Tin disulfide / graphene oxide / carbon nanotube composite material, method for preparing same, and use thereof

Abstract

The application discloses a tin disulfide / graphene oxide / carbon nanotube composite material and a preparation method and application thereof. The preparation method comprises the following steps: dispersing graphene oxide and carbon nanotubes in deionized water to prepare a dispersion liquid; dissolving SnCl2.2H2O crystals in the dispersion liquid, performing water bath reaction, and performing suction filtration to prepare a mixed liquid; adding a polyvinyl alcohol solution into the mixed liquid, rapidly freezing for 4-6 hours through liquid nitrogen, and then performing freeze drying; sintering under nitrogen protection at 550-650 DEG C to prepare the tin disulfide / graphene oxide / carbon nanotube composite material; adding sulfur sublimation powder into the tin disulfide / graphene oxide / carbon nanotube composite material, uniformly blending through ball milling to obtain sulfur-doped powder; and reacting the sulfur-doped powder under nitrogen protection at 400-500 DEG C and keeping warm. The application has the advantages of low production cost, high safety, good dispersion effect, and improved conductivity and cycle stability of the material as a negative electrode of a lithium ion battery.

Description

TECHNICAL FIELD

[0001] The application belongs to composite materials and its preparation method, and particularly to a tin disulfide / graphene oxide / carbon nanotube composite material and its preparation method and application. BACKGROUND

[0002] In lithium ion batteries, SnS2 realizes effective lithium ion intercalation and deintercalation by generating intermediate compounds and metal tin, and exhibits a mass specific capacity (about 645 mAh / g) far exceeding that of graphite negative electrodes. However, the large volume expansion rate and low electronic conductivity of SnS2 seriously restrict the maintenance of its cycle stability and the enhancement of its rate performance during charging and discharging.

[0003] Therefore, many works have combined SnS2 with graphene and carbon nanotubes to buffer the volume expansion of sulfides by the flexible structure of carbon materials and to enhance the overall conductivity of the electrode and improve the rate performance of the battery by the high conductivity of carbon materials. However, the common material compounding methods at present are: (1) a solvothermal method involving reducing graphene oxide and tin sulfide sources under high temperature and high pressure conditions to generate a composite material; and (2) a chemical vapor deposition method for depositing SnS2 nanomaterials on the surface of graphene to realize material compounding through a complex CVD process. These compounding methods have complex physical and chemical processes, are difficult to produce, have poor safety, are high in cost, and need to be further improved in mixing uniformity. SUMMARY

[0004] The application aims to overcome the deficiencies in the prior art, provide a preparation method of a tin disulfide / graphene oxide / carbon nanotube composite material which is simple in process, high in safety and can be produced on a large scale, provide a tin disulfide / graphene oxide / carbon nanotube composite material which is good in conductivity and cycle stability, and provide an application of the tin disulfide / graphene oxide / carbon nanotube composite material in lithium ion battery electrodes.

[0005] The application provides a preparation method of a tin disulfide / graphene oxide / carbon nanotube composite material.

[0006] Step one, dispersing graphene oxide and carbon nanotubes in deionized water to obtain a dispersion liquid;

[0007] Step two, dissolving SnCl2·2H2O crystals in the dispersion liquid, performing water bath reaction, and performing suction filtration to obtain a mixed liquid;

[0008] Step three, adding a polyvinyl alcohol (PVA) solution to the mixed liquid, rapidly freezing for 4-6 hours through liquid nitrogen, and then freeze-drying for 72-100 hours;

[0009] Step four, sintering under nitrogen protection at 550~650℃ to obtain the SnO2 / graphene oxide / carbon nanotube composite material;

[0010] Step five, adding sublimed sulfur powder to the SnO2 / graphene oxide / carbon nanotube composite material, and ball-milling and blending uniformly to obtain a sulfur-doped powder;

[0011] Step six, reacting the sulfur-doped powder under nitrogen protection at 400~500℃ to obtain a SnS2 / graphene oxide / carbon nanotube composite material.

[0012] Further, in step one, the mass ratio of graphene oxide, carbon nanotube and deionized water is 1~10:1:1000~10000. The dispersion is carried out every 2 hours of stirring and 30 minutes of ultrasonic treatment, and the process is repeated at least 10 times. The dispersion of the dispersion medium in the dispersion liquid is not good when the dispersion concentration of graphene oxide and carbon nanotube is too high, and the stirring and ultrasonic treatment time is too short.

[0013] Further, in step two, the mass ratio of SnCl2·2H2O crystal and deionized water is 1~5:250. The water bath reaction temperature is 70~90℃.

[0014] Further, in step three, the volume ratio of PVA solution to mixed solution is 1:20~30. The mass concentration of the PVA solution is 10%.

[0015] Further, in step five, the mass ratio of sublimed sulfur powder to SnO2 / graphene oxide / carbon nanotube composite material is 3~8:1. The ball-milling speed is 200~300 rpm, and the time is 2~6 hours.

[0016] Further, in step six, the temperature of the heat preservation is 200~300℃, and the time is 6~10 hours. The crucible is not covered during the heat preservation process.

[0017] The SnS2 / graphene oxide / carbon nanotube composite material obtained by the preparation method of the SnS2 / graphene oxide / carbon nanotube composite material comprises SnS2nanosheets, graphene oxide and carbon nanotubes. The SnS2nanosheets are wrapped in the graphene and carbon nanotube clusters. The crucible is covered during the reaction at 400~500℃.

[0018] The SnS2 / graphene oxide / carbon nanotube composite material is applied to a lithium ion battery electrode.

[0019] Further, the method comprises the following steps: mixing and dispersing SnS2 / graphene oxide / carbon nanotube composite material, polyvinylidene fluoride and conductive carbon black in NMP, coating on the surface of a copper foil, and cutting to obtain an electrode foil for a lithium ion battery.

[0020] Preparation principle: the prepared SnS2 is nanosheet structure and is wrapped inside or attached to the surface of the carbon material. The introduction of PVA plays a thickening role in the dispersion liquid, which, together with the rapid freezing + freeze-drying operation, avoids the uneven composite of the material caused by the settlement of the dispersion liquid. In addition, the addition of PVA can also maintain the structure of the precursor during the freeze-drying process, avoiding the collapse of the structure. The uniform mixing of SnS2 in the carbon material improves the electronic conductivity of the material as an electrode material, and the structural toughness of the carbon material effectively buffers the volume expansion of SnS2 during the charging and discharging process, improving the overall cycle stability of the material.

[0021] Advantages: compared with the prior art, the present application has the following remarkable features:

[0022] 1. Low production cost and high safety, the whole process does not involve complex equipment and high pressure reaction, and the effective composite of the material is realized at normal pressure, which is convenient and practical and has the potential for large-scale production.

[0023] 2. Good dispersion effect, the uniform preparation of the composite material is realized