A phosphorus-doped P-Si@RGO heterostructure composite material, a preparation method and application thereof

Abstract

The application relates to the field of new energy material preparation, in particular to a phosphorus-doped P-Si@RGO heterostructure composite material and a preparation method and application thereof. The steps are as follows: after aluminum-silicon alloy is etched by hydrochloric acid, P-Si material is obtained; then a phosphorus source and an organic compound are dissolved in ammonia water and mixed with the P-Si to obtain A liquid; the A liquid is subjected to surface modification by APTES to obtain B liquid; the B liquid and a liquid graphene oxide dispersion liquid are mixed and a surfactant is added, and after uniform mixing, D liquid is obtained; the D liquid is subjected to hydrothermal reaction, and after filtration, black precipitate is obtained; after the black precipitate is washed, dried and subjected to heat preservation annealing, the phosphorus-doped P-Si@GO heterostructure composite material is obtained. The material has the characteristics of simple preparation process, good electrical contact performance, good cycle performance and capacity which is not easy to decay.

Description

Technical Field

[0001] This invention relates to the field of new energy material preparation, specifically to a phosphorus-doped P-Si@RGO heterostructure composite material, its preparation method, and its application. Background Technology

[0002] With the development of human civilization, primary fossil fuels such as petroleum no longer meet contemporary people's demands for sustainable, clean, environmentally friendly, and sustainable energy. The development of renewable energy and related energy storage technologies is increasingly attracting the attention of researchers and industry professionals. Secondary batteries, as an energy storage technology that converts chemical energy into electrical energy, have become a key research focus in the new energy field. Compared to traditional secondary batteries, lithium-ion batteries have advantages such as high energy density, low self-discharge, higher output voltage, and longer lifespan, which has garnered widespread attention from researchers and industry professionals. The rapid development of new energy electric vehicles, mobile communication devices, portable electronic products, and energy storage equipment, coupled with national subsidies for new energy vehicles, has driven the development of lithium-ion batteries.

[0003] However, the theoretical capacity of commercial graphite anodes is poor (370 mAh g). -1 In practice, existing carbon-based anode materials can no longer meet various application needs. Therefore, high-performance non-carbon-based alternative anode materials are receiving increasing attention. Among these anode materials, silicon-based anode materials are considered the most promising alternative anode materials due to their low cost, environmental friendliness, abundant reserves, low operating potential, and high theoretical capacity (4200 mAh g). -1 However, due to the large volume change of Si materials during Li+ insertion / extraction, the electrical contact is weak, the capacity retention is poor, and the cycling stability is poor, which greatly restricts its practical application. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a phosphorus-doped P-Si@RGO heterostructure composite material, its preparation method and application. The preparation process of this material is simple, the material has good electrical contact performance, good cycle performance and its capacity is not easily decayed.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a phosphorus-doped P-Si@RGO heterostructure composite material includes the following steps:

[0007] S1. After etching the aluminum-silicon alloy with hydrochloric acid, P-Si material is obtained. Then, phosphorus source and organic compound are dissolved in ammonia water and mixed with P-Si to obtain solution A. Solution A is then surface-modified with APTES to obtain solution B.

[0008] S2. Mix solution B and liquid graphene oxide dispersion and add surfactant. After mixing evenly, solution D is obtained.

[0009] S3. The D liquid is subjected to a hydrothermal reaction, filtered to obtain a black precipitate, and the black precipitate is washed, dried and annealed to obtain the phosphorus-doped P-Si@GO heterostructure composite material.

[0010] The phosphorus source described in S1 includes sodium dihydrogen phosphate, sodium phosphate, phytic acid, or phosphoric acid.

[0011] The organic compounds described in S1 include resorcinol, phenol, and hydroquinone.

[0012] The pH value of solution A described in S1 is adjusted by a surfactant, and the pH value of solution A is -1 to 0.

[0013] The surfactants described in S2 include CTAB, PVB, and APS.

[0014] The hydrothermal reaction described in S3 is carried out at room temperature for 2 hours, and requires a settling time of 10 hours.

[0015] The drying temperature described in S3 is 50-100℃, and the drying time is 8-24h.

