A phosphorus oxide-coated silicon-containing material, a preparation method thereof and application thereof in a sulfide solid-state battery negative electrode material

Abstract

This invention belongs to the field of secondary battery technology, specifically relating to a phosphorus oxide-coated silicon-containing material, its preparation method, and its application in sulfide solid-state battery anode materials. The invention involves ball milling a mixture of elemental phosphorus and a silicon-containing material to obtain a phosphated material; the phosphated material is then oxidized in air to obtain the phosphorus oxide-coated silicon-containing material. The phosphorus oxide-coated silicon-containing material provided by this invention, as a highly stable silicon-based anode material, is suitable for sulfide all-solid-state batteries. It effectively isolates the conductive components from direct contact with the sulfide solid electrolyte, suppresses interfacial side reactions, and balances lithium-ion transport and structural stability. This is of great significance for improving the performance of silicon-based anodes in sulfide all-solid-state batteries.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery technology, specifically relating to a phosphorus oxide-coated silicon-containing material, its preparation method, and its application in sulfide solid-state battery anode materials. Background Technology

[0002] With the rapid development of new energy vehicles, portable electronic devices, and large-scale energy storage systems, the market demand for high-energy-density and high-safety rechargeable batteries is constantly increasing. Sulfide all-solid-state batteries use non-flammable solid electrolytes instead of traditional liquid electrolytes, offering advantages such as high safety and high energy density, and are considered an important development direction for next-generation high-performance energy storage devices.

[0003] In sulfide all-solid-state batteries, the anode material has a significant impact on the battery's energy density, cycle life, and rate performance. Silicon-based anode materials show promising application prospects due to their high theoretical specific capacity of approximately 3579 mAh / g, low lithium intercalation potential, and abundant resource reserves. Currently, silicon-carbon anodes, silicon-oxygen anodes, and pure silicon anodes have been extensively studied. However, the application of silicon anodes in sulfide all-solid-state batteries still faces significant challenges. On the one hand, silicon exhibits significant volume expansion during charge and discharge, which can easily lead to particle breakage, interfacial contact failure, and electrode structural instability. On the other hand, the carbon component in the electrode and the lithium-silicon alloy formed after lithium intercalation have strong electronic conductivity. When in direct contact with the sulfide solid electrolyte, it can easily induce the electrolyte to undergo reductive decomposition at low potentials, generating unstable interfacial products. This results in continuous consumption of active lithium and electrolyte, reduced coulombic efficiency in the first cycle, and increased interfacial impedance, severely affecting the battery's cycle stability and rate performance.

[0004] In existing technologies, methods such as surface coating, interface layer construction, or electrode structure optimization are commonly used to improve the interfacial stability between silicon-based anodes and sulfide solid electrolytes. However, existing interface modification strategies generally suffer from problems such as insufficient ion transport capacity, poor electronic insulation, unstable interfacial bonding, or difficulty in adapting to silicon volume changes, making it difficult to maintain effectiveness during long-term cycling. In particular, there is still a lack of effective means to suppress side reactions caused by direct contact between conductive carbon in the silicon-based anode and the sulfide electrolyte. Summary of the Invention

[0005] The purpose of this invention is to provide a phosphorus oxide-coated silicon-containing material, its preparation method, and its application in sulfide solid-state battery anode materials. The phosphorus oxide-coated silicon-containing material provided by this invention is suitable as a high-stability silicon-based anode material for sulfide all-solid-state batteries. It can effectively isolate the direct contact between conductive components and sulfide solid electrolyte, suppress interfacial side reactions, and take into account both lithium-ion transport and structural stability. It is of great significance for improving the application performance of silicon-based anodes in sulfide all-solid-state batteries.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a phosphorus oxide-coated silicon-containing material, comprising the following steps: Phosphorus and silicon-containing materials are mixed and ball-milled to obtain phosphated materials. The ball milling speed is 300~500 r / min and the time is 4~8 h. The phosphated material is oxidized in dry air to obtain the silicon-containing material coated with phosphorus oxide. The oxidation treatment temperature is 30~150℃, the time is 24~48h, and the relative humidity of the dry air is 15~40%.

