Nitrogen-doped integrated micron-sized silicon-oxygen anode materials, their preparation methods and applications

Abstract

This invention relates to a nitrogen-doped integrated micron-sized silicon-oxygen anode material, its preparation method, and its application. The preparation method includes the following steps: dissolving a carbon source in water, then mixing it with silicon suboxide and a nitrogen source to obtain a mixed slurry; coating the mixed slurry onto a current collector, drying the current collector to obtain an electrode sheet; and carbonizing the electrode sheet to co-carbonize the carbon and nitrogen sources to form a nitrogen-doped three-dimensional carbon framework. This carbon framework simultaneously acts as a conductive agent, binder, and volume buffer framework, resulting in an integrated nitrogen-doped silicon-oxygen anode. By optimizing the electrode microstructure through nitrogen doping and promoting uniform lithium distribution and conversion, irreversible lithium loss is effectively suppressed. Simultaneously, this method, through the synergistic effect of the integrated carbon framework and nitrogen doping, effectively alleviates the volume expansion of the silicon-oxygen anode, promotes uniform lithium distribution and reversibility, suppresses irreversible lithium loss, and significantly improves cycle stability and rate performance.

Description

Technical Field

[0001] This invention relates to the field of electrode materials technology, and in particular to a nitrogen-doped integrated micron-sized silicon-oxygen anode material, its preparation method, and its application. Background Technology

[0002] Silicon-based anodes possess extremely high theoretical specific capacity (Li). 3.75 The specific capacity of Si is 3579 mAh g. -1 With a suitable lithiation platform (approximately 0.4V) and the ability to effectively suppress lithium dendrite growth and reduce safety risks such as internal short circuits in batteries, it is widely considered an ideal candidate material for the next generation of high-performance lithium-ion battery anodes.

[0003] However, during the alloying / dealloying reaction, silicon particles undergo significant volume expansion and contraction (approximately 280%), leading to continuous degradation of silicon-based materials and battery capacity decay. Furthermore, the drastic volume changes pose challenges to the stability and integrity of the battery structure. In addition, silicon-based anodes also suffer from key bottlenecks such as poor intrinsic conductivity, sluggish reaction kinetics, and side reactions with the electrolyte.

[0004] Specifically, capacity decay essentially stems from the continuous loss of active material. During delithiation, some of the lithium-ionized active silicon cannot be fully recovered, thus transforming into deactivated silicon. This deactivated silicon can be divided into two categories:

[0005] Irreversible deactivation components: mainly include electrochemically irreversible substances (such as lithium silicates generated by the reaction of the surface oxide layer with the electrolyte), silicon particles that detach from the electrode due to volume expansion, and silicon particles wrapped by a non-conductive solid electrolyte interface (SEI) layer.

[0006] Reversible deactivation components: mainly related to the slow kinetics of alloying / dealloying reactions and high interfacial impedance. Due to high electronic and ionic resistance, significant electrode polarization leads to a lithium concentration gradient within the particles. This is particularly true in Li... 3.75 During the delithiation process of Si, although the surface lithium is depleted, there may still be lithium inside as Li. x The Si form is "captured" and cannot participate in subsequent reactions.

[0007] To address the aforementioned issues, researchers have conducted in-depth studies across multiple dimensions, including structural modification, binder optimization, electrolyte design, and interface engineering. Among these, interface engineering, as a key modification strategy, can significantly improve the overall electrochemical performance of silicon-based anodes (especially silicon-oxygen anodes) by designing and controlling the physicochemical properties of the interface between electrode materials and electrolytes. However, most current research on interface engineering focuses on solving single issues such as volume expansion or lithium-ion transport kinetics. Summary of the Invention

[0008] Therefore, the purpose of this invention is to provide a nitrogen-doped integrated micron-sized silicon-oxygen anode material, its preparation method, and its application. By optimizing the electrode microstructure through nitrogen doping and promoting the uniform distribution and conversion of lithium, irreversible lithium loss is effectively suppressed. Simultaneously, the integrated electrode material prepared by this method provides a uniform conductive and mass transfer path, demonstrating a highly efficient effect in solving the volume expansion problem of micron-sized silicon.