[0016] The temperature for heat preservation described in S3 is 600℃-800℃, the heat preservation time is 2h-4h, and the heat preservation atmosphere is Ar gas.

[0017] A phosphorus-doped P-Si@RGO heterostructure composite material, wherein the molar ratio of P, Si and GO is a:b:c, where a is 0.5-1.0, b is 1.5-2.0, and c is 2.0.

[0018] An application of a phosphorus-doped P-Si@GO heterostructure composite material, wherein the phosphorus-doped P-Si@GO heterostructure composite material is used as a negative electrode material for lithium-ion batteries.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] The preparation process of this invention is as follows: An aluminum-silicon alloy is etched with hydrochloric acid to obtain a P-Si material. Then, a phosphorus source and ammonia are dissolved in an organic compound and mixed with the P-Si to obtain solution A. The nano-sized phosphorus-doped P-Si particles can prevent the agglomeration of specific nanostructure particles during crystal growth, thus buffering the volume effect of the material. Furthermore, the phosphorus-doped P-Si heterostructure can induce an internal electric field, further generating charge-driven force, solving the problem of low material conductivity. Solution A is surface-modified with APTES to obtain solution B. Solution B is mixed with a liquid graphene oxide dispersion and a surfactant is added. After uniform mixing, solution D is obtained. Combining solution B with graphene oxide (GO), which has excellent conductivity, can give the material a large specific surface area and excellent mechanical flexibility. This not only effectively promotes electron and ion transport but also effectively helps alleviate volume expansion during lithium-ion insertion / extraction, maintaining structural stability. Solution D undergoes a hydrothermal reaction, and after filtration, a black precipitate is obtained. The black precipitate is washed, dried, and annealed at a heat treatment temperature to obtain the phosphorus-doped P-Si@GO heterostructure composite material. Compared with traditional methods, the present invention has a simpler process, is easier to operate, and can avoid secondary pollution of the environment by materials.

[0021] The phosphorus-doped P-Si@RGO heterostructure composite material of this invention has a molar ratio of P, Si, and GO of a:b:c, where a is 0.5-1.0, b is 1.5-2.0, and c is 2.0. Phosphorus doping in the material provides multiple charge-discharge reactions at different potentials, generating abundant interfaces, accelerating electron transfer, increasing potential ion storage sites, and buffering the volume effect of the material. The porous structure can buffer Si expansion during charge-discharge processes. Silicon materials with high specific surface area and typical porous structures facilitate rapid diffusion of lithium ions into the electrode, improving the lithium ion transfer rate. The large-pore structure retained during cycling acts as an expansion buffer space, reducing electrode pulverization and electrode structure damage, and can significantly improve cycle life and reversibility. Furthermore, the combination of phosphorus-doped P-Si and graphene oxide (GO), which has excellent conductivity, gives the material a large specific surface area and excellent mechanical flexibility. This not only effectively promotes electron and ion transport but also effectively helps alleviate volume expansion during lithium ion insertion / extraction, maintaining structural stability and thus enabling the reaction process to proceed more quickly and smoothly.

[0022] The phosphorus-doped P-Si@RGO heterostructure composite material of the present invention, as a negative electrode material for lithium-ion batteries, overcomes the problems of large volume change of Si materials during Li+ insertion / extraction, which leads to weak electrical contact, poor capacity retention and poor cycle stability, and improves the application performance of Si materials in lithium-ion batteries. Attached Figure Description

[0023] Figure 1This is the XRD pattern of the phosphorus-doped P-Si@GO heterostructure composite material after heat treatment and annealing at 600℃ in an embodiment of the present invention.

[0024] Figure 2 This is a SEM image of the phosphorus-doped P-Si@GO heterostructure composite material after heat treatment and annealing at 600℃ in an embodiment of the present invention.

[0025] Figure 3 This is a cycling performance diagram of the phosphorus-doped P-Si@GO heterostructure composite material after heat treatment and annealing at 600℃ in an embodiment of the present invention.

[0026] Figure 4 This is the XRD pattern of the phosphorus-doped P-Si@GO heterostructure composite material after heat treatment and annealing at 700℃ in an embodiment of the present invention.

[0027] Figure 5 This is a SEM image of the phosphorus-doped P-Si@GO heterostructure composite material after heat treatment and annealing at 700℃ in an embodiment of the present invention.

