A phosphorus-doped graphene-coated tin oxide nanoparticle composite material, a preparation method and applications thereof

Abstract

The application discloses a phosphorus-doped graphene-coated tin oxide nanoparticle composite material and a preparation method and application thereof. The P-Sn6O4(OH)4@RGO composite material is prepared by the following method: graphene oxide is dispersed into a mixed solution composed of ethanol and water, then a tin salt is added and ultrasonic dispersion is carried out to obtain a dispersion liquid; a reducing agent solution is added drop by drop into the dispersion liquid and is uniformly stirred, reaction is carried out for 0.5-2 hours, after reaction, the precipitate is separated by centrifugal washing, the precipitate is freeze-dried to obtain Sn@RGO; Sn@RGO and red phosphorus are added into ethylenediamine, and stirring is carried out to obtain a mixture; the mixture is subjected to a solvothermal reaction, the product after reaction is washed and dried to obtain the composite material. The cycle performance and rate performance of the composite material prepared by the application are greatly improved, the composite material can be stably cycled for 1450 cycles under a current density of 1.0 Ag ‑1 , and the capacity can be maintained at 970.0 mAhg ‑1 .

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of preparation of lithium ion battery negative electrode materials, and particularly relates to a phosphorus-doped graphene-coated tin oxide nanoparticle composite material and a preparation method and application thereof. BACKGROUND

[0002] The emergence of secondary batteries, particularly lithium ion batteries (LIBs), has reduced the burden of fossil fuel consumption. Currently, LIBs are widely used in all aspects of people's life, greatly changing people's way of life and making an important contribution to green life. However, in order to meet the demand for higher energy density, it is urgent to solve the problem of low electrode capacity of the current graphite-based negative electrode (372 mAh g -1 ). Among numerous candidate materials, Sn-based oxide electrodes have attracted much attention due to their high energy storage capacity. However, Sn-based oxide electrode materials exhibit severe volume expansion and rapid capacity decay during energy storage, which seriously hinders the practical application of Sn-based electrode materials.

[0003] Patent CN105226246A discloses a graphene-coated P@SnO2 core-shell quantum dot electrode material, a preparation method and application thereof. It selects graphene-coated P@SnO2 core-shell quantum dot electrode material, which is amorphous P-coated SnO2 quantum dots into a core-shell structure, and the core-shell structure is uniformly distributed on the graphene. The size of the core-shell structure is 2-10 nm. It adopts a hydrothermal method to coat P on the surface of SnO2 quantum dots, which can play a role as a buffer layer to protect the structure of SnO2 from being damaged during charging and discharging. At the same time, the carbon bond between P and graphene further ensures the stability of the structure, and at the same time improves the ion / electron transport capacity of the material, reduces the diffusion path, and effectively improves the cycle stability of the electrode material. However, the graphene-coated P@SnO2 core-shell quantum dot electrode material prepared by it has an irregular structure, and can only be stably cycled for 700 cycles at a current density of 1.0 Ag -1 . -1 .

[0004] The structural design of electrode materials is crucial to improve the electrochemical performance, and how to construct a suitable structure to ensure that the electrode material obtains high capacity while being stably cycled is a key problem to be solved at present. SUMMARY

[0005] The present application aims at providing a phosphorus-doped graphene-coated tin oxide nanoparticle composite material, a preparation method and application thereof. The present application adopts a reduction method assisted freeze-drying method to prepare a graphene-coated tin nanoparticle (Sn@RGO) composite material, and then adopts a solvothermal method to perform phosphorization treatment by taking red phosphorus as a phosphorus source and ethylenediamine as a solvent, to obtain a P-Sn6O4(OH)4@RGO composite material. The nanomaterial with a graphene-coated synergistic crystalline / amorphous structure prepared by the method can effectively inhibit the volume expansion of Sn6O4(OH)4 when applied to a lithium ion battery negative electrode, improve the conductivity of the electrode material, and exhibit high charge / discharge specific capacity, good rate performance and large-rate long cycle stability.

