Al / N synergistically coated modified silicon-based composite negative electrode material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of lithium ion battery electrode materials, and particularly relates to an Al / N synergistically-coated modified silicon-based composite negative electrode material as well as a preparation method and application thereof. According to the composite negative electrode material disclosed by the invention, the silicon-based electrode particle material is taken as a core and is coated with the composite layer containing Al and / or N, so that the interface bonding strength can be remarkably improved, and an inter-particle solid electrolyte component with high strength and high ion conduction is constructed. The material is used as a lithium ion battery negative electrode, effectively relieves volume expansion, improves the structural stability and dynamics of the electrode, and is suitable for the field of high-energy-density power batteries. The preparation method disclosed by the invention is simple to operate, cheap in raw materials and easy for large-scale production, has a good application prospect in the field of lithium ion battery electrode materials, and has a relatively high commercial value.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery electrode material technology, and mainly relates to silicon-based anode materials, their preparation methods, and lithium-ion batteries or lithium-ion secondary batteries prepared using silicon-based anodes. Specifically, it relates to an Al / N synergistic coating modified silicon-based composite anode material, its preparation method, and its application. Background Technology

[0002] With the surge in demand for mobile devices, new energy vehicles, and industrial energy storage systems, energy storage technology is undergoing rapid innovation. As the mainstream energy storage carrier, lithium-ion rechargeable batteries, relying on a mature industrial foundation and stable electrochemical performance, have achieved breakthroughs in addressing thermal runaway risks and resource recovery issues through material system improvements and structural design innovations. Compared to traditional battery systems such as lead-acid and nickel-metal hydride batteries, this technology has significant advantages in key parameters such as specific energy, charge / discharge efficiency, and cycle life, and has become a core support for modern energy storage solutions. However, facing the higher requirements for energy storage from emerging scenarios such as renewable energy grid connection and ultra-fast charging, technological breakthroughs are still needed in areas such as electrode material interface stability and environmental friendliness throughout the entire life cycle.

[0003] Currently, commercially available lithium-ion batteries commonly use graphite as the anode material, but its theoretical capacity is significantly limited (only 372 mAh / g), which severely restricts further improvements in battery energy density. Against this backdrop, silicon-based anode materials with ultra-high theoretical capacity are considered a key solution to overcome existing technological bottlenecks. By replacing traditional graphite anodes, they are expected to significantly improve the energy density of lithium-ion batteries.

[0004] Silicon-based anode materials have become a current research hotspot due to their high specific capacity. The theoretical specific capacity of elemental silicon is as high as 4200 mAh / g, and silicon suboxide can reach 2600 mAh / g, far exceeding the 372 mAh / g of commercial graphite anodes. Therefore, based on these combined advantages, developing high-performance silicon-based anode materials with practical value has become an important breakthrough in current lithium-ion battery anode research, and its commercial application is accelerating.

[0005] However, silicon-based materials still face several key technological bottlenecks in practical applications: First, silicon-based materials often exhibit low electrical conductivity and poor lithium-ion diffusion kinetics. Second, silicon-based materials undergo significant volume changes during charge and discharge. This repeated volumetric strain leads to: 1) breakage and pulverization of active material particles; 2) continuous regeneration and thickening of the SEI film; 3) intensified electrolyte decomposition side reactions; and 4) damage to the conductive network, forming "dead zones" of electrochemical deactivation. These synergistic failure mechanisms ultimately cause a sharp decline in electrode capacity, becoming a major obstacle to the commercialization of silicon-based anode materials.

[0006] Due to the aforementioned technological bottlenecks, the proportion of silicon-based materials in current commercial lithium-ion battery anodes is typically controlled within the range of 5-15% (often used in combination with graphite), which severely restricts its potential to improve battery energy density. To achieve large-scale application of silicon-based anodes, two key technological challenges must be overcome: 1) improving kinetic rates; and 2) constructing a stable interface layer that can mitigate expansion and inhibit particle pulverization. Solving these key problems will not only advance the practical application of silicon-based anode materials but also have significant strategic importance for the research and development of next-generation high-energy-density lithium-ion batteries. Summary of the Invention

[0007] This invention relates to an Al / N synergistic coating modified silicon-based composite anode material, its preparation method, and its application in lithium-ion batteries. The composite anode material uses silicon-based material particles as the core, coated with an Al / N composite layer to form a core-shell structure. This invention utilizes Al / N synergy to modify the interface of the silicon-based material particles, significantly improving the interfacial bonding strength and constructing a solid electrolyte composition with high strength and high ion conductivity between particles. As a lithium-ion battery anode, this material effectively alleviates volume expansion, improves conductivity and structural stability, and is suitable for high-energy-density power battery applications.