[0028] Figure 6 This is a cycling performance diagram of the phosphorus-doped P-Si@GO heterostructure composite material after heat treatment and annealing at 700℃ in an embodiment of the present invention.

[0029] Figure 7 This is the XRD pattern of the phosphorus-doped P-Si@GO heterostructure composite material after heat treatment and annealing at 800℃ in an embodiment of the present invention.

[0030] Figure 8 This is a SEM image of the phosphorus-doped P-Si@GO heterostructure composite material after heat treatment and annealing at 800℃ in an embodiment of the present invention.

[0031] Figure 9 This is a cycling performance diagram of the phosphorus-doped P-Si@GO heterostructure composite material after heat treatment and annealing at 800℃ in an embodiment of the present invention. Detailed Implementation

[0032] The invention will now be further described with reference to the accompanying drawings.

[0033] A method for preparing a phosphorus-doped P-Si@RGO heterostructure composite material includes the following steps:

[0034] S1. After etching the aluminum-silicon alloy with hydrochloric acid, P-Si material is obtained. Then, phosphorus source and organic compound are dissolved in ammonia water and mixed with P-Si to obtain solution A. Solution A is then surface-modified with APTES to obtain solution B.

[0035] The phosphorus source includes sodium dihydrogen phosphate, sodium phosphate, phytic acid, or phosphoric acid.

[0036] The organic compounds mentioned include resorcinol, phenol, and hydroquinone.

[0037] The pH value of solution A is adjusted by a surfactant, and the pH value of solution A is -1 to 0.

[0038] S2. Mix solution B and liquid graphene oxide dispersion and add surfactant. After mixing evenly, solution D is obtained.

[0039] The surfactants mentioned include CTAB, PVB, and APS.

[0040] S3. The D liquid is subjected to a hydrothermal reaction, filtered to obtain a black precipitate, and the black precipitate is washed, dried and annealed to obtain the phosphorus-doped P-Si@GO heterostructure composite material.

[0041] The hydrothermal reaction is carried out at room temperature for 2 hours, and requires a settling time of 10 hours.

[0042] The drying temperature is 50-100℃, and the drying time is 8-24 hours.

[0043] The temperature during the heat preservation is 600℃-800℃, the heat preservation time is 2h-4h, and the heat preservation atmosphere is Ar gas.

[0044] The specific preparation process of this invention is as follows:

[0045] Step 1: React 4-7g of aluminum-silicon alloy with HCl to remove Al and obtain P-Si. Then dissolve the phosphorus source and organic compound in ammonia water and stir thoroughly for a period of time until the phosphorus source is completely dissolved in the ammonia water. Use the resulting mixture as solution A. Mix solution A with APTES solution and stir for a period of time to obtain the modified mixture solution B. Take 50-150ml of graphene solution and ultrasonically disperse it for a period of time to obtain a graphene dispersion, which is used as solution C. The phosphorus source includes sodium dihydrogen phosphate, sodium phosphate, phytic acid, or phosphoric acid. The organic compound includes resorcinol, phenol, or hydroquinone.

[0046] Step 2: Mix solution B and solution C, then add a surfactant and mix thoroughly to obtain solution D. The surfactant used may be CTAB, PVB, or APS.

[0047] Step 3: Stir the D solution for a period of time to allow the phosphorus and C sources to fully react with P-Si and mix thoroughly. Then, perform ultrasonic dispersion for a period of time to further promote mixing. Next, add the entire mixed volume to a solvothermal reactor and react at room temperature for a period of time to allow the materials to fully react. After filtration, a black precipitate is obtained. The resulting grayish-black precipitate is thoroughly washed and then dried in a vacuum drying oven at 50-100℃ for 8-24 hours to obtain the phosphorus-doped P-Si@GO heterostructure composite material. The molar ratio of P, Si, and GO is a:b:c, where a is 0.5-1.0, b is 1.5-2.0, and c is 2.0.