[0006] In a first aspect of the present application, a P-Sn6O4(OH)4@RGO composite material is provided, which is prepared by the following method:

[0007] (1) dispersing graphene oxide into a mixed solution composed of ethanol and water, then adding a tin salt and ultrasonically dispersing for 10-60 min to obtain a dispersion liquid;

[0008] (2) adding a reducing agent solution drop by drop into the dispersion liquid and stirring uniformly, reacting for 0.5-2 h, after the reaction, centrifugally washing and separating the precipitate, freeze-drying the precipitate to obtain Sn@RGO;

[0009] (3) adding Sn@RGO obtained in step (2) and red phosphorus into ethylenediamine, stirring for 8-20 h after ultrasonic treatment, to obtain a mixture; performing a solvothermal reaction on the mixture, washing and drying the product after the reaction to obtain a P-Sn6O4(OH)4@RGO composite material.

[0010] Preferably, in step (1), the volume ratio of ethanol to water in the mixed solution is (1-4):(1-3); the tin salt is SnCl2·2H2O, and the adding amount ratio of graphene oxide, SnCl2·2H2O and the mixed solution is (2-4 mg):(10-55 mg):(3-5 ml).

[0011] Preferably, in step (2), the reducing agent solution is composed of NaBH4, ethanol and water in a ratio of (25-125 mg):(12.5-25 ml):(25-37.5 ml).

[0012] Preferably, in step (2), the freeze-drying temperature is -80℃, and the time is 12 h.

[0013] Preferably, in step (2), the centrifuge speed during centrifugal washing is 5000-8000 rpm; and the centrifugal washing time is 3-10 min.

[0014] As preferred, in step (3), the ratio of the adding amount of Sn@RGO, red phosphorus and ethylenediamine is 0.16g:(0.02-0.1g):30ml.

[0015] As preferred, in step (3), the temperature of the solvothermal reaction is 180-200℃, and the reaction time is 35h-45h.

[0016] As preferred, in step (3), the drying condition is: drying at 60℃ for 12h.

[0017] As preferred, in step (1), the graphene oxide is prepared by the following method:

[0018] The graphite powder, sulfuric acid with a mass concentration of 98% and sodium nitrate are uniformly ultrasonically dispersed to obtain a mixture; potassium permanganate is added to the mixture, deionized water and hydrogen peroxide with a concentration of 30% are added drop by drop after uniform stirring, and then the brown mixture obtained after stirring for 50-70h is washed and centrifuged to obtain graphene oxide.

[0019] As preferred, the ratio of the adding amount of graphite powder, concentrated sulfuric acid, sodium nitrate, potassium permanganate, deionized water and hydrogen peroxide is: (2.5-7.5g):(60-180ml):(2-5g):(8-25g):(80-250ml):(25-75ml).

[0020] As preferred, when washing, deionized water (H2O) is used for multiple times of washing until the pH value approaches 7; when centrifuging, the centrifuge speed is 8000-12000rpm.

[0021] In the second aspect of the present application, the application of the above-mentioned P-Sn6O4(OH)4@RGO composite material in the preparation of lithium ion battery negative electrode material is provided.

[0022] The beneficial effects of the present application are:

[0023] 1. The preparation method of the present application is a high-efficiency and fast preparation method to obtain P-Sn6O4(OH)4@RGO with structure modification of crystalline / amorphous state, and the prepared material particles are uniformly distributed and completely coated by graphene, and the obtained negative electrode material has excellent rate performance and long cycle performance. Compared with the previously reported graphene-coated P@SnO2 core-shell quantum dot electrode material, the cycle performance and rate performance of the P-Sn6O4(OH)4@RGO composite material are greatly improved, and the capacity can be maintained at 970.0mA h g -1 at a current density of 1.0A g -1Compared with the reported graphene-coated P@SnO2 core-shell quantum dot electrode material, the P-Sn6O4(OH)4@RGO has a significantly improved large-rate performance, and the graphene-coated P@SnO2 core-shell quantum dot electrode material can provide a rate capacity of only 402mA hg -1 at a current density of 1.0A g -1

[0024] 2. The present application uses ethylenediamine instead of ethanolamine, which can improve the solubility of phosphorus during the solvothermal reaction, facilitate the modification of the material structure, and more easily prepare a crystalline / amorphous structure and a more regular nano-material structure.