[0007] Preferably, the phosphorus element includes one or more of white phosphorus, red phosphorus, black phosphorus, blue phosphorus, and purple phosphorus.

[0008] Preferably, the silicon-containing material includes silicon-carbon material and / or pure silicon material; the silicon-carbon material includes one or more of fumed silicon-carbon material (CVD silicon-carbon material), resin-based silicon-carbon material, biomass-based silicon-carbon material and graphite-based silicon-carbon material.

[0009] Preferably, the particle size of the silicon-carbon material is 1~20μm; the particle size of the pure silicon material is 20nm~20μm.

[0010] Preferably, the mass percentage of the phosphorus element in the silicon-containing material is 1-15%.

[0011] Preferably, the relative humidity of the dry air is 20-35%.

[0012] The present invention provides a phosphorus oxide-coated silicon-containing material prepared by the preparation method described above.

[0013] This invention provides the application of the phosphorus oxide-coated silicon-containing material described above in the anode material of sulfide solid-state batteries.

[0014] This invention provides a silicon-based anode for a sulfide solid-state battery, comprising the silicon-containing material coated with phosphorus oxide as described in the above technical solution.

[0015] This invention provides a sulfide solid-state battery, wherein the negative electrode is a silicon-based negative electrode of the sulfide solid-state battery described above.

[0016] This invention provides a method for preparing a silicon-containing material coated with phosphorus oxide, comprising the following steps: mixing elemental phosphorus with a silicon-containing material and ball milling to obtain a phosphated material, wherein the ball milling speed is 300-500 r / min and the time is 4-8 h; and oxidizing the phosphated material in dry air to obtain the silicon-containing material coated with phosphorus oxide, wherein the oxidation treatment temperature is 30-150℃ and the time is 24-48 h, and the relative humidity of the dry air is 15-40%. The preparation method provided by this invention uses high-energy ball milling to mix elemental phosphorus with a silicon-containing material, controlling the ball milling speed at 300-500 r / min and the time at 4-8 h. During the ball milling process, phosphorus undergoes sublimation vaporization-deposition, thereby coating the surface of the silicon-containing material to form a nano-coating layer. The obtained phosphated material was further subjected to a slow oxidation process in dry air (relative humidity of 15-40%). The oxidation temperature, time and relative humidity of the dry air were controlled to convert the phosphorus on the surface into phosphorus oxide in situ. The synthesized phosphorus oxide-coated silicon-containing material showed better cycle performance than the silicon-containing material and the phosphated material in electrochemical tests.

[0017] The phosphorus oxide-coated silicon-containing material provided by this invention is suitable as a high-stability silicon-based anode material for sulfide all-solid-state batteries. It can effectively isolate the direct contact between conductive components and sulfide solid electrolyte, suppress interfacial side reactions, and take into account both lithium-ion transport and structural stability. It is of great significance for improving the application performance of silicon-based anodes in sulfide all-solid-state batteries. Attached Figure Description

[0018] Figure 1 The image shows the microstructure and elemental distribution of the product prepared in Example 1. Figure 1 Image (a) in the image is a scanning electron microscope (SEM) image of the product prepared in Example 1. Figure 1 (b) in the diagram shows the EDS surface distribution of Si. Figure 1 (c) in the diagram is the EDS surface distribution plot of element P. Figure 1 (d) in the image is the elemental quantitative analysis spectrum obtained by energy dispersive spectroscopy (EDS). Figure 1 (e) in the diagram represents the EDS surface distribution of element C. Figure 1 (f) in the figure is the EDS surface distribution diagram of element O; Figure 2 The graphs show the performance and cycle performance of the assembled half-cell from Example 1. Figure 2 In Figure (a), the first charge-discharge (voltage-specific capacity) performance test curve of the half-cell assembled in Example 1 is shown. Figure 2 (b) in the figure represents the long-cycle performance curve at a 0.2C rate; Figure 3These are characterization graphs of the performance of the assembled half-cell and the first charge-discharge cycle of the full cell in Example 4. Figure 3 In Example 4, (a) shows the first constant current charge-discharge curves of the half-cells of μ-Si and POx@μ-Si materials at a rate of 0.1C. Figure 3 (b) in Example 3 shows the first charge-discharge curve of the full battery assembled based on two negative electrode materials; Figure 4 The image shows the microstructure and elemental distribution of the product prepared in Example 5. Figure 4 Image (a) is a scanning electron microscope (SEM) image of the product prepared in Example 5. Figure 4 (b) in the diagram shows the EDS surface distribution of Si. Figure 4 (c) in the figure is the EDS surface distribution diagram of element P; Figure 5 These are characterization graphs of the performance of the assembled half-cell and the first charge-discharge cycle of the full cell in Example 5. Figure 5 In Example 5, (a) shows the first constant current charge-discharge curves of the nano-Si and POx@nano-Si materials at a rate of 0.1C for the half-cell. Figure 5 (b) in Example 5 shows the first charge-discharge curve of the full battery assembled based on two negative electrode materials. Detailed Implementation