[0048] Example 1:

[0049] Step 1: Prepare 300 mL of 2 mol / L HCl solution. Slowly add 5 g of aluminum-silicon alloy to the prepared HCl solution and stir magnetically for 24 h at room temperature to completely remove Al. Collect the reaction product by filtration, and then place the reaction product in an oven and vacuum dry at 60 °C for 24 h to obtain P-Si. Then, dissolve 0.075 g of resorcinol and 0.05 g of sodium dihydrogen phosphate in 75 μL of ammonia solution and stir thoroughly with P-Si for a period of time to obtain mixture A. Stir mixture A with APTES for 1 h to obtain modified mixture B. Take 100 mL of graphene solution and ultrasonically disperse for 1 h to obtain graphene dispersion, which is used as solution C.

[0050] Step 2: Mix solution B and solution C and add surfactant CTAB. Stir for another 1 hour to mix solution B, solution C and surfactant evenly to obtain solution D.

[0051] Step 3: Stir the D liquid for 2 hours, then ultrasonically disperse it for 1 hour. After that, add the entire mixed volume to a solvothermal reactor and react at room temperature for 2 hours. Then let it stand for 10 hours, filter to obtain a black precipitate. After thoroughly washing the black precipitate, put it into a vacuum drying oven and dry it at 60°C for 12 hours. Then anneal the obtained material in an Ar atmosphere tube furnace at 600°C for 2 hours to obtain the phosphorus-doped P-Si@GO heterostructure composite material.

[0052] The prepared active material, conductive carbon black, and binder were weighed according to a mass ratio of 7:2:1. First, the active material, conductive carbon black, and binder were ground and mixed evenly in a mortar. Then, NMP solution was added dropwise to prepare a slurry. The resulting slurry was uniformly coated onto copper foil, and the coated battery electrode was placed in a vacuum drying oven and dried at 60°C for 12 hours. The dried electrode was cut into 12mm small round electrode sheets as negative electrodes. For the preparation of the lithium-ion battery, a lithium metal sheet was used as the counter electrode, Celgard 2400 polypropylene as the separator, and a 1:1 volume ratio of ethylene carbonate and diethyl carbonate was used as the electrolyte. The electrolyte was lithium hexafluorophosphate. A CR2032 type button cell was assembled in an argon-filled glove box.

[0053] Analysis of the phosphorus-doped P-Si@GO heterostructure composite material prepared in Example 1 revealed that, through XRD analysis and by... Figure 1 The XRD spectra of AlSi, phosphorus-doped P-Si, and phosphorus-doped P-Si@GO show five distinct peaks at 28.4°, 47.3°, 56.1°, 69.1°, and 76.4°, originating from the (1 1 1), (2 2 0), (3 1 1), (4 0 0), and (3 3 1) lattice planes of Si, respectively. This matches the standard spectrum of silicon (JCPDS No. 27-1402) very well. The XRD spectra of phosphorus-doped P-Si and phosphorus-doped P-Si@GO show no significant difference, indicating that the carbon shell of the coating is amorphous. Figure 2 SEM analysis reveals that the phosphorus-doped P-Si@GO heterostructure composite material exhibits an overall microspherical structure, with the microspheres stacked and overlapping. These microspheres are generally small in diameter, ranging from approximately 1 μm to 10 μm. Figure 3 The figure shows the cycling performance of the phosphorus-doped P-Si@GO heterostructure composite material after annealing at 600℃.

[0054] Example 2:

[0055] Step 1: Prepare 240 mL of 2 mol / L HCl solution. Slowly add 4 g of aluminum-silicon alloy to the prepared HCl solution and stir magnetically at room temperature for 24 h to completely remove Al. Collect the reaction product by filtration, and then place the reaction product in an oven and vacuum dry at 60 °C for 24 h to obtain P-Si. Then, dissolve 0.085 g of resorcinol and 0.06 g of sodium dihydrogen phosphate in 75 μL of ammonia solution and stir thoroughly with P-Si for a period of time to obtain mixture A. Stir mixture A with APTES for 1 h to obtain modified mixture B. Take 150 mL of graphene solution and ultrasonically disperse for 1.5 h to obtain graphene dispersion, which is used as solution C.

[0056] Step 2: Mix solution B and solution C and add surfactant CTAB. Stir for another 2 hours to mix solution B, solution C and surfactant evenly to obtain solution D.