[0025] 3. The present application has an advanced design concept, uses a crystalline / amorphous composite structure to improve the active sites and structural stability of the electrode material, and cooperates with phosphorus doping and a three-dimensional graphene coating structure to improve the energy storage performance of the electrode material. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 : XRD patterns of P-Sn6O4(OH)4@RGO and Sn@RGO nanocomposites prepared in Example 1;

[0027] Figure 2 : Microstructure and structure diagrams of Sn@RGO and P-Sn6O4(OH)4@RGO composites prepared in Example 1;

[0028] Figure 3 : EDS element distribution diagram and EDS spectrum diagram of P-Sn6O4(OH)4@RGO composite material prepared in Example 1;

[0029] Figure 4 : P2p and C1s XPS high-resolution spectrum of P-Sn6O4(OH)4@RGO composite material prepared in Example 1;

[0030] Figure 5 : Electrochemical performance diagrams of Sn@RGO and P-Sn6O4(OH)4@RGO composites prepared in Example 1;

[0031] Figure 6 : Large-rate long-cycle performance diagram of P-Sn6O4(OH)4@RGO composite material prepared in Example 1. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0033] ​In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in conjunction with specific embodiments.

[0034] The test materials used in the embodiments of the present application are all conventional test materials in the art and can be purchased through commercial channels.

[0035] Example 1: Preparation of P-Sn6O4(OH)4@RGO composite material

[0036] (1) Preparation of graphene oxide:

[0037] 5g of graphite powder was added to a round-bottom flask containing 120ml of concentrated sulfuric acid with a mass concentration of 98% and 2.5g of sodium nitrate, and after stirring and mixing uniformly, ultrasonic dispersion was performed for 30min, wherein the ultrasonic power was 180W and the ultrasonic frequency was 40KHz, to obtain a uniform mixture;

[0038] After stirring for a period of time, 15g of potassium permanganate was slowly added to the above mixture, and stirring was performed for 24h to disperse uniformly, and then 150ml of deionized water and 50ml of hydrogen peroxide with a concentration of 30% were added dropwise under ice water bath conditions, respectively, and then mechanical stirring was performed for 60h;

[0039] Subsequently, the obtained brownish mixture was washed with deionized water multiple times until the pH value approached 7, there was no floating impurity on the surface of the liquid, and the target product graphene oxide (GO) was obtained by centrifugation at a centrifuge speed of 8000rpm for 3min.

[0040] (2) Preparation of Sn@RGO:

[0041] 40mg of the above-obtained graphene oxide (GO) was taken and added to a mixed solution of 50ml of ethanol and water (V 乙醇 :V 水 =2:3), ultrasonic dispersion was performed for 10min, then 450mg of SnCl2·2H2O was added and ultrasonic dispersion was performed for 30min, wherein the ultrasonic power was 180W and the ultrasonic frequency was 40KHz, finally, 50mL of an ethanol and water mixed solution (V 乙醇 :V 水 =2:3) containing 100mg of NaBH4 was added dropwise to the above mixed solution and stirred uniformly, and the reaction was performed for 1h;

[0042] Finally, the precipitate was washed and separated multiple times by centrifugation at a centrifuge speed of 6000rpm for 5min, and freeze-dried at -80℃ for 12h, to obtain the product Sn@RGO.

[0043] (3) Preparation of P-Sn6O4(OH)4@RGO composite material:

[0044] Take 0.16g of the Sn@RGO material prepared above and 0.08g of red phosphorus into a beaker containing 30ml of ethylenediamine, and ultrasonic treatment the mixture under the condition of ultrasonic power of 180W and ultrasonic frequency of 40KHz for 30min and stirring for 12h; then, transfer the mixture into a polytetrafluoroethylene-lined autoclave and carry out a solvothermal reaction at 200℃ for 40h;

[0045] Finally, collect the product and wash it with water and ethanol for 3 times in turn, and then dry it in a vacuum oven at 60℃ for 12h to obtain the P-Sn6O4(OH)4@RGO nanocomposite.

