporization chamber is 1200~1500℃, the preset temperature of the reaction deposition chamber is 600~1100℃, and then the temperature of the silicon monoxide generation device is adjusted to 1300~1800℃ to prepare fumed silicon monoxide.

8. The method according to claim 7, characterized in that, The reaction deposition chamber is preset with two or more temperature zones, and the temperature difference between two adjacent temperature zones is 100~300℃.

9. The method according to claim 3, characterized in that, The reaction time for silicon monoxide doping is 1~1000 min, the reaction time for lithium replenishment is 1~1000 min, and the reaction time for carbon coating is 1~1000 min.

10. The method according to claim 3, characterized in that, The reaction deposition chamber is cooled to 25~100℃ after the reaction is completed.

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