[0057] Step 3: Stir the D liquid for 2 hours, then ultrasonically disperse it for 1 hour. After that, add the entire mixed volume to a solvothermal reactor and react at room temperature for 2 hours. Then let it stand for 10 hours, filter to obtain a black precipitate. After thoroughly washing the black precipitate, put it into a vacuum drying oven and dry it at 60°C for 12 hours. Then anneal the obtained material in an Ar atmosphere tube furnace at 700°C for 2 hours to obtain the phosphorus-doped P-Si@GO heterostructure composite material.

[0058] The prepared active material, conductive carbon black, and binder were weighed according to a mass ratio of 7:2:1. First, the active material, conductive carbon black, and binder were ground and mixed evenly in a mortar, and then NMP solution was added dropwise to form a slurry. The resulting slurry was uniformly coated onto copper foil, and the coated battery electrode was placed in a vacuum drying oven and dried at 60°C for 12 hours. The dried electrode was cut into 12mm small round electrode sheets as negative electrodes. For the preparation of the lithium-ion battery, a CR2032 type button cell was assembled in an argon-filled glove box using a lithium metal sheet as the counter electrode, Celgard 2400 polypropylene as the separator, and a 1:1 volume ratio of ethylene carbonate and diethyl carbonate as the electrolyte.

[0059] According to Example 2, the phosphorus-doped P-Si@GO heterostructure composite material after annealing at 700℃ was prepared by... Figure 4 The XRD spectra of AlSi, phosphorus-doped P-Si, and phosphorus-doped P-Si@GO show five distinct peaks at 28.4°, 47.3°, 56.1°, 69.1°, and 76.4°, originating from the (1 1 1), (2 2 0), (3 1 1), (4 0 0), and (3 3 1) lattice planes of Si, respectively. This matches the standard spectrum of silicon (JCPDS No. 27-1402) very well. The XRD spectra of phosphorus-doped P-Si and phosphorus-doped P-Si@GO show no significant difference, indicating that the carbon shell of the coating is amorphous and... Figure 5 As can be seen from the SEM image, the phosphorus-doped P-Si@GO heterostructure composite material has a microspherical porous structure with uniform distribution and varying material size, with the diameter ranging from 500 nm to 5 μm. Through comparison, it was found that when the holding temperature is increased to 700℃, the overall size of the composite material will decrease, which can further prevent the volume effect and ensure the cycling stability of the material. Figure 6 The graph shows the cycling performance of the phosphorus-doped P-Si@GO heterostructure composite material after annealing at 700℃.

[0060] Example 3:

[0061] Step 1: Prepare 180 mL of 2 mol / L HCl solution. Slowly add 3 g of aluminum-silicon alloy to the prepared HCl solution and stir magnetically for 24 h at room temperature to completely remove Al. Collect the reaction product by filtration, and then place the reaction product in an oven and vacuum dry at 60 °C for 24 h to obtain P-Si. Then, dissolve 0.095 g of resorcinol and 0.07 g of sodium dihydrogen phosphate in 75 μL of ammonia solution and stir thoroughly with P-Si for a period of time to obtain mixture A. Stir mixture A with APTES for 1 h to obtain modified mixture B. Take 200 mL of graphene solution and ultrasonically disperse for 2 h to obtain graphene dispersion, which is used as solution C.

[0062] Step 2: Mix solution B and solution C and add surfactant CTAB. Stir for another 1 hour to mix solution B, solution C and surfactant evenly to obtain solution D.

[0063] Step 3: Stir the D liquid for 2 hours, then ultrasonically disperse it for 1 hour. After that, add the entire mixed volume to a solvothermal reactor and react at room temperature for 2 hours. Then let it stand for 10 hours, filter to obtain a black precipitate. After thoroughly washing the black precipitate, put it into a vacuum drying oven and dry it at 60°C for 12 hours. Then anneal the obtained material in an Ar atmosphere tube furnace at 800°C for 2 hours to obtain the phosphorus-doped P-Si@GO heterostructure composite material.