[0008] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: This invention first provides a method for preparing Al / N synergistic coated modified silicon-based composite anode material. The method utilizes Al / N synergistic compounds capable of forming a dense coating layer to coat and modify silicon-based material particles. After mixing the corresponding Al / N synergistic compounds with silicon-based material particles, the mixture with a certain particle size is subjected to high-temperature heat treatment to obtain a high-performance silicon-based composite anode material.

[0009] The preparation method specifically includes the following steps: Step 1: Dry or wet mix silicon-based materials and precursors containing Al and / or N in a certain proportion to obtain mixture I; Step 2: Place mixture I in a tube furnace and perform high-temperature heat treatment under an inert atmosphere and a certain temperature. Then, allow it to cool naturally to room temperature (25±5℃) to obtain Al / N synergistic coating modified silicon-based composite anode material.

[0010] As a preferred technical solution, the silicon-based material in step 1 is pure silicon or silicon suboxide (SiO2). x ) and one or more of silicon-carbon deposited by CVD, wherein the median particle size D of pure silicon 50 The thickness is 0.05-10 μm, and the silicon suboxide (SiO) is... x The median particle size D of silicon-carbon deposited by CVD 50The thickness is 0.5-20 μm, and the silica suboxide (SiO) is... x The atomic ratio of silicon and oxygen in the silicon oxide is (0.2-0.9):1; or, the silicon suboxide (SiO) x The atomic percentage of silicon in the sample is 61% to 64%, preferably 62.5%.

[0011] As a preferred technical solution, the Al- and / or N-containing precursor in step 1 is one or more of the following: aluminum dihydroxyaminoacetate, aluminum nitrate, aluminum dihydroxymethylacetate, aluminum oxide, aluminum hydroxide, aluminum phosphate, aluminum acetate, aluminum chloride, aluminum carbonate, glycine, urea, melamine, nitric acid, etc.

[0012] As a preferred technical solution, the equipment used in step 1 for mixing is a high-speed ball mill, a V-type mixer, a oscillating mixer, a rotary mixer, a roller ball mill, a horizontal ball mill, a stirred ball mill, a magnetic stirrer, etc. The mixing time is 0.05 to 12 hours, and the mixing speed is 50 to 2000 rpm.

[0013] As a preferred technical solution, in step 1, during wet mixing, the silicon-based material, the precursor containing Al and / or N, and solvent I are mixed and placed on a magnetic stirrer and stirred at room temperature for 1-8 hours (stirring speed of 200-800 r / min); the solvent I is one or more of water, ethanol, NMP (N-methylpyrrolidone), and DMSO.

[0014] As a preferred technical solution, in step 1, during wet mixing, the mass ratio of silicon-based material, Al- and / or N-containing precursor, and solvent I is (15~30):1:(72~90).

[0015] As a preferred technical solution, in step 1, during wet mixing, the mass ratio of silicon-based material, Al- and / or N-containing precursor, and solvent I is (15~18):1:(72~75).

[0016] As a preferred technical solution, in step 1, during dry mixing, the silicon-based material and the precursor containing Al and / or N are mixed and ball-milled at room temperature for 20 min to 3 h.

[0017] As a preferred technical solution, in step 1, during dry mixing, the molar ratio of the silicon-based material to the Al and / or N precursor is 2000:1 to 1:1000.

[0018] As a preferred technical solution, in step 1, during dry mixing, the mass ratio of the silicon-based material to the Al and / or N-containing precursor is (15~30):1.

[0019] As a preferred technical solution, in step 1, during dry mixing, the mass ratio of the silicon-based material to the Al and / or N-containing precursor is (15~18):1.