[0019] This invention provides a method for preparing a phosphorus oxide-coated silicon-containing material, comprising the following steps: Phosphorus and silicon-containing materials are mixed and ball-milled to obtain phosphated materials. The ball milling speed is 300~500 r / min and the time is 4~8 h. The phosphated material is oxidized in dry air to obtain the silicon-containing material coated with phosphorus oxide. The oxidation treatment temperature is 30~150℃, the time is 24~48h, and the relative humidity of the dry air is 15~40%.

[0020] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0021] This invention involves ball milling a mixture of elemental phosphorus and a silicon-containing material to obtain a phosphated material. The ball milling speed is 300-500 r / min, and the time is 4-8 h. In this invention, the elemental phosphorus preferably includes one or more of white phosphorus, red phosphorus, black phosphorus, blue phosphorus, and purple phosphorus; in the examples, red phosphorus or black phosphorus may be used. In this invention, the silicon-containing material preferably includes silicon-carbon materials and / or pure silicon materials. The silicon-carbon material preferably includes one or more of fumed silica (CVD) silicon-carbon materials, resin-based silicon-carbon materials, biomass-based silicon-carbon materials, and graphite-based silicon-carbon materials. The CVD silicon-carbon material is a silicon-carbon material prepared by chemical vapor deposition. The resin-based silicon-carbon material is a silicon-carbon material based on resin-based carbon. The biomass-based silicon-carbon material is a silicon-carbon material based on biomass carbon. The graphite-based silicon-carbon material is a silicon-carbon material based on graphite. In this invention, the silicon-carbon material comprises a carbon framework and porous silicon supported on the carbon framework. The pore size of the porous silicon is preferably 5-10 nm, more preferably 8 nm. The mass percentage of carbon in the silicon-carbon material is preferably 50-60%, more preferably 55-58%; the mass percentage of silicon is preferably 40-50%, more preferably 42-45%. This invention does not have special requirements regarding the source of the silicon-carbon material used; commercially available products or those prepared using conventional methods are acceptable.

[0022] In this invention, the particle size of the silicon-carbon material is preferably 1~20μm, more preferably 2~15μm, and even more preferably 5~10μm. The particle size of the pure silicon material is preferably 20nm~20μm, more preferably 50nm~10μm, and even more preferably 100nm~5μm.

[0023] In this invention, the mass percentage of the phosphorus element to the mass of the silicon-containing material is preferably 1-15%, more preferably 1.5-10%, further preferably 2-10%, and even more preferably 2.5-10%.

[0024] In this invention, the preferred conditions for the ball milling are: a ball-to-material ratio of 10-30:1, more preferably 15-25:1, and in this embodiment, 20:1. The preferred milling speed is 350-450 r / min, and in this embodiment, 400 r / min. The preferred milling time is 5-7 hours, and in this embodiment, 6 hours. The ball milling is performed in a protective gas atmosphere, which may be argon. The ball milling is performed under vacuum conditions. The ball milling is performed in a closed environment.

[0025] In this invention, the mixing ball milling is performed in a planetary ball mill. The mixing ball milling is carried out under vacuum conditions, and the localized high energy generated during the milling causes phosphorus to sublimate. After sublimation, the phosphorus condenses and deposits on the surface of the silicon-containing material particles, forming a nano-coating layer of elemental phosphorus.