[0064] The prepared active material, conductive carbon black, and binder were weighed according to a mass ratio of 7:2:1. First, the active material, conductive carbon black, and binder were ground and mixed evenly in a mortar, and then NMP solution was added dropwise to form a slurry. The resulting slurry was uniformly coated onto copper foil, and the coated battery electrode was placed in a vacuum drying oven and dried at 60°C for 12 hours. The dried electrode was cut into 12mm small round electrode sheets as negative electrodes. For the preparation of the lithium-ion battery, a CR2032 type button cell was assembled in an argon-filled glove box using a lithium metal sheet as the counter electrode, Celgard 2400 polypropylene as the separator, and a 1:1 volume ratio of ethylene carbonate and diethyl carbonate as the electrolyte.

[0065] The phosphorus-doped P-Si@GO heterostructure composite material prepared in Example 3 after annealing at 800℃ is composed of... Figure 7The XRD spectra of AlSi, phosphorus-doped P-Si, and phosphorus-doped P-Si@GO show five distinct peaks at 28.4°, 47.3°, 56.1°, 69.1°, and 76.4°, originating from the (1 1 1), (2 2 0), (3 1 1), (4 0 0), and (3 3 1) lattice planes of Si, respectively. This matches the standard spectrum of silicon (JCPDS No. 27-1402) very well. The XRD spectra of phosphorus-doped P-Si and phosphorus-doped P-Si@GO show no significant difference, indicating that the carbon shell of the coating is amorphous and... Figure 8 As can be seen from the SEM image, the phosphorus-doped P-Si@GO heterostructure composite material exhibits an overall microspherical porous structure with uniform distribution. Figure 9 The graph shows the cycling performance of the phosphorus-doped P-Si@GO heterostructure composite material after annealing at 800℃.

[0066] Preferably, this invention utilizes a solvothermal method to prepare phosphorus-doped P-Si@GO heterostructure composite materials: first, in a sealed container, a high-temperature and high-pressure reaction environment is created by heating the reaction system in solution, thereby causing the material to crystallize and grow into a specific nanostructure. Generally, the resulting product has high purity, good crystallinity, and high yield. By adjusting various reaction parameters, the morphology and crystal growth characteristics of the product can be controlled, resulting in nanostructures with special morphologies and crystal structures. The nano-sized phosphorus-doped P-Si particles can further prevent particle aggregation and buffer the volume effect of the material. This invention obtains P-Si material by etching an aluminum-silicon alloy with hydrochloric acid, then dissolves a phosphorus source and ammonia in an organic compound and mixes it with P-Si to obtain solution A. The nano-sized phosphorus-doped P-Si particles can prevent the aggregation of specific nanostructure particles during crystal growth, buffering the volume effect of the material. Furthermore, the phosphorus-doped P-Si heterostructure can induce an internal electric field, further generating charge-driven force, solving the problem of low material conductivity. Liquid A was surface-modified with APTES to obtain liquid B. Liquid B was then mixed with a liquid graphene oxide dispersion and a surfactant was added. After thorough mixing, liquid D was obtained. Composite with graphene oxide (GO), which possesses excellent conductivity, the material exhibits a large specific surface area and superior mechanical flexibility. This not only effectively promotes electron and ion transport but also helps alleviate volume expansion during lithium-ion insertion / extraction, maintaining structural stability. Liquid D was subjected to hydrothermal reaction, filtration, washing, drying, and annealing to obtain the phosphorus-doped P-Si@GO heterostructure composite material. The synthesis of this material via a solvothermal method is simple, convenient, and yields a high rate. The phosphorus-doped P-Si@GO heterostructure composite material exhibits high specific energy and excellent electrochemical performance, while avoiding secondary environmental pollution.

[0067] A phosphorus-doped P-Si@RGO heterostructure composite material, wherein the molar ratio of P, Si and GO is a:b:c, where a is 0.5-1.0, b is 1.5-2.0, and c is 2.0.

[0068] Preferably, the phosphorus-doped P-Si@RGO heterostructure composite material of the present invention provides multiple charge-discharge reactions at different potentials due to phosphorus doping, generating abundant interfaces, accelerating electron transfer, increasing potential ion storage sites, and buffering the volume effect of the material. The porous structure can buffer Si expansion during charge-discharge. Silicon materials with high specific surface area and typical porous structure are conducive to the rapid diffusion of lithium ions into the electrode, improving the lithium ion transfer rate. The macroporous structure retained during cycling serves as an expansion buffer space, reducing electrode pulverization and electrode structure damage, which can significantly improve cycle life and reversibility. Furthermore, the combination of phosphorus-doped P-Si and graphene oxide (GO) with excellent conductivity gives the material a large specific surface area and excellent mechanical flexibility. This not only effectively promotes electron and ion transport but also effectively helps to alleviate volume expansion during lithium ion insertion / extraction, maintains structural stability, and thus allows the reaction process to proceed more quickly and smoothly.