[0020] As a preferred technical solution, zirconium beads are added as grinding balls during ball milling, and the size of the zirconium beads is 0.1 to 5 mm; the ball milling speed is 200 to 800 r / min.

[0021] As a preferred technical solution, carbon source materials can also be added during mixing in step 1.

[0022] Specifically, the carbon source material is one or more of the following: citric acid, glucose, sucrose, phenolic resin, polyvinyl chloride, polyvinyl alcohol, coal tar pitch, petroleum pitch, and coal-based mesophase pitch.

[0023] As a preferred technical solution, when adding carbon source material, the mass ratio of carbon source material to silicon-based material is 1:(1~100), preferably 1:(1~10).

[0024] As a preferred technical solution, in step 2, the inert atmosphere is formed by one or more of nitrogen, argon, and helium; the gas flow rate under the inert atmosphere is 0.2 to 10 L / min, and the ventilation time is 0.2 to 20 h.

[0025] As a preferred technical solution, when preparing mixture I by wet method, in step 2, before high-temperature heat treatment, mixture I is dried at 50~70℃ for 5~10h.

[0026] As a preferred technical solution, the high-temperature heat treatment in step 2 is high-temperature sintering; the high-temperature heat treatment in step 2 is holding at a temperature of 100℃~1000℃ for 0.2~10h.

[0027] As a preferred technical solution, the high-temperature heat treatment in step 2 is to keep warm at 600℃~1000℃ for 1~5 hours.

[0028] As a preferred technical solution, in step 2, the heating rate during the high-temperature heat treatment is 1 to 10 °C / min.

[0029] Furthermore, the present invention also provides an Al / N synergistic coating modified silicon-based composite anode material prepared by the above method. The composite anode material utilizes Al2O3 / N synergistic uniform coating on the surface of silicon-based particles, while forming a composite coating with a certain mechanical strength on the surface of the composite.

[0030] Furthermore, based on a general inventive concept, the present invention also provides the application of the Al / N synergistic coating modified silicon-based composite anode material in the preparation of lithium-ion batteries or lithium-ion secondary batteries.

[0031] Furthermore, based on a general inventive concept, the present invention also provides a method for preparing lithium-ion batteries or lithium-ion secondary batteries using the Al / N synergistic coating modified silicon-based composite anode material, comprising the following steps: a) Preparation of mixed powder: A certain amount of active material, binder, conductive agent and single-walled carbon nanotubes are placed in a container to obtain mixed powder; b) Preparation of mixed slurry: Mix the mixed powder from step a) with solvent and place it in a container. Put polytetrafluoroethylene magnets into the container and stir at a speed of 100~500 r / min for 6~12 h to make the active material, binder, conductive agent and single-walled carbon nanotubes dispersed evenly to obtain mixed slurry. c) Button cell assembly: The mixed slurry from step b) is coated onto copper foil (current collector) and dried at 50~100℃ for 6~12h to form a button cell electrode disc with a diameter of 12mm; then, using the prepared button cell electrode disc as the working electrode and the lithium metal sheet as the counter electrode, the prepared button cell electrode disc, lithium metal sheet, separator, and electrolyte are assembled into a button cell. The battery model is a CR2032 type button cell.

[0032] Specifically, in step a), the active material is the aforementioned Al / N synergistic coated modified silicon-based composite anode material, or an Al / N synergistic coated modified silicon / graphite composite anode material composed of the aforementioned Al / N synergistic coated modified silicon-based composite anode material and graphite, wherein the mass ratio of the Al / N synergistic coated modified silicon-based composite anode material to graphite in the Al / N synergistic coated modified silicon / graphite composite anode material is 1:(1~10).

[0033] Specifically, the conductive agent in step a) is carbon black (Super-P) or acetylene black.

[0034] Specifically, the binder in step a) is one or more of carboxymethyl cellulose, sodium alginate, ammonium alginate, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid (PPA), lithium-ionized polyacrylic acid (referred to as lithium-ionized PPA or PPALi), and styrene-butadiene rubber (SBR) and polystyrene-butadiene copolymer.