[0046] Example 2: Preparation of P-Sn6O4(OH)4@RGO composite material

[0047] (1) Preparation of graphene oxide:

[0048] Add 5g of graphite powder into a round-bottom flask containing 120ml of concentrated sulfuric acid and 2.5g of sodium nitrate, and ultrasonic dispersion the mixture after stirring for 30min, wherein the ultrasonic power is 180W and the ultrasonic frequency is 40KHz, to obtain a uniform mixture;

[0049] After stirring for a period of time, slowly add 15g of potassium permanganate into the above mixture, and stir for 24h to disperse uniformly, and then add 150ml of deionized water and 50ml of 30% hydrogen peroxide solution into the mixture drop by drop under ice water bath condition, and then mechanically stir for 60h;

[0050] Then wash the obtained brown mixture with deionized water until the PH value approaches 7, and the liquid surface is free of floating impurities, and centrifuge the mixture at a speed of 8000rpm for 3min to obtain the target product graphene oxide (GO).

[0051] (2) Preparation of Sn@RGO:

[0052] Take 40mg of the graphene oxide (GO) obtained above into a mixed solution containing 50ml of ethanol and water (V 乙醇 :V 水 =2:3), ultrasonic dispersion for 10min, and then add 100mg of SnCl2·2H2O and ultrasonic dispersion for 30min, wherein the ultrasonic power is 180W and the ultrasonic frequency is 40KHz, and finally add 50ml of ethanol and water mixed solution (V 乙醇 :V 水 =2:3) containing 25mg of NaBH4 into the above mixture drop by drop and stir uniformly, and react for 1h;

[0053] Finally, the product Sn@RGO was obtained by washing the precipitate several times with centrifugation at 6000 rpm for 5 min and freeze-drying at -80 °C for 12 h.

[0054] (3) Preparation of P-Sn6O4(OH)4@RGO composite:

[0055] Take 0.16 g of the Sn@RGO material prepared above and 0.02 g of red phosphorus into a beaker containing 30 mL of ethylenediamine, and ultrasonically treat the mixture under the condition of ultrasonic power of 180 W and ultrasonic frequency of 40 KHz for 30 min and stir for 12 h; then, transfer the mixture into a polytetrafluoroethylene-lined autoclave and perform a solvothermal reaction at 180 °C for 35 h.

[0056] Finally, collect the product and wash it with water and ethanol for 3 times in sequence, and then dry it in a vacuum oven at 60 °C for 12 h to obtain the P-Sn6O4(OH)4@RGO nanocomposite.

[0057] Example 3: Preparation of P-Sn6O4(OH)4@RGO composite

[0058] (1) Preparation of graphene oxide:

[0059] Add 5 g of graphite powder into a round-bottom flask containing 120 ml of concentrated sulfuric acid and 2.5 g of sodium nitrate, and ultrasonically disperse the mixture for 30 min after stirring to obtain a uniform mixture, wherein the ultrasonic power is 180 W and the ultrasonic frequency is 40 KHz.

[0060] After stirring for a period of time, slowly add 15 g of potassium permanganate to the above mixture, and stir for 24 h to disperse uniformly, and then add 150 ml of deionized water and 50 ml of 30% hydrogen peroxide dropwise under ice water bath condition, respectively, and then mechanically stir for 60 h.

[0061] Subsequently, wash the obtained brown mixture with deionized water for several times until the PH value approaches 7 and there is no floating impurity on the surface of the liquid, and centrifuge at 8000 rpm for 3 min to obtain the target product graphene oxide (GO).

[0062] (2) Preparation of Sn@RGO:

[0063] Take 40 mg of the graphene oxide (GO) obtained above into a mixed solution containing 50 ml of ethanol and water (V 乙醇 :V 水=2:3), ultrasonically disperse for 10 min, then add 550 mg of SnCl2·2H2O and ultrasonically disperse for 30 min, wherein the ultrasonic power is 180 W and the ultrasonic frequency is 40 kHz. Finally, 50 mL of a mixture of ethanol and water containing 125 mg of NaBH4 (V 乙醇 :V 水 =2:3) Add dropwise to the above mixed solution and stir until homogeneous, react for 1 hour;

[0064] Finally, the precipitate was washed and separated by centrifugation at 6000 rpm for 5 minutes, and then freeze-dried at -80℃ for 12 hours to obtain the product Sn@RGO.

[0065] (3) Preparation of P-Sn6O4(OH)4@RGO composite material:

[0066] Take 0.16g of the Sn@RGO material prepared above and 0.1g of red phosphorus and add them to a beaker containing 30mL of ethylenediamine. Sonicate the mixture for 30min under ultrasonic power of 180W and ultrasonic frequency of 40KHz and stir for 12h. Then, transfer the mixture to a polytetrafluoroethylene-lined autoclave and carry out a solvothermal reaction at 190℃ for 45h.

[0067] Finally, the product was collected and washed three times with water and ethanol in sequence, and then dried in a vacuum oven at 60°C for 12 hours to obtain the P-Sn6O4(OH)4@RGO nanocomposite material.

[0068] Test case

[0069] 1. XRD analysis:

[0070] A Bruker D8 Advance X-ray diffractometer (Cu target) was used. )Analysis of the XRD patterns of the P-Sn6O4(OH)4@RGO and Sn@RGO nanocomposites prepared in Example 1 ( Figure 1 ).

[0071] By comparing with the standard card, it can be found that Sn@RGO nanocomposite material can be successfully converted into P-Sn6O4(OH)4@RGO nanocomposite material through Example 1.

[0072] 2. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis

[0073] The micro-morphology and structure of the Sn@RGO and P-Sn6O4(OH)4@RGO composite materials prepared in Example 1 were analyzed by a JEOL JSM-7800F field emission scanning electron microscope (SEM) and a JEOL JEM-2100plus transmission electron microscope (TEM), Figure 2 (a) is a SEM morphology diagram of Sn@RGO; Figure 2 (b) is a SEM morphology diagram of P-Sn6O4(OH)4@RGO composite material; Figure 2 (c) is a TEM image of P-Sn6O4(OH)4@RGO composite material; Figure 2 (d) is a HRTEM image of P-Sn6O4(OH)4@RGO composite material.

[0074] It can be found from the SEM diagram that the nano-material P-Sn6O4(OH)4@RGO particles prepared by phosphating modification are uniformly distributed and completely coated by graphene. The TEM image further shows that the P-Sn6O4(OH)4@RGO composite material nanoparticles have a diameter of about 50-100 nm. The HRTEM test results show that the phosphating treatment can induce the formation of a crystal / amorphous mixed structure inside the nano-material, which is beneficial to increase the active sites of the electrode material and improve the structural stability of the electrode material, thereby improving the energy storage performance of the electrode material.

[0075] 3. EDS element distribution and EDS spectrum analysis

[0076] The P-Sn6O4(OH)4@RGO composite material prepared in Example 1 was analyzed by a spectrometer online with a JEOL JSM-7800F scanning electron microscope, Figure 3 (a) is an EDS element distribution diagram of P-Sn6O4(OH)4@RGO composite material, and Figure 3 (b) is an EDS spectrum diagram of P-Sn6O4(OH)4@RGO composite material.

[0077] From Figure 3 It can be seen that the test results show that the elements Sn, P, C and O are uniformly distributed in the material, indicating that the phosphorus element is successfully introduced.

[0078] 4. P2p and C1s XPS high-resolution spectrum analysis

[0079] The P-Sn6O4(OH)4@RGO composite material prepared in Example 1 was analyzed by a ThermoFisher ESCALAB 250 (aluminum target), Figure 4 (a) and Figure 4 (b) are high-resolution XPS spectra of P2p and C1s of P-Sn6O4(OH)4@RGO composite material, respectively.Figure 4 The presence of P-Sn bond in a and P-C bond in 4b proves the successful introduction of phosphorus element.