[0009] First aspect: A method for preparing a nitrogen-doped integrated micron-sized silicon-oxygen anode material includes the following steps: The carbon source is dissolved in water and then mixed with silicon suboxide and a nitrogen source to obtain a mixed slurry; The mixed slurry is coated onto the current collector, and the current collector is dried to obtain the electrode sheet; The electrode is carbonized to obtain the nitrogen-doped integrated micron silicon-oxygen anode material. The silicon suboxide has a particle size of 3-10 μm, the carbon source includes at least one of starch and lithium polyacrylate (PAALi), and the nitrogen source includes at least one of melamine and urea.

[0010] Compared with the prior art, the present invention has the following advantages and technical effects: 1. This invention prepares an integrated electrode in which the carbon source acts as both a conductive agent and a binder after carbonization. This allows for the construction of a physical composite framework at the electrode scale, enabling a uniform distribution of point-to-point stress on individual silicon particles at the electrode scale. Simultaneously, the three-dimensional interconnect framework provides a uniform conductive and mass transfer path, demonstrating a highly efficient effect in solving the volume expansion problem of micron-sized silicon.

[0011] 2. During the integrated electrode fabrication, nitrogen sites are uniformly distributed, and this uniform distribution of nitrogen sites promotes the formation of lithium silicate and amorphous Li. x The uniform formation of the Si phase promotes a more uniform distribution of lithium. This helps alleviate internal stress, prevents continuous exposure of the active surface, and reduces irreversible lithium loss. Furthermore, nitrogen doping also improves the Li-Si bond structure by extending the Li-Si bond. + The uniform flux distribution and accelerated delithiation reaction improve lithium conversion efficiency and minimize the accumulation of inactive lithium. By suppressing irreversible silicon accumulation and promoting the transformation of reversible active silicon, the nitrogen doping strategy effectively enhances the capacity and cycle stability of the integrated electrode.

[0012] 3. This invention provides new insights into optimizing integrated silicon-based anodes, deepening the understanding of capacity loss electrochemical behavior, and offers potential solutions for the practical application of micron-scale silicon in lithium-ion batteries.

[0013] 4. This invention limits the silicon suboxide particle size to 3-10 μm, more preferably 3-5 μm. This particle size is a preferred option that balances electrochemical performance and structural stability. If the particle size is too large, high stress is easily generated during lithiation, leading to particle breakage and pulverization, forming irreversible deactivated silicon and exacerbating "lithium capture". If the particle size is too small, it will bring many problems in practical applications: the high specific surface area leads to a large amount of active lithium being consumed in the SEI film, reducing the initial coulombic efficiency; nanoparticles are prone to agglomeration and dispersion, resulting in uneven coating; low tap density limits electrode compaction density, reduces volumetric energy density, and increases preparation cost, which is not conducive to large-scale production. Therefore, the moderate particle size of 3-5 μm can avoid the above defects and balance high initial efficiency, long cycle life, and good process adaptability.

[0014] As a preferred embodiment, the mass ratio of silicon suboxide to the nitrogen source is 1:0.05~1. More preferably, it is 1:0.05~0.2, and even more preferably, it is 1:0.1. If the nitrogen source ratio is too low, the nitrogen doping amount in the carbon framework is insufficient, resulting in few active sites and limited improvement in conductivity and interface impedance, failing to effectively promote uniform lithium distribution and suppress irreversible lithium loss. If the nitrogen source ratio is too high, excessive nitrogen will damage the carbon framework structure during carbonization, leading to slagging and cracking on the electrode surface. Furthermore, excessive nitrogen doping may form excessive pyridine nitrogen and other defects, thus reducing structural stability.

[0015] As a preferred embodiment, the mass ratio of silicon suboxide to the carbon source is 1 to 2:1. If the proportion of carbon source is too high, too much carbon skeleton remains after carbonization. Although this can provide a better conductive network and buffer space, it will reduce the proportion of active material in the electrode, resulting in a decrease in overall specific capacity. If the proportion of carbon source is too low, the carbon layer formed by carbonization is insufficient to completely cover the silicon suboxide particles, resulting in poor conductivity and inability to effectively buffer volume expansion. During cycling, the particles are prone to pulverization and detachment.