[0035] Specifically, in the mixed powder of step a), the mass ratio of active material, conductive agent, binder and single-walled carbon nanotubes is (80~95):(1~10):(3~10):(0.2~2).

[0036] Specifically, the adhesive is a mixture of carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) in a mass ratio of 1:(1~2), more preferably 1:1.

[0037] Specifically, the solvent is selected from deionized water, ethanol, and NMP.

[0038] Specifically, the mass of the solvent is 1 to 3 times the mass of the mixed powder.

[0039] Specifically, in step c), the separator type is a polypropylene porous separator Celgard2400, and the main component of the electrolyte used in the battery is lithium salt (lithium hexafluorophosphate); preferably, the electrolyte is 1M LiPF6 / EC+DMC (V / V=1:1) with 5wt% fluoroethylene carbonate FEC added.

[0040] Specifically, in step c), the loading of the mixed slurry on the prepared electrode disc is 1~10 mg / cm². 2 .

[0041] Furthermore, based on a general inventive concept, the present invention also provides a lithium-ion battery or lithium-ion secondary battery prepared by the above method.

[0042] Compared with the prior art, the advantages of the present invention are: 1. This invention provides a method for preparing Al / N synergistic coating modified silicon-based composite anode material that is easy to operate, uses inexpensive raw materials, and is easy to scale up. It has good application prospects in the field of lithium-ion battery electrode materials, has high commercial value, and has advantages such as being easy to scale up.

[0043] 2. The silicon-based composite anode material prepared in this invention exhibits significant Al2O3 / N synergistic surface modification characteristics. Al2O3 / N can crosslink with functional groups on the surface of silicon particles and on the binder chains to form a network structure with high stability and rapid ion transport properties, thereby improving interfacial bonding strength and significantly enhancing the solid electrolyte interface strength. As an anode material for lithium-ion batteries, this material effectively alleviates volume expansion, improves conductivity and structural stability, and is suitable for high-energy-density power battery applications. Attached Figure Description

[0044] Figure 1 TEM and EDS elemental distribution diagrams of the Al2O3 / N synergistic coating modified SiOx composite anode material prepared in Example 4; Figure 2 The graphs show the cycling performance of Examples 1, 2, 4, 6 and Comparative Example 1 at 1 A / g. Figure 3The graphs show the cycling performance of Examples 3 and 5, and Comparative Examples 2 and 3 of the present invention at 1 A / g. Detailed Implementation

[0045] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0046] The experimental and testing methods used in the following examples and comparative examples all follow standard operating procedures. Unless otherwise specified, they are all conventional methods. The chemical reagents and materials used in the following examples are all commercially available analytical grade products. Unless otherwise specified, they are all conventional commercial products and can be obtained through commercial channels.

[0047] The following examples and comparative examples use micron-sized silicon suboxide (SiO2). x It is in powder form, produced by Shanghai Xiangtian Nanomaterials Co., Ltd., item number XT-SI0-5U, with a median particle size D. 50 It has a size of 5µm and a silicon atomic percentage of 62.5%.

[0048] The CVD-deposited silicon-carbon was in powder form, purchased from Dongguan Kelude New Energy Technology Co., Ltd., product number MA-EN-AN-0004, with a median particle size D. 50 It has a thickness of 13µm and a silicon content of 35% (mass fraction).

[0049] Glycine (product number A111465-100g) was purchased from Aladdin Biochemical Technology Co., Ltd.

[0050] Aluminum hydroxide (item number 20001060) was purchased from Sinopharm Group Pharmaceutical Co., Ltd.

[0051] Aluminum dihydroxyaminoacetate (item number BD113684-100g) was purchased from Shanghai Bide Pharmaceutical Technology Co., Ltd.

[0052] The zirconium beads (model JZ01-50) were purchased from Wuxi Jiuzhong New Material Technology Co., Ltd., and the size of the zirconium beads is 0.1~5mm.

[0053] The magnetic stir bar (model B30) was purchased from Shanghai Leigu Instrument Co., Ltd.