[0080] 5. Electrochemical performance test

[0081] The electrode slurry was mixed by adding an appropriate amount of N-methyl-2-pyrrolidone (NMP) solvent to mix 80% active material, 10% acetylene black and 10% polyvinylidene fluoride. The mixed slurry was evenly coated on the copper foil cleaned with alcohol using a coater, and vacuum dried at 110°C for 12h using a vacuum oven after pre-drying. The electrolyte used was 1M LiPF6, with EC:DMC:EMC (1:1:1, wt%), containing 2.0% FEC. Then pure lithium metal sheet was used as the counter electrode using polypropylene film (Celgard 2320) as the separator. The 2032 type button cell was assembled in an Ar-filled glove box (oxygen and moisture less than 1 ppm), using metal spring and gasket. Charge-discharge test was carried out using NEWARE battery measurement system, with the cut-off voltage range of 3V to 0.01V, and the specific capacity obtained was calculated based on the total mass of the active material. Among them, the active material was selected as P-Sn6O4(OH)4@RGO and Sn@RGO nanocomposites prepared in Example 1.

[0082] Figure 5 The electrochemical performance graph of Sn@RGO and P-Sn6O4(OH)4@RGO composite prepared in Example 1. From the cycle performance test graph Figure 5 a), it can be seen that the reversible capacity of Sn@RGO is higher than that of P-Sn6O4(OH)4@RGO during the initial cycle process, and as the cycle proceeds, the capacity of Sn@RGO rapidly decays, while the reversible capacity of P-Sn6O4(OH)4@RGO gradually rises and tends to be stable, and after 200 cycles, the reversible capacity of P-Sn6O4(OH)4@RGO is 928mA h g -1 , which is significantly higher than the reversible capacity of Sn@RGO (550mA h g -1 ). From the rate performance test graph Figure 5 b), it can be seen that P-Sn6O4(OH)4@RGO can provide 802.0, 633.1, 542.3, 480.4, 385.7, 284.2 and 159.9mA h g -1 at current densities of 0.2, 0.5, 1.0, 2.0, 5.0, 10.0, 20.0A g -1discharge specific capacity, the specific capacity of P-Sn6O4(OH)4@RGO is lower than that of Sn@RGO at low current density, because the high conductivity of Sn is more conducive to the storage of lithium ions during the initial cycle, while the specific capacity of P-Sn6O4(OH)4@RGO is significantly higher than that of Sn@RGO at high current density, especially at 10.0 A g -1 and 20.0 A g -1 current density, P-Sn6O4(OH)4@RGO can provide a discharge specific capacity of 284.2 and 159.9 mA h g -1 , respectively, while Sn@RGO can only provide a reversible capacity of 122.8 and 52.4 mA h g -1 . When the current density returns to 0.2 A g -1 , although Sn@RGO can provide an average reversible capacity of 881.4 mA h g -1 , the capacity gradually decreases, indicating that the structure of the Sn@RGO electrode is damaged after high-rate testing, while P-Sn6O4(OH)4@RGO can stably provide an average reversible capacity of 601.0 mA h g -1 , and the capacity gradually increases, which indicates that the mixed crystalline / amorphous structure induced by phosphorization and the graphene coating structure significantly enhance the large-rate cycle stability of the electrode material, which is consistent with the cycle performance in a. Figure 5 Compared with the graphene-coated P@SnO2core-shell quantum dot electrode material reported in the prior art, the large-rate performance of P-Sn6O4(OH)4@RGO is significantly improved, and the graphene-coated P@SnO2core-shell quantum dot electrode material can only provide a rate capacity of 402 mA h g -1 (see CN 105226246B) at 1.0 A g -1 current density.

[0083] Figure 6 The large-rate long cycle performance of the P-Sn6O4(OH)4@RGO composite material prepared in Example 1 is stable, the reversible capacity is good, the coulombic efficiency is close to 100%, and the charge and discharge specific capacities are basically coincident during the charge and discharge process. As can be seen from the above Figure 6 , P-Sn6O4(OH)4@RGO can be stably cycled at 1.0 A g -1 current density for 1450 cycles, and the capacity can be maintained at 970.0 mA h g -1 , while the graphene-coated P@SnO2core-shell quantum dot electrode material reported in the prior art can only be stably cycled at 1.0 A g -1 current density for 700 cycles, and the capacity is only 271.0 mA h g -1(see CN 105226246 B), the results show that the P-Sn6O4(OH)4@RGO composite prepared by phosphating induction has better electrochemical performance, and the graphene-coated structure and the mixed structure of crystalline / amorphous can significantly improve the large rate and long cycle performance of the electrode material.

[0084] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Various modifications and changes can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A P-Sn6O4(OH)4@RGO composite material, characterized in that, It is prepared by the following method: (1) Graphene oxide is dispersed in a mixed solution of ethanol and water, and then tin salt is added and ultrasonically dispersed for 10-60 min to obtain a dispersion. (2) Add the reducing agent solution dropwise to the dispersion and stir until homogeneous. React for 0.5-2 hours. After the reaction, centrifuge and wash to separate the precipitate. Freeze-dry the precipitate to obtain Sn@RGO. (3) Sn@RGO and red phosphorus obtained in step (2) are added to ethylenediamine, ultrasonically treated and stirred for 8-20 h to obtain a mixture; the mixture is subjected to a solvothermal reaction, and the product after reaction is washed and dried to obtain P-Sn6O4(OH)4@RGO composite material.

2. The P-Sn6O4(OH)4@RGO composite material according to claim 1, characterized in that, In step (1), the volume ratio of ethanol to water in the mixed solution is (1-4):(1-3).

3. The P-Sn6O4(OH)4@RGO composite material according to claim 2, characterized in that, The tin salt is SnCl2·2H2O, and the ratio of the amount of graphene oxide, SnCl2·2H2O and the mixed solution added is (2-4 mg): (10-55 mg): (3-5 ml).

4. The P-Sn6O4(OH)4@RGO composite material according to claim 1, characterized in that, In step (2), the reducing agent solution is composed of NaBH4, ethanol and water in the ratio of (25-125mg): (12.5-25ml): (25-37.5ml).

5. The P-Sn6O4(OH)4@RGO composite material according to claim 1, characterized in that, In step (2), the freeze-drying temperature is -80℃ and the time is 12h.

6. The P-Sn6O4(OH)4@RGO composite material according to claim 1, characterized in that, In step (3), the ratio of Sn@RGO, red phosphorus and ethylenediamine added is 0.16g:(0.02-0.1g):30ml.

7. The P-Sn6O4(OH)4@RGO composite material according to claim 1, characterized in that, In step (3), the temperature of the solvothermal reaction is 180-200℃ and the reaction time is 35h-45h.

8. The P-Sn6O4(OH)4@RGO composite material according to claim 1, characterized in that, In step (1), the graphene oxide is prepared by the following method: Graphite powder, 98% sulfuric acid, and sodium nitrate were ultrasonically dispersed to obtain a mixture. Potassium permanganate was added to the mixture, and after stirring, deionized water and 30% hydrogen peroxide were added dropwise. The mixture was then stirred for 50-70 hours to obtain a brownish-red mixture. After washing, graphene oxide was obtained by centrifugation.

9. The P-Sn6O4(OH)4@RGO composite material according to claim 8, characterized in that, The ratio of graphite powder, concentrated sulfuric acid, sodium nitrate, potassium permanganate, deionized water and hydrogen peroxide is: (2.5-7.5g):(60-180ml):(2-5g):(8-25g):(80-250ml):(25-75ml).

10. The application of the P-Sn6O4(OH)4@RGO composite material according to any one of claims 1-9 in the preparation of lithium-ion battery anode materials.

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