[0069] Preferably, the phosphorus-doped P-Si@GO heterostructure composite material prepared by the present invention has nanoscale, high purity and special morphological characteristics; the ultrathin phosphorus-doped P-Si nanosheets can provide Li+ with a large electrolyte / electrode contact area and a short diffusion path.

[0070] Preferably, this invention uses GO as the carbon source to achieve nanoscale composite coating of carbon materials. During the solvothermal process, phosphorus-doped P-Si crystals are grown in situ on the carbon material. Compared with traditional methods, the phosphorus-doped P-Si@GO heterostructure composite material synthesized using this method exhibits more stable cycling performance, effectively mitigating the volume effect of the material, inducing an internal electric field, promoting charge transfer, improving the electronic and ionic conductivity of the material, and ultimately enhancing the electrochemical performance of the material. Therefore, the phosphorus-doped P-Si@GO heterostructure composite material synthesized in this invention, when used as a lithium-ion battery electrode, exhibits high cycling stability.

[0071] An application of a phosphorus-doped P-Si@GO heterostructure composite material, wherein the phosphorus-doped P-Si@GO heterostructure composite material is used as a negative electrode material for lithium-ion batteries.

[0072] Preferably, the phosphorus-doped P-Si@RGO heterostructure composite material of the present invention, as a negative electrode material for lithium-ion batteries, overcomes the problems of large volume change of Si materials during Li+ insertion / extraction, resulting in weak electrical contact, poor capacity retention, and poor cycle stability, thereby improving the application performance of Si materials in lithium-ion batteries.

[0073] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a phosphorus-doped P-Si@RGO heterostructure composite material, characterized in that, Includes the following steps: S1. After etching the aluminum-silicon alloy with hydrochloric acid, P-Si material is obtained. Then, phosphorus source and organic compound are dissolved in ammonia water and mixed with P-Si to obtain solution A. Solution A is then surface-modified with APTES to obtain solution B. The organic compounds described in S1 include resorcinol, phenol, and hydroquinone; S2. Mix solution B and graphene oxide dispersion and add surfactant. After mixing evenly, solution D is obtained. S3. The D liquid is subjected to a hydrothermal reaction at room temperature, filtered to obtain a black precipitate, and the black precipitate is washed, dried and annealed at a heat preservation temperature to obtain the phosphorus-doped P-Si@RGO heterostructure composite material. The heat preservation temperature is 600℃-800℃ and the heat preservation atmosphere is Ar gas.

2. The method for preparing a phosphorus-doped P-Si@RGO heterostructure composite material as described in claim 1, characterized in that, The phosphorus source described in S1 includes sodium dihydrogen phosphate, sodium phosphate, phytic acid, or phosphoric acid.

3. The method for preparing a phosphorus-doped P-Si@RGO heterostructure composite material as described in claim 1, characterized in that, The surfactants described in S2 include CTAB or PVB.

4. The method for preparing a phosphorus-doped P-Si@RGO heterostructure composite material as described in claim 1, characterized in that, The hydrothermal reaction described in S3 is carried out at room temperature for 2 hours, and requires a settling time of 10 hours.

5. The method for preparing a phosphorus-doped P-Si@RGO heterostructure composite material as described in claim 1, characterized in that, The drying temperature described in S3 is 50-100℃, and the drying time is 8-24h.

6. The method for preparing a phosphorus-doped P-Si@RGO heterostructure composite material as described in claim 1, characterized in that, The heat preservation time mentioned in S3 is 2h-4h.

7. An application of a phosphorus-doped P-Si@RGO heterostructure composite material, wherein the phosphorus-doped P-Si@RGO heterostructure composite material is prepared by the method described in any one of claims 1 to 6, characterized in that, The phosphorus-doped P-Si@RGO heterostructure composite material is used as a negative electrode material for lithium-ion batteries.

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