[0054] The argon gas used in the following examples and comparative examples had a purity of 99.99%. Example 1

[0055] Example 1 provides a wet-process Al2O3 modified SiO2x The preparation method of the composite anode material includes the following specific steps: 1) Add 3g of silicon suboxide (SiO2) x After mixing powder, 0.105g of aluminum hydroxide and 9g of water, a magnetic stir bar was added and the mixture was stirred at 600r / min for 6h on a magnetic stirrer (Gongyi Yuhua Instrument Co., Ltd., model HJ-6A) to obtain mixture A. 2) Place the mixture A from step 1) into a forced-air drying oven and dry at 50℃ for 10 hours. Then place it in a tube furnace, remove the air, and introduce argon gas at a flow rate of 0.5 L / min. Under an atmospheric pressure argon atmosphere, heat to 900℃ (heating rate of 5℃ / min) for atmospheric pressure high-temperature sintering treatment for 2 hours. Then allow it to cool naturally to room temperature (25±5℃) to obtain Al2O3 modified SiO2. x I. Based composite anode material. Example 2

[0056] Example 2 provides a wet-process N-doped synergistic modification of SiO x The preparation method of the composite anode material includes the following specific steps: 1) Add 3g of silicon suboxide (SiO2) x After mixing powder, 0.102g of glycine and 9g of water, a magnetic stir bar was added and the mixture was stirred at 600r / min for 6h on a magnetic stirrer (Gongyi Yuhua Instrument Co., Ltd., model HJ-6A) to obtain mixture B. 2) Place the mixture B from step 1) into a forced-air drying oven and dry at 50℃ for 10 hours. Then place it in a tube furnace, remove the air, and introduce argon gas at a flow rate of 0.5 L / min. Under an atmospheric pressure argon atmosphere, heat to 900℃ (heating rate of 5℃ / min) for atmospheric pressure high-temperature sintering treatment for 2 hours. Then allow it to cool naturally to room temperature (25±5℃) to obtain N-modified SiO. x Composite anode material II. Example 3

[0057] Example 3 provides a dry Al / N synergistic coating modification of SiO x The preparation method of the composite anode material includes the following specific steps: 1) Add 2g of silicon suboxide (SiO2) x The powder and 0.1225g of aluminum dihydroxyaminoacetate were mixed, and 6.3675g of zirconium beads were added. The mixture was then ball-milled in a roller mill at a speed of 500r / min for 30min to obtain mixture C. 2) Place the mixture C from step 1) into a tube furnace, purge the air, and introduce argon gas at a flow rate of 0.5 L / min. In an atmospheric argon atmosphere, heat to 900℃ (heating rate of 5℃ / min) for atmospheric high-temperature sintering treatment for 2 hours, then allow it to cool naturally to room temperature (25±5℃) to obtain Al2O3 / N modified SiO2. x III. Composite anode material. Example 4

[0058] Example 4 provides a wet-process Al / N synergistic coating modification of SiO x The preparation method of the composite anode material includes the following specific steps: 1) Add 2g of silicon suboxide (SiO2) x After mixing powder, 0.1225g of aluminum dihydroxyaminoacetate and 9g of water, a magnetic stir bar was added, and the mixture was stirred at 600r / min for 6h on a magnetic stirrer (Gongyi Yuhua Instrument Co., Ltd., model HJ-6A) to obtain mixture D; 2) Place the mixture D from step 1) into a forced-air drying oven and dry at 50℃ for 10h. Then place it in a tube furnace, remove the air, and introduce argon gas at a flow rate of 0.5L / min. Under an atmospheric pressure argon atmosphere, heat to 900℃ (heating rate of 5℃ / min) for atmospheric pressure high-temperature sintering treatment for 2h. Then allow it to cool naturally to room temperature (25±5℃) to obtain Al2O3 / N modified SiO2. x Base composite anode material IV.