[0016] As a preferred embodiment, the carbon source, silicon suboxide, and nitrogen source are mixed by stirring at a speed of 250-450 r / min for 3-6 h. More preferably, the mixing speed is 280-350 r / min for 4-6 h.

[0017] As a preferred embodiment, the carbonization temperature is 300~700℃ and the time is 0.1~24h. More preferably, the carbonization temperature is 500~600℃ and the carbonization time is 50min~500min. If the carbonization temperature is too low or the time is too short, the carbon and nitrogen sources will not pyrolyze sufficiently, resulting in poor conductivity, a loose structure, and incomplete nitrogen doping of the carbon layer, which cannot effectively buffer volume expansion. If the carbonization temperature is too high or the time is too long, the carbon skeleton will become over-graphitized and brittle, and nitrogen will easily be lost at high temperatures, reducing the doping effect.

[0018] As a preferred embodiment, the coating thickness of the mixed slurry on the current collector is 15~25 μm. More preferably, the coating thickness is 15~18 μm.

[0019] If the coating is too thick, the increased ion / electron transport path leads to intensified polarization and decreased rate performance. At the same time, the internal stress generated by the volume expansion of the silicon-oxygen anode during cycling can easily cause the coating to crack and pulverize, and the shedding of active material accelerates capacity decay. If the coating is too thin, the active material loading per unit area is low, the overall energy density of the battery decreases, and the proportion of non-active materials such as current collectors increases, increasing manufacturing costs.

[0020] As a preferred embodiment, the drying of the current collector includes the following steps: first, drying in a forced-air drying oven at 60~80℃ for 0.1~1h, followed by drying in a vacuum drying oven at 80~120℃ for more than 12h.

[0021] As a preferred embodiment, the current collector comprises at least one of single-sided copper foil and porous copper foil.

[0022] The second aspect: A nitrogen-doped integrated micron-sized silicon-oxygen anode material is prepared by the preparation method described in the first aspect.

[0023] Third aspect: A lithium-ion battery comprising the nitrogen-doped integrated micron-sized silicon-oxygen anode material as described in the second aspect. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the fabrication process of nitrogen-doped integrated micron-sized silicon-oxygen anode material.

[0025] Figure 2 The graphs show the FI-TR measurement results of the electrode materials in Examples 1-5 and Comparative Example 1.

[0026] Figure 3 These are elemental content analysis charts of the electrode materials in Examples 1-4 and Comparative Example 1.

[0027] Figure 4 These are XPS images of the electrode materials in Examples 1-3 and Comparative Example 1.

[0028] Figure 5 The graphs show the electrochemical cycling performance of batteries made from the electrode materials of Examples 1-5 and Comparative Example 1.

[0029] Figure 6 The graphs show the electrochemical rate performance of batteries made from the electrode materials of Examples 1-5 and Comparative Example 1.

[0030] Figure 7 The graph shows the electrochemical capacity retention rate of the electrode materials of Examples 1-5 and Comparative Example 1 after they were prepared into batteries.

[0031] Figure 8 The graphs show the electrochemical cycling performance of batteries made from the electrode materials of Examples 2 and Comparative Examples 1-2.

[0032] Figure 9 The graphs show the electrochemical rate performance of batteries made from the electrode materials of Examples 2 and Comparative Examples 1-2. Detailed Implementation

[0033] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0034] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0035] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0036] A method for preparing a nitrogen-doped integrated micron-sized silicon-oxygen anode material includes the following steps: The carbon source is dissolved in water and then mixed with silicon suboxide and a nitrogen source to obtain a mixed slurry; The mixed slurry is coated onto the current collector, and then the current collector is dried to obtain the electrode sheet; The electrode sheet is carbonized to obtain a nitrogen-doped integrated micron silicon-oxygen anode material. The silicon suboxide has a particle size of 3~10μm, the carbon source includes at least one of starch and lithium polyacrylate (PAALi), the nitrogen source includes at least one of melamine and urea, and the current collector includes at least one of single-sided copper foil and porous copper foil.

[0037] The mass ratio of silicon suboxide to nitrogen source is 1:0.05~1. More preferably, it is 1:0.05~0.2, and even more preferably, it is 1:0.1.