[0026] In this invention, the phosphating material comprises a silicon-containing material and a nano-coating layer covering the surface of the silicon-containing material. The nano-coating layer is made of elemental phosphorus.

[0027] After obtaining the phosphating material, the present invention oxidizes the phosphating material in dry air to obtain the silicon-containing material coated with phosphorus oxide. The oxidation treatment temperature is 30~150℃, the time is 24~48h, and the relative humidity of the dry air is 15~40%. In the present invention, the air is dry air. The oxidation treatment temperature is preferably 35~100℃, more preferably 40~80℃, and even more preferably 40~50℃. The relative humidity of the dry air is preferably 20~40%, and in the embodiments it can be 20~35%. The oxidation treatment time is preferably 24~36h. The oxidation treatment can be carried out in a forced-air drying oven.

[0028] The present invention provides a phosphorus oxide-coated silicon-containing material prepared by the preparation method described above.

[0029] This invention provides the application of the phosphorus oxide-coated silicon-containing material described above in the anode material of sulfide solid-state batteries.

[0030] This invention provides a silicon-based anode for a sulfide solid-state battery, comprising the silicon-containing material coated with phosphorus oxide as described in the above technical solution.

[0031] This invention provides a sulfide solid-state battery, wherein the negative electrode is a silicon-based negative electrode of the sulfide solid-state battery described above.

[0032] In this invention, the electrolyte of the sulfide solid-state battery is a sulfide electrolyte. The negative electrode material is the phosphorus oxide-coated silicon-containing material described in the above technical solution. The counter electrode of the half-cell is a Li-In alloy, and the positive electrode of the full cell is an NCM811 positive electrode.

[0033] To further illustrate the present invention, the technical solutions provided by the present invention are described in detail below with reference to embodiments, but these should not be construed as limiting the scope of protection of the present invention. The resin-based silicon-carbon material used in the following embodiments includes a resin-carbon framework and porous silicon supported on the resin-carbon framework, wherein the pore size of the porous silicon is 8 nm. The mass percentage of resin-carbon is 55%; the mass percentage of porous silicon is 45%. The biomass-char-based silicon-carbon material used in the following embodiments includes a biomass-char framework and porous silicon supported on the biomass-char framework, wherein the pore size of the porous silicon is 8 nm. The mass percentage of biomass-char is 58%; the mass percentage of porous silicon is 42%.

[0034] Example 1 In this embodiment, red phosphorus was used as the phosphorus source, and resin-based silicon carbide material was used as the raw material. The particle size of the resin-based silicon carbide material was 5 μm. 50 mg of red phosphorus and 2 g of resin-based silicon carbide material were weighed out. In an argon-filled glove box, the red phosphorus and resin-based silicon carbide material were premixed in a mortar and pestle, and then fed in at a ball-to-material ratio of 20:1. After feeding, the ball milling jar was evacuated and sealed. The ball milling speed was controlled at 400 rpm, and the ball milling was carried out for 6 hours. After ball milling, the sample was taken out of the glove box and placed in a 50°C forced-air drying oven for oxidation treatment in dry air (relative humidity of 30%) at 50°C for 24 hours to ensure that the phosphorus coated on the surface of the resin-based silicon carbide material was oxidized, resulting in a phosphorus oxide-coated silicon-containing material (POx@Si / C).

[0035] Figure 1 The image shows the microstructure and elemental distribution of the product prepared in Example 1. Figure 1 Image (a) in the image is a scanning electron microscope (SEM) image of the product prepared in Example 1. Figure 1 (b) in the diagram shows the EDS surface distribution of Si. Figure 1 (c) in the diagram is the EDS surface distribution plot of element P. Figure 1 (d) in the image is the elemental quantitative analysis spectrum obtained by energy dispersive spectroscopy (EDS). Figure 1 (e) in the diagram represents the EDS surface distribution of element C. Figure 1 In the diagram, (f) represents the EDS surface distribution of element O. (From...) Figure 1 As shown in (a), the SEM image in secondary electron mode reveals the microstructure of individual material particles. With a scale bar of 1 μm, the particles are irregularly shaped blocks, approximately 2–3 μm in size, exhibiting intact morphology without significant breakage, indicating that the coating process did not severely damage the matrix particles. The minute surface undulations also provide a location reference for subsequent elemental distribution analysis using EDS surface scanning. Figure 1As shown in (d), the product prepared in Example 1 contained elements (c) (~0.27 keV), O (~0.52 keV), Si (~1.74 keV), and P (~2.01 keV), indicating the presence of characteristic elements from both the matrix (Si, C) and the coating layer (P, O). The Si peak showed the highest intensity, indicating that silicon is the main component of the matrix. The presence of the P and O peaks directly proves the successful introduction of the phosphorus oxide coating layer, rather than elemental signals from the matrix itself. Figure 1 As shown in (b), Si elements are highly concentrated inside the particles, uniformly distributed with clear boundaries, perfectly matching the morphology of the matrix particles. This indicates that silicon is the core matrix component of the material, with a continuous and complete distribution, without obvious agglomeration or deficiency. Figure 1 As shown in (c), the P element is distributed throughout the entire particle region, highly overlapping with the contour of the Si matrix, and exhibits a continuous distribution on the particle surface / overall. This proves that the phosphorus oxide coating layer is not locally attached, but uniformly covers the particle surface, achieving an overall coating effect. Figure 1 As shown in (e), the distribution of C elements basically coincides with the outline of the Si matrix, mainly concentrated inside the particles, and is uniformly distributed, providing a conductive network support for the silicon-based material. Figure 1 As shown in (f), the distribution of O and P elements is highly coordinated, both covering the entire particle area. This proves that the O element mainly originates from the phosphorus oxide coating layer (synchronous distribution of P and O), and may also contain oxygen signals from slight oxidation of the silicon surface. The co-distribution of P and O directly verifies the chemical composition of the phosphorus oxide coating layer. In summary, from Figure 1 It can be seen that in the phosphorus oxide-coated silicon-containing material prepared in Example 1, phosphorus is uniformly coated on its surface. Figure 1 (d) in the figure represents the elemental quantitative analysis spectrum of energy dispersive spectroscopy (EDS) (i.e., the analysis and calculation of the spectrum). Figure 1 By integrating the peak areas in the EDS spectrum of (d) in the image, we can obtain that the atomic percentage of phosphorus is approximately 1.5%. Figure 1 The results show that the Si / C particles in the matrix have complete morphology and are in the micrometer range; the target elements Si, C, P and O were all detected, and the phosphorus oxide coating layer was successfully introduced; the P and O elements are uniformly distributed on the particle surface and perfectly match the contour of the matrix, proving that the coating layer is uniform and continuous, and the designed coating effect has been achieved.

[0036] Figure 2The performance and cycle performance of the assembled half-cell with phosphorus oxide-coated silicon material prepared in Example 1 were investigated. The half-cell preparation method specifically included: using a general battery structure, testing in a PEEK mold battery at a test pressure of 60 MPa; adding a sulfide electrolyte to the mold battery; cold pressing into a sheet at 300 MPa; adding the negative electrode material (i.e., the phosphorus oxide-coated silicon material prepared in Example 1); and cold pressing at 300 MPa. The counter electrode used in the half-cell was a Li-In alloy, and the positive electrode used in the full cell was an NCM811 positive electrode. The half-cell test pressure was 60 MPa, and the full cell test pressure was 300 MPa. Figure 2 In Figure (a), the first charge-discharge (voltage-specific capacity) performance test curve of the half-cell assembled in Example 1 is shown. Figure 2 (b) in the figure is the long-cycle performance curve at a 0.2C rate. Figure 2 (a) shows the first charge-discharge curves at a rate of 0.1C. Compared with the uncoated Si / C material, the charge-discharge potential plateau of POx@Si / C shifts upward and the polarization decreases, indicating that the phosphorus oxide coating layer effectively improves the electrode reaction kinetics and reduces the interfacial impedance. Figure 2 (b) shows the long-cycle performance curves at 0.2C rate. The Si / C material exhibits severe capacity decay after 100 cycles, while the POx@Si / C material shows significantly improved cycle stability. It still maintains a high reversible specific capacity after 100 cycles (the capacity retention rate of the POx@Si / C half-cell is as high as 83% after 100 cycles), and the coulombic efficiency remains stable at a high level. This indicates that the phosphorus oxide coating layer effectively suppresses the structural pulverization and side reactions during the lithium insertion / extraction process of silicon-based materials, and significantly improves the cycle life of the electrode.

[0037] Example 2 In this embodiment, red phosphorus was used as the phosphorus source, and resin-based silicon carbide material was used as the raw material. The particle size of the resin-based silicon carbide material was 5 μm. 200 mg of red phosphorus and 2 g of resin-based silicon carbide material were weighed out. In an argon-filled glove box, the red phosphorus and resin-based silicon carbide material were premixed in a mortar and pestle, and then fed into the ball mill at a ball-to-material ratio of 20:1. After feeding, the ball mill jar was evacuated and sealed. The ball milling speed was controlled at 400 rpm, and the ball milling was carried out for 6 hours. After ball milling, the sample was taken out of the glove box and placed in a 50°C forced-air drying oven for oxidation treatment in dry air (relative humidity of 30%) at 50°C for 48 hours to ensure that the phosphorus coated on the surface of the resin-based silicon carbide material was oxidized, resulting in a phosphorus oxide-coated silicon-containing material.

[0038] Example 3 In this embodiment, red phosphorus was used as the phosphorus source, and resin-based silicon carbide material was used as the raw material. The particle size of the resin-based silicon carbide material was 5 μm. 50 mg of red phosphorus and 2 g of biomass-based silicon carbide material were weighed. In an argon-filled glove box, the red phosphorus and biomass-based silicon carbide material were premixed in a mortar and pestle, and then fed in at a ball-to-material ratio of 20:1. After feeding, the ball mill jar was evacuated and sealed. The ball milling speed was controlled at 400 rpm, and the ball milling was carried out for 6 hours. After ball milling, the sample was taken out of the glove box and placed in a 50°C forced-air drying oven for oxidation treatment in dry air (relative humidity of 30%) at 50°C for 48 hours to ensure that the phosphorus coating on the surface of the biomass-based silicon carbide material was oxidized, resulting in a phosphorus oxide-coated silicon-containing material.

[0039] Example 4 In this embodiment, red phosphorus was used as the phosphorus source, and micron-sized silicon with a particle size of approximately 5 μm was used as the raw material. 50 mg of red phosphorus and 2 g of silicon were weighed and premixed in an argon-filled glove box using a mortar and pestle. The mixture was then fed into the mill at a ball-to-material ratio of 20:1. After feeding, the milling jar was evacuated and sealed. The milling speed was controlled at 400 rpm, and milling was performed for a total of 6 hours. After milling, the sample was removed from the glove box and placed in a 50°C forced-air drying oven for oxidation treatment in dry air (30% relative humidity) at 50°C for 24 hours to ensure that the phosphorus coating on the silicon surface was oxidized, resulting in a phosphorus oxide-coated silicon-containing material (POx@μ-Si).

[0040] Figure 3 These are characterization graphs of the performance of the assembled half-cell and the first charge-discharge cycle of the full cell in Example 4. Figure 3 In Example 4, (a) shows the first constant current charge-discharge curves of the half-cells of μ-Si and POx@μ-Si materials at a rate of 0.1C. Figure 3 (b) in Example 3 shows the first charge-discharge curve of the full battery assembled based on two negative electrode materials. Figure 3 As shown in (a) of Example 4, both μ-Si and POx@μ-Si materials exhibit typical lithium insertion / extraction behavior of silicon-based anodes. The charge / discharge curve of POx@μ-Si material shows less polarization and a more stable potential plateau, indicating that the phosphorus oxide coating reduces the electrode interface impedance and improves the reaction kinetics without sacrificing the material's high specific capacity, with a reversible specific capacity exceeding 3000 mAh·g. -1 .Depend on Figure 3 As shown in (b), compared with μ-Si-based full cells, POx@μ-Si-based full cells exhibit lower charge-discharge polarization and higher reversible specific capacity, indicating that the phosphorus oxide coating layer can still effectively maintain the stability of the electrode interface in the full cell system, suppress electrolyte decomposition and silicon volume expansion effect, and show better potential for practical applications.

[0041] Example 5 In this embodiment, red phosphorus was used as the phosphorus source, and nano-silicon with a particle size of approximately 50 nm was used as the raw material. 50 mg of red phosphorus and 2 g of silicon were weighed and premixed in an argon-filled glove box using a mortar and pestle. The mixture was then fed into the mill at a ball-to-material ratio of 20:1. After feeding, the milling jar was evacuated and sealed. The milling speed was controlled at 400 rpm, and milling was performed for a total of 6 hours. After milling, the sample was removed from the glove box and placed in a 50°C forced-air drying oven for oxidation treatment in dry air (30% relative humidity) at 50°C for 24 hours to ensure that the phosphorus coating on the silicon surface was oxidized, resulting in a phosphorus oxide-coated silicon-containing material (POx@nano-Si).

[0042] Figure 4 The image shows the microstructure and elemental distribution of the product prepared in Example 5. Figure 4 Image (a) is a scanning electron microscope (SEM) image of the product prepared in Example 5. Figure 4 (b) in the diagram shows the EDS surface distribution of Si. Figure 4 In diagram (c), the EDS surface distribution plot of element P is shown. Figure 4 As can be seen from (a) in Example 5, the product prepared in Example 5 shows that the particles are irregularly shaped blocks with a size of about 1~2 μm, with complete morphology and no obvious breakage or agglomeration. Figure 4 (b) shows that the Si element is concentrated in the particle region, which is highly consistent with the matrix morphology, indicating that silicon is the core matrix component of the material. Figure 4 (c) shows that the P element is uniformly distributed in the particle region and completely coincides with the outline of the Si matrix, proving that the phosphorus oxide coating layer is successfully and uniformly coated on the surface of the micron-sized silicon particles, achieving the target coating effect.

[0043] Figure 5 These are characterization graphs of the performance of the assembled half-cell and the first charge-discharge cycle of the full cell in Example 5. Figure 5 In Example 5, (a) shows the first constant current charge-discharge curves of the nano-Si and POx@nano-Si materials at a rate of 0.1C for the half-cell. Figure 5 (b) in Example 5 shows the first charge-discharge curve of the full battery assembled based on two negative electrode materials. Figure 5 As shown in (a), both materials exhibit typical lithium insertion / extraction behavior of silicon-based anodes. The charge / discharge curve of the POx@nano-Si material shows less polarization, indicating that the phosphorus oxide coating reduces the electrode interface impedance and improves the reaction kinetics without sacrificing the high specific capacity of the nano-silicon material. Figure 5As shown in (b), compared with nano-Si-based full cells, POx@nano-Si-based full cells exhibit lower charge-discharge polarization and higher reversible specific capacity, indicating that the phosphorus oxide coating layer can effectively maintain electrode interface stability and suppress electrolyte decomposition and silicon volume expansion effects in the full cell system, demonstrating superior potential for practical applications. In summary, Figure 5 This indicates that the capacity of the half-cell and full-cell assembled from the phosphorus oxide-coated silicon-containing material prepared in Example 5 is also improved accordingly.

[0044] Comparative Example 1 50 mg of red phosphorus was heated to 450 °C under an inert atmosphere (argon) to sublimate and vaporize, and then held at that temperature for 6 hours, thereby depositing the red phosphorus onto the surface of 2 g of resin-based silicon-carbon material. However, in the method provided in Comparative Example 1, the red phosphorus could not be effectively deposited onto the silicon-carbon surface and could not replace the strong CP bond imparted by high-energy ball milling.

[0045] Comparative Example 2 50 mg of red phosphorus and 1.5 mg of elemental sulfur were heated to 450 °C under an inert atmosphere (argon) to sublimate and vaporize the red phosphorus and elemental sulfur, and held at this temperature for 6 h. Then the temperature was lowered to 280 °C and held for 10 h, so that the red phosphorus and sulfur were deposited on the surface of 2 g of resin-based silicon carbon. Although PSC can uniformly coat P, the phosphorus that has not undergone surface oxidation will still form Li3P, which is a conductor, during the cycling process of the solid-state battery, and cannot effectively prevent the generation of side reactions.

[0046] Comparative Example 3 The resin-based silicon-carbon from Example 1 was used as the negative electrode material to assemble half-cells and full-cells, and the assembly methods for the half-cells and full-cells were the same as those in Example 1.

[0047] Comparative Example 4 Half-cells and full-cells were assembled using 5μm silicon as the negative electrode material in Example 4, and the assembly methods for the half-cells and full-cells were the same as in Example 1.

[0048] Comparative Example 5 Half-cells and full-cells were assembled using 50 nm nano-silicon as the negative electrode material in Example 5, and the assembly methods for the half-cells and full-cells were the same as in Example 1.

[0049] Comparative Example 6 This comparative example uses red phosphorus as the phosphorus source and resin-based silicon carbide material as the raw material. The particle size of the resin-based silicon carbide material is 5 μm. 100 mg of red phosphorus and 2 g of resin-based silicon carbide material were weighed out. In an argon-filled glove box, the red phosphorus and resin-based silicon carbide material were premixed in a mortar and pestle, and then fed into the ball mill at a ball-to-material ratio of 20:1. After feeding, the ball mill jar was evacuated and sealed. The ball milling speed was controlled at 400 rpm, and the milling was carried out for 6 hours. After milling, the sample was removed from the glove box.

[0050] Comparative Example 6 uses a similar inert atmosphere ball milling method to surface-coat red phosphorus and resin-based silicon-carbon anode materials, so that phosphorus is covalently bonded or physically adsorbed on the surface of resin-based silicon-carbon particles. However, phosphorus that has not undergone surface oxidation will still form Li3P, which is a conductive electron, during the cycling process of the sulfide solid-state battery, and cannot effectively prevent the generation of side reactions.

[0051] Table 1. Electrical properties of the negative electrode materials prepared in the examples and comparative examples.

[0052] As can be seen from the above embodiments, the method provided by the present invention involves mixing phosphorus (including black phosphorus and red phosphorus) with silicon-carbon / pure silicon through high-energy ball milling. During the ball milling process, phosphorus undergoes a vaporization-deposition process, thereby coating the surface of silicon-carbon or silicon to form a nano-coating layer. The phosphated silicon-carbon material or silicon is then subjected to a slow oxidation process in dry air at a temperature of 50°C, thereby converting the surface-coated phosphorus into phosphorus oxides in situ. The synthesized phosphorus oxide-coated silicon-carbon material exhibits better cycle performance in electrochemical tests than pure silicon-carbon material and phosphorus-coated silicon-carbon material.

[0053] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for producing a phosphorus oxide-coated silicon-containing material, characterized by, Includes the following steps: Phosphorus and silicon-containing materials are mixed and ball-milled to obtain phosphated materials. The ball milling speed is 300~500 r / min and the time is 4~8 h. The phosphated material is oxidized in dry air to obtain the silicon-containing material coated with phosphorus oxide. The oxidation treatment temperature is 30~150℃, the time is 24~48h, and the relative humidity of the dry air is 15~40%.

2. The production method according to claim 1, characterized by, The phosphorus element includes one or more of white phosphorus, red phosphorus, black phosphorus, blue phosphorus, and purple phosphorus.

3. The preparation method according to claim 1, characterized in that, The silicon-containing material includes silicon-carbon material and / or pure silicon material; the silicon-carbon material includes one or more of the following: fumed silicon-carbon material, resin-based silicon-carbon material, biomass-based silicon-carbon material, and graphite-based silicon-carbon material.

4. The preparation method according to claim 3, characterized in that, The particle size of the silicon-carbon material is 1~20μm; the particle size of the pure silicon material is 20nm~20μm.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The mass percentage of phosphorus in the silicon-containing material is 1-15%.

6. The preparation method according to claim 1, characterized in that, The relative humidity of the dry air is 20-35%.

7. The phosphorus oxide-coated silicon-containing material prepared by the preparation method according to any one of claims 1 to 6.

8. The application of the phosphorus oxide-coated silicon-containing material according to claim 7 in the anode material of sulfide solid-state batteries.

9. A silicon-based negative electrode for a sulfide solid-state battery, characterized in that, This includes the phosphorus oxide-coated silicon-containing material as described in claim 7.

10. A sulfide solid-state battery, characterized in that, Its negative electrode is the silicon-based negative electrode of the sulfide solid-state battery according to claim 9.

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