[0059] Figure 1 The TEM and EDS elemental distribution diagrams of the Al2O3 / N synergistic coating modified SiOx composite anode material prepared in Example 4 show that Al and N elements are uniformly distributed on the surface of the subsilicon particles, proving the feasibility of this coating method. Example 5

[0060] Example 5 provides a method for preparing a wet-process Al / N synergistic coating modified CVD deposited silicon-carbon based composite anode material, the specific steps of which are as follows: 1) Mix 2g of CVD-deposited silicon carbide powder, 0.1225g of aluminum dihydroxyaminoacetate and 9g of water, add a magnetic stir bar, and stir on a magnetic stirrer (Gongyi Yuhua Instrument Co., Ltd., model HJ-6A) at a speed of 600r / min for 6h to obtain mixture E; 2) Place the mixture E from step 1) into a forced-air drying oven and dry it at 50℃ for 10h. Then place it into a tube furnace, remove the air, and introduce argon gas at a flow rate of 0.5L / min. In an atmospheric pressure argon atmosphere, heat the mixture to 900℃ (heating rate of 5℃ / min) for atmospheric pressure high-temperature sintering treatment for 2h. Then allow it to cool naturally to room temperature (25±5℃) to obtain Al2O3 / N modified CVD deposited silicon-carbon based composite anode material V. Example 6

[0061] Example 6 provides a method for synergistically achieving Al / N modification of SiO2 through wet premixing and in-situ electrochemical processes. x The preparation method of the composite anode material includes the following specific steps: 2g of silicon suboxide (SiO) x 0.1225 g of aluminum dihydroxyaminoacetate powder and 9 g of water were mixed, and then a magnetic stir bar was added. The mixture was stirred at 600 r / min for 6 h on a magnetic stirrer (Gongyi Yuhua Instrument Co., Ltd., model HJ-6A) to obtain modified SiO2. x VI. Composite anode material.

[0062] Comparative Example 1 Raw, untreated micron-sized silicon suboxide (SiO2) x The powder is used directly as the negative electrode material.

[0063] Comparative Example 2 Raw, untreated micron-sized silicon suboxide (SiO2) x The powder was placed in a tube furnace, air was removed, and argon gas was introduced at a flow rate of 0.5 L / min. Under atmospheric pressure and argon atmosphere, the temperature was increased at a rate of 5 °C / min until it reached 900 °C. This temperature was then held for 2 hours for atmospheric pressure calcination, followed by natural cooling to room temperature (25 ± 5 °C) to obtain heat-treated SiO₂. x Material VII.

[0064] Comparative Example 3 Raw, untreated CVD-deposited silicon-carbon powder is used directly as the anode material.

[0065] Performance testing The products prepared in Examples 1-6 and Comparative Examples 1-3 were assembled into batteries and their electrochemical performance was tested (the test methods are referenced in Wang, Haolin, et al. "What Is the Real Origin of Single-Walled Carbon Nanotubes for the Performance Enhancement of Si-Based Anodes?" Journal of the American Chemical Society 2024, 146(25), 17041-17053). The specific methods are as follows: a) Preparation of mixed powder: The active material (the product prepared in Examples 1-6 or Comparative Examples 1, 2, 3), binder (sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR)), carbon black Super P (carbon-based conductive agent, purchased from Shenzhen Kejing Zhida Technology Co., Ltd., brand name CAS 1333-86-4), and single-walled carbon nanotubes (purchased from Dongguan Kelude New Energy Technology Co., Ltd., product name MA-EN-CO-0010) were mixed in a mass ratio of 90:5:4:1 to obtain mixed powder; The mass ratio of CMC to SBR is 1:1. The CMC model is MAC500LC and the SBR model is JSR TRD104A, both of which were purchased from Shenzhen Kejing Zhida Technology Co., Ltd. b) Preparation of the mixed slurry: The mixed powder from step a) is added to the solvent (deionized water), placed in a mixing container and mixed evenly. The mass ratio of the mixed powder to the solvent is 1:2.5. Then, a polytetrafluoroethylene (PTFE) magnet is placed in the mixing container and stirred at a speed of 400 r / min for 10 h to disperse the active material, binder (CMC+SBR), carbon black Super-P, and single-walled carbon nanotubes evenly, thus obtaining the mixed slurry. c) Button cell assembly and performance testing: The mixed slurry from step b) was coated onto copper foil (current collector) and vacuum dried at 80°C for 12 h to obtain a loading of 1.5 mg / cm³. 2 The negative electrode sheet is then prepared; then a punching machine or a slicer is used to make the prepared negative electrode sheet into a button electrode disc with a diameter of 12 mm; In a glove box filled with argon gas (H2O / O2 < 0.1 ppm), using a CR2032 coin cell model, the prepared coin cell electrode discs (negative electrode) and a lithium metal sheet (as counter electrode) were assembled into a coin cell. Specifically: A 15.8 mm diameter lithium metal sheet was used as the counter electrode, and a prepared button electrode disc (negative electrode) was used as the working electrode. A Celgard 2400 polypropylene porous membrane was used as the isolation layer. The electrolyte (Suzhou Duoduo Chemical Technology Co., Ltd., catalog number LB-007) was 1M LiPF6 / EC+DMC (V / V=1:1) with 5 wt% fluoroethylene carbonate FEC added. The negative electrode shell, negative electrode sheet, electrolyte-soaked separator, lithium metal sheet (counter electrode), gasket, spring sheet, and positive electrode shell are stacked in sequence and finally sealed under 8 MPa pressure using a sealing machine to produce a coin cell (CR2032 type) for performance testing.

[0066] The cyclic stability of the electrode material was evaluated using a constant current charge-discharge method. The specific test procedure was as follows: First, three activation cycles were performed at a low current density of 0.1 A / g to fully activate the electrode material; then, the current density was increased to 1 A / g for long-term cyclic testing, with the charge-discharge voltage window controlled between 0.01 and 2 V (vs. Li). + Within the range of / Li), the cycling performance of the material under high current density was examined.

[0067] Following the battery assembly and testing methods described above, the cycle performance of the negative electrode materials prepared in Examples 1-6 of this invention and the negative electrode materials in Comparative Examples 1-3 was tested, and the performance results are shown in Table 1 and... Figure 2-3 As shown.

[0068] Table 1. Performance test results of Examples 1-6 and Comparative Examples 1-3.

[0069]

[0070] From Table 1 and Figure 2 , 3 As can be seen, the doped silicon-based anode materials obtained in Examples 1-6 exhibit superior cycling performance, while Comparative Examples 1-2 show a significant performance decline. Specifically, Examples 1, 2, and 4 have capacities of 1150.5, 1167.7, and 1230.4 mAh / g after 200 cycles at 1 A / g, respectively, while Comparative Example 1 shows a capacity of only 823.4 mAh / g after 200 cycles, demonstrating a significant performance decrease. Examples 3, 5, Comparative Examples 2, and 3 have capacities of 1159.7, 1101.1, 719.6, and 625.5 mAh / g after 250 cycles at 1 A / g, respectively. These data indicate that doping and modifying silicon-based anodes with Al-containing, nitrogen-containing, or a combination of both precursors can effectively improve their lithium storage performance.

[0071] In summary, the Al / N synergistic coating modified SiO prepared by this invention...x Composite anode materials, used as anode materials for lithium batteries, utilize a composite layer of coated metallic and non-metallic elements to form a core-shell structure, enabling them to withstand SiO₂. x The interface is modified to improve interfacial bonding strength, significantly enhance the solid electrolyte interface (SEI) strength, and optimize ion diffusion pathways. As a negative electrode for lithium-ion batteries, this material effectively alleviates volume expansion and improves conductivity and structural stability.

[0072] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an Al / N synergistic coating modified silicon-based composite anode material, characterized in that, Includes the following steps: 1) Mixture I is obtained by dry or wet mixing of silicon-based materials and precursors containing Al and / or N in a certain proportion; 2) Mixture I was placed in a tube furnace and subjected to high-temperature heat treatment under an inert atmosphere and a certain temperature. Then it was naturally cooled to room temperature to obtain Al / N synergistic coating modified silicon-based composite anode material.

2. The preparation method according to claim 1, characterized in that, In step 1), the silicon-based material is one or more of pure silicon, silicon suboxide, and CVD-deposited silicon-carbon, wherein the median particle size D of pure silicon is... 50 The median particle size D of subsilica and CVD-deposited silicon-carbon is 0.05-10 μm. 50 The silicon suboxide has a particle size of 0.5-20 μm and an atomic ratio of silicon to oxygen of (0.2-0.9):1; or, the silicon suboxide has an atomic percentage of 61%-64%. In step 1), the Al- and / or N-containing precursor is one or more of the following: aluminum dihydroxyaminoacetate, aluminum nitrate, aluminum dihydroxymethylacetate, aluminum oxide, aluminum hydroxide, aluminum phosphate, aluminum acetate, aluminum chloride, aluminum carbonate, glycine, urea, melamine, lithium nitrate, etc.

3. The preparation method according to claim 1, characterized in that, In step 1), during wet mixing, the silicon-based material, the Al- and / or N-containing precursor, and solvent I are mixed and stirred at room temperature for 1 to 8 hours; the solvent I is one or more of water, ethanol, NMP, and DMSO. In step 1), during wet mixing, the mass ratio of silicon-based material, Al- and / or N-containing precursor, and solvent I is (15~30):1:(72~90).

4. The preparation method according to claim 1, characterized in that, In step 1), during dry mixing, the silicon-based material and the precursor containing Al and / or N are mixed and ball-milled at room temperature for 20 min to 3 h. In step 1), during dry mixing, the molar ratio of the silicon-based material to the Al and / or N precursor is 2000:1 to 1:1000.

5. The preparation method according to claim 1, characterized in that, In step 1), carbon source materials can also be added during mixing; The carbon source material is one or more of the following: citric acid, glucose, sucrose, phenolic resin, polyvinyl chloride, polyvinyl alcohol, coal tar pitch, petroleum pitch, and coal-based mesophase pitch. When adding carbon source material, the mass ratio of carbon source material to silicon-based material is 1:(1~100).

6. The preparation method according to claim 1, characterized in that, In step 2), the inert atmosphere is formed by one or more of nitrogen, argon, and helium; the gas flow rate under the inert atmosphere is 0.2 to 10 L / min, and the ventilation time is 0.2 to 20 h.

7. The preparation method according to claim 1, characterized in that, The high-temperature heat treatment mentioned in step 2) is high-temperature sintering; in step 2), the high-temperature heat treatment is holding at a temperature of 100℃~1000℃ for 0.2-10 h.

8. Al / N synergistic coating modified silicon-based composite anode material prepared by any of the methods described in claims 1 to 7.

9. The application of the Al / N synergistic coating modified silicon-based composite anode material according to claim 8 in the preparation of lithium-ion batteries or lithium-ion secondary batteries.

10. A method for preparing a lithium-ion battery or a lithium-ion secondary battery using the Al / N synergistic coating modified silicon-based composite anode material as described in claim 8, comprising the following steps: a) Preparation of mixed powder: A certain amount of active material, binder, conductive agent and single-walled carbon nanotubes are placed in a container to obtain mixed powder; b) Preparation of mixed slurry: Mix the mixed powder from step a) with solvent and place it in a container. Stir at a speed of 100~500 r / min for 6~12 h to disperse the active material, binder, conductive agent and single-walled carbon nanotubes evenly to obtain mixed slurry. c) Button cell assembly: The mixed slurry from step b) is coated onto copper foil (current collector) and dried at 50~100℃ for 6~12h to form a button cell electrode disc with a diameter of 12mm; then, using the prepared button cell electrode disc as the working electrode and the lithium metal sheet as the counter electrode, the prepared button cell electrode disc, lithium metal sheet, separator, and electrolyte are assembled into a button cell. The battery model is a CR2032 type button cell. In step a), the active material is the Al / N synergistic coated modified silicon-based composite anode material as described in claim 8, or an Al / N synergistic coated modified silicon / graphite composite anode material composed of the Al / N synergistic coated modified silicon-based composite anode material as described in claim 8 and graphite, wherein the mass ratio of the Al / N synergistic coated modified silicon-based composite anode material to graphite in the Al / N synergistic coated modified silicon / graphite composite anode material is 1:(1~10). In step a), the conductive agent is carbon black (Super-P) or acetylene black; The binder in step a) is one or more of carboxymethyl cellulose, sodium alginate, ammonium alginate, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, lithium-ionized polyacrylic acid, and styrene-butadiene rubber and polystyrene-butadiene copolymer.

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