[0038] The mass ratio of silicon suboxide to carbon source is 1~2:1.

[0039] The carbon source, silicon suboxide, and nitrogen source are mixed by stirring at a speed of 250–450 r / min for 3–6 h. More preferably, the mixing speed is 280–350 r / min for 4–6 h. Specifically, the stirring speed can be 280 r / min, 290 r / min, 300 r / min, 310 r / min, 320 r / min, 330 r / min, 340 r / min, or 350 r / min; and the stirring time can be 4 h, 5 h, or 6 h.

[0040] The carbonization temperature is 300~700℃, and the time is 0.1~24h. More preferably, the carbonization temperature is 500~600℃, and the carbonization time is 50min~500min. Specifically, the carbonization temperature can be 300℃, 400℃, or 500℃; and the carbonization time can be 50min, 100min, 200min, 300min, 400min, or 500min.

[0041] The coating thickness of the mixed slurry on the current collector is 15~25 μm. More preferably, the coating thickness is 15~18 μm.

[0042] The drying of the current collector includes the following steps: first, drying in a forced-air drying oven at 60~80℃ for 0.1~1h, followed by drying in a vacuum drying oven at 80~120℃ for more than 12h.

[0043] In this embodiment of the invention, room temperature refers to 25±2℃.

[0044] In some embodiments, the carbon source needs to be treated, such as starch needing to be gelatinized at a temperature of 80°C for 30 minutes.

[0045] In this embodiment of the invention, starch is selected as the carbon source because starch is a natural polysaccharide whose molecules are formed by glucose units linked by glycosidic bonds to form long chain structures, exhibiting linear or branched characteristics. Its advantage as a primary binder lies in its elemental composition, containing only C, H, and O elements, without other impurities, making it suitable as a doping matrix. Furthermore, its abundant oxygen-containing functional groups can interact with SiO₂. x The interactions form a stable complex structure. Furthermore, starch can undergo gelatinization in aqueous solution to form a viscous colloid, making it even more suitable as a binder.

[0046] A lithium-ion battery includes a nitrogen-doped integrated micron-sized silicon-oxygen anode material, a cathode, a separator, and an electrolyte.

[0047] The positive electrode is preferably at least one of lithium metal sheet, lithium foil, NCM811 positive electrode, NCM622 positive electrode, and lithium iron phosphate positive electrode. The separator is preferably at least one of PP and PE. The electrolyte also includes cations corresponding to the active material of the positive electrode.

[0048] Example 1 like Figure 1 As shown, a method for preparing a nitrogen-doped integrated micron-sized silicon-oxygen anode material includes the following steps: S1: Gelatinize 1g of starch at 80℃ for 30min, then add 1g of silica with a particle size of 5μm and 0.05g of melamine, and mix with magnetic stirring at room temperature at a speed of 350r / min for 5h to obtain a mixed slurry.

[0049] The mixed slurry was coated onto a single-sided copper foil with a coating thickness of 15~18µm. After coating, the single-sided copper foil was dried in a 60℃ forced-air oven for 30min, and then transferred to a vacuum dryer at 80℃ for more than 12h to obtain an uncarbonized micron-sized silicon suboxide anode containing non-metallic nitrogen elements.

[0050] S2: Cut the dried electrode sheet into round pieces with a diameter of 12mm using a cutting machine. Clamp the cut electrode sheet with two battery pads and paper clips to complete the preparation of the carbonized electrode sheet.

[0051] S3: Place the processed electrode sheet into a tube furnace, purge it with argon gas, raise the temperature to 500℃ at a heating rate of 1℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature to obtain nitrogen-doped integrated micron silicon-oxygen anode material.

[0052] Example 2 A method for preparing a nitrogen-doped integrated micron-sized silicon-oxygen anode material includes the following steps: S1: Gelatinize 1g of starch at 80℃ for 30min, then add 1g of silica with a particle size of 5μm and 0.10g of melamine, and mix with magnetic stirring at room temperature at a speed of 350r / min for 5h to obtain a mixed slurry.

[0053] The mixed slurry was coated onto a single-sided copper foil with a coating thickness of 15~18µm. After coating, the single-sided copper foil was dried in a 60℃ forced-air oven for 30min, and then transferred to a vacuum dryer at 80℃ for more than 12h to obtain an uncarbonized micron-sized silicon suboxide anode containing non-metallic nitrogen elements.

[0054] S2: Cut the dried electrode sheet into round pieces with a diameter of 12mm using a cutting machine. Clamp the cut electrode sheet with two battery pads and paper clips to complete the preparation of the carbonized electrode sheet.

[0055] S3: Place the processed electrode sheet into a tube furnace, purge it with argon gas, raise the temperature to 500℃ at a heating rate of 1℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature to obtain nitrogen-doped integrated micron silicon-oxygen anode material.

[0056] Example 3 A method for preparing a nitrogen-doped integrated micron-sized silicon-oxygen anode material includes the following steps: S1: Gelatinize 1g of starch at 80℃ for 30min, then add 1g of silica with a particle size of 5μm and 0.20g of melamine, and mix with magnetic stirring at room temperature at a speed of 350r / min for 5h to obtain a mixed slurry.

[0057] The mixed slurry was coated onto a single-sided copper foil with a coating thickness of 15~18µm. After coating, the single-sided copper foil was dried in a 60℃ forced-air oven for 30min, and then transferred to a vacuum dryer at 80℃ for more than 12h to obtain an uncarbonized micron-sized silicon suboxide anode containing non-metallic nitrogen elements.

[0058] S2: Cut the dried electrode sheet into round pieces with a diameter of 12mm using a cutting machine. Clamp the cut electrode sheet with two battery pads and paper clips to complete the preparation of the carbonized electrode sheet.

[0059] S3: Place the processed electrode sheet into a tube furnace, purge it with argon gas, raise the temperature to 500℃ at a heating rate of 1℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature to obtain nitrogen-doped integrated micron silicon-oxygen anode material.

[0060] Example 4 A method for preparing a nitrogen-doped integrated micron-sized silicon-oxygen anode material includes the following steps: S1: Gelatinize 1g of starch at 80℃ for 30min, then add 1g of silica with a particle size of 5μm and 0.70g of melamine, and mix with magnetic stirring at room temperature at a speed of 350r / min for 5h to obtain a mixed slurry.

[0061] The mixed slurry was coated onto a single-sided copper foil with a coating thickness of 15~18µm. After coating, the single-sided copper foil was dried in a 60℃ forced-air oven for 30min, and then transferred to a vacuum dryer at 80℃ for more than 12h to obtain an uncarbonized micron-sized silicon suboxide anode containing non-metallic nitrogen elements.

[0062] S2: Cut the dried electrode sheet into round pieces with a diameter of 12mm using a cutting machine. Clamp the cut electrode sheet with two battery pads and paper clips to complete the preparation of the carbonized electrode sheet.

[0063] S3: Place the processed electrode sheet into a tube furnace, purge it with argon gas, raise the temperature to 500℃ at a heating rate of 1℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature to obtain nitrogen-doped integrated micron silicon-oxygen anode material.

[0064] Example 5 A method for preparing a nitrogen-doped integrated micron-sized silicon-oxygen anode material includes the following steps: S1: Gelatinize 1g of starch at 80℃ for 30min, then add 1g of silica with a particle size of 5μm and 1.00g of melamine, and mix with magnetic stirring at room temperature at a speed of 350r / min for 5h to obtain a mixed slurry.

[0065] The mixed slurry was coated onto a single-sided copper foil with a coating thickness of 15~18µm. After coating, the single-sided copper foil was dried in a 60℃ forced-air oven for 30min, and then transferred to a vacuum dryer at 80℃ for more than 12h to obtain an uncarbonized micron-sized silicon suboxide anode containing non-metallic nitrogen elements.

[0066] S2: Cut the dried electrode sheet into round pieces with a diameter of 12mm using a cutting machine. Clamp the cut electrode sheet with two battery pads and paper clips to complete the preparation of the carbonized electrode sheet.

[0067] S3: Place the processed electrode sheet into a tube furnace, purge it with argon gas, raise the temperature to 500℃ at a heating rate of 1℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature to obtain nitrogen-doped integrated micron silicon-oxygen anode material.

[0068] Example 6 A method for preparing a nitrogen-doped integrated micron-sized silicon-oxygen anode material includes the following steps: S1: Gelatinize 1g of starch at 80℃ for 30min, then add 1g of silica with a particle size of 5μm and 0.1g of urea, and mix with magnetic stirring at room temperature at a speed of 350r / min for 5h to obtain a mixed slurry.

[0069] The mixed slurry was coated onto a single-sided copper foil with a coating thickness of 15~18µm. After coating, the single-sided copper foil was dried in a 60℃ forced-air oven for 30min, and then transferred to a vacuum dryer at 80℃ for more than 12h to obtain an uncarbonized micron-sized silicon suboxide anode containing non-metallic nitrogen elements.

[0070] S2: Cut the dried electrode sheet into round pieces with a diameter of 12mm using a cutting machine. Clamp the cut electrode sheet with two battery pads and paper clips to complete the preparation of the carbonized electrode sheet.

[0071] S3: Place the processed electrode sheet into a tube furnace, purge it with argon gas, raise the temperature to 500℃ at a heating rate of 1℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature to obtain nitrogen-doped integrated micron silicon-oxygen anode material.

[0072] Comparative Example 1 S1: Gelatinize 1g of starch at 80℃ for 30min, then add 1g of silica with a particle size of 5μm and mix with magnetic stirring at room temperature at a speed of 350r / min for 5h to obtain a mixed slurry.

[0073] The mixed slurry was coated onto a single-sided copper foil with a coating thickness of 15~18µm. After coating, the single-sided copper foil was dried in a 60℃ forced-air oven for 30min, and then transferred to a vacuum dryer at 80℃ for more than 12h to obtain an uncarbonized micron-sized silicon suboxide anode sheet.

[0074] S2: Cut the dried electrode sheet into round pieces with a diameter of 12mm using a cutting machine. Clamp the cut electrode sheet with two battery pads and paper clips to complete the preparation of the carbonized electrode sheet.

[0075] S3: Place the processed electrode sheet into a tube furnace, purge it with argon gas, raise the temperature to 500℃ at a heating rate of 1℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature to obtain nitrogen-doped integrated micron silicon-oxygen anode material.

[0076] Comparative Example 2 S1: Disperse silica, PAALi and Super-P in deionized water at a mass ratio of 95:2.5:2.5 and mix them at room temperature using magnetic stirring at a speed of 350 r / min for 5 h to obtain a mixed slurry.

[0077] The mixed slurry was coated onto a single-sided copper foil with a coating thickness of 15~18µm. After coating, the single-sided copper foil was dried in a 60℃ forced-air oven for 30min, and then transferred to a vacuum dryer at 80℃ for more than 12h to obtain a micron-sized silicon suboxide anode sheet.

[0078] S2: Cut the dried electrode sheet into round pieces with a diameter of 12mm using a cutting machine.

[0079] The micron-sized silicon-oxygen anode materials prepared in Examples 1-5 and Comparative Example 1 were subjected to Fourier transform infrared spectroscopy, and the micron-sized silicon-oxygen anode materials prepared in Examples 1-4 and Comparative Example 1 were subjected to XPS spectroscopy. The XPS spectroscopy results were then subjected to elemental analysis.

[0080] like Figure 2 As shown, Fourier transform infrared spectroscopy (FT-IR) was used to monitor changes in the functional groups of the mixture to verify the chemical interactions between the materials. The results indicate that at 2493.6 cm⁻¹... -1 Signals of hydrogen bonding between -NH2 groups and O atoms were observed between starch and melamine; simultaneously, SiO xThe interaction between the silanol groups (Si-OH) on the particles and the abundant -OH / -COOH functional groups in starch demonstrates the interaction between starch and SiO₂. x There are strong chemical interactions between them. As a supplement to FTIR data, Figure 4 X-ray photoelectron spectroscopy (XPS) data (because samples from Examples 4-6 were excluded from the XPS characterization due to their electrochemical performance, as excessive doping would affect electrochemical performance; urea was selected with the optimal doping ratio found in melamine, but its performance was inferior to melamine, so samples from Examples 4-6 were excluded from the XPS characterization). The formation of O-Si-C bonds (at 103.2 eV in the Si 2p spectrum) confirmed the formation of SiO₂. x Strong chemical bonds are formed between it and starch. The C 1s spectrum reveals that starch is predominantly composed of C=O bonds (288.1 eV) due to the abundance of -COOH and -COO- groups. It also forms bonds with SiO₂. x After mixing, the CO / CN bond (286.6 eV) dominates, while, as reflected in the Si 2p spectrum, it also interacts with SiO. x O-Si-C bonds were formed. This proves that starch interacts with SiO₂. x The above results indicate a charge transfer between the -NH2 groups in melamine and the oxygen-containing functional groups in starch. Therefore, in the precursor slurry, starch, as the main binder, acts as a bridge between the nitrogen source and the active material particles, contributing to the uniform distribution of the solid matter and thus facilitating the dispersion of nitrogen heteroatoms in the calcined product.

[0081] like Figure 2 As shown, with the increase of melamine dosage, CN bonds (1560 cm⁻¹) are observed. -1 The enhancement of the absorption signal and the Si-O-Si bond (990cm) -1 The redshift of ). At the same time, according to Figure 3 The proportions of C, O, Si, and N in Examples 1-4 and Comparative Example 1 show that the proportion of N increases with increasing nitrogen doping concentration. This confirms that nitrogen heteroatoms have been successfully introduced into the integrated electrode.

[0082] like Figure 4 As shown, in the C 1s spectrum, a distinct CN bond appears at 285.7 eV as the melamine doping ratio increases, which corresponds to the increase in nitrogen doping.

[0083] In the N 1s spectrum, the nitrogen doping types in the carbonaceous structure are graphite-N, pyrrole-N and pyridine-N, with three CN bond types located at 401.0 eV, 400.1 eV and 398.7 eV, respectively. Among them, the five-membered ring N (pyrrole-N) accounts for the majority. The proportion of pyrrole-N is the highest in Example 2 and the proportion of pyridine-N is the highest in Example 3.

[0084] In the Si 2p spectra, Si-N bonds appeared at 100.9 eV for the samples of Examples 2 and 4, revealing the chemical interaction between the NC layer and the SiOx particles. Importantly, regardless of the amount of nitrogen source added, the Si 2p spectra consistently showed that Si-OC bonds (102.1 eV) were the dominant component. This indicates that in the integrated electrode, SiO... x The interaction with nitrogen heteroatoms is relatively weaker than that between the carbonaceous framework and SiO. x The interaction between them.

[0085] The micron-sized silicon-oxygen anode materials prepared in Examples 1-6 and Comparative Examples 1-2 were used to fabricate batteries. The specific steps are as follows: using the micron-sized silicon-oxygen anode materials prepared in Examples 1-6 and Comparative Examples 1-2 as the working electrode, a lithium sheet as the reference electrode, LB046 ether-based electrolyte, and a CR2032 battery module, the above components are assembled to obtain a half-cell. The electrochemical performance of the obtained lithium-ion half-cell is tested using a Blue Electric system, and the results are as follows. Figures 5-9 As shown.

[0086] Figure 5 The graph shows the cycle performance of batteries prepared from the final products obtained in Examples 1-6 and Comparative Example 1. Figure 6 The graph shows the rate performance of batteries prepared from the final products obtained in Examples 1-6 and Comparative Example 1. Figure 7 The graph shows the capacity retention performance of the batteries prepared from the final products obtained in Examples 1-5 and Comparative Example 1. Figure 8 The image shows the cycle performance of batteries prepared from the final products obtained in Example 2 and Comparative Examples 1-2. Figure 9 The rate performance diagrams are for batteries prepared from the final products obtained in Example 2 and Comparative Examples 1-2.

[0087] Depend on Figure 5 and Figure 6 It can be seen that the battery assembled from the micron-sized silicon-oxygen anode material prepared in Example 2 has higher specific capacity and cycle stability, and still exhibits significant performance improvement at a high rate of 3C. Figure 7 It can be seen that the battery assembled with the micron-sized silicon-oxygen anode material prepared in Example 2 has a higher capacity retention rate.

[0088] Figure 8 and Figure 9 The electrochemical performance of three electrodes (Comparative Example 1, Comparative Example 2 and Example 2) was compared.

[0089] The cycling performance graphs show that: Comparative Example 2, due to the lack of carbonization treatment and the absence of an integrated electrode, lacks a carbon framework to buffer the drastic volume changes during charge and discharge, resulting in the fastest capacity decay; Comparative Example 1's integrated carbon framework alleviates volume expansion, but due to the lack of doping, its conductivity is limited, and irreversible lithium loss still occurs; The nitrogen-doped carbon framework of Example 2 provides a uniform conductive network and active sites, promoting uniform lithium conversion, resulting in the highest capacity retention and the most gradual capacity decay.

[0090] The rate performance graphs show that: Comparative Example 2 experiences a sharp capacity drop at high rates; Comparative Example 1 shows some improvement in high-rate performance but is still insufficient; Example 2 exhibits the highest specific capacity at all rates, especially at 2C and 3C, which is attributed to nitrogen doping reducing interfacial impedance and accelerating lithium delithiation kinetics. In summary, the nitrogen-doped integrated electrode significantly outperforms Comparative Examples 1 and 2 in both cycle stability and rate performance. It is evident that industrialization cost is the main bottleneck limiting the application of such materials. The preparation method of this invention is expected to overcome this cost bottleneck, creating favorable conditions for the application of these materials.

[0091] The above embodiments are merely illustrative of several implementations of the present invention, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the invention patent. For those skilled in the art, any changes, modifications, substitutions, integrations, and parameter alterations to these embodiments without departing from the concept of the present invention are all within the protection scope of the present invention.

Claims

1. A method for preparing a nitrogen-doped integrated micron-sized silicon-oxygen anode material, characterized in that, Includes the following steps: The carbon source is dissolved in water and then mixed with silicon suboxide and a nitrogen source to obtain a mixed slurry; The mixed slurry is coated onto the current collector, and then the current collector is dried to obtain the electrode sheet; The electrode is carbonized to obtain the nitrogen-doped integrated micron silicon-oxygen anode material. The silicon suboxide has a particle size of 3-10 μm, the carbon source includes at least one of starch and lithium polyacrylate, and the nitrogen source includes at least one of melamine and urea.

2. The method for preparing the nitrogen-doped integrated micron-sized silicon-oxygen anode material according to claim 1, characterized in that, The mass ratio of silicon suboxide to the nitrogen source is 1:0.05~1.

3. The method for preparing the nitrogen-doped integrated micron-sized silicon-oxygen anode material according to claim 1, characterized in that, The mass ratio of silicon suboxide to the carbon source is 1~2:

1.

4. The method for preparing the nitrogen-doped integrated micron-sized silicon-oxygen anode material according to claim 1, characterized in that, The carbon source, silicon suboxide, and nitrogen source are mixed by stirring at a speed of 250-450 r / min for 3-6 h.

5. The method for preparing the nitrogen-doped integrated micron-sized silicon-oxygen anode material according to claim 1, characterized in that, The carbonization temperature is 300~700℃, and the time is 0.1~24h.

6. The method for preparing the nitrogen-doped integrated micron-sized silicon-oxygen anode material according to claim 1, characterized in that, The coating thickness of the mixed slurry on the current collector is 15~25μm.

7. The method for preparing the nitrogen-doped integrated micron-sized silicon-oxygen anode material according to claim 1, characterized in that, The drying of the current collector includes the following steps: first, drying in a forced-air drying oven at 60~80℃ for 0.1~1h, followed by drying in a vacuum drying oven at 80~120℃ for more than 12h.

8. The method for preparing the nitrogen-doped integrated micron-sized silicon-oxygen anode material according to claim 1, characterized in that, The current collector includes at least one of single-sided copper foil and porous copper foil.

9. A nitrogen-doped integrated micron-sized silicon-oxygen anode material, characterized in that, Prepared by the preparation method according to any one of claims 1 to 8.

10. A lithium-ion battery, characterized in that, Including the nitrogen-doped integrated micron silicon-oxygen anode material as described in claim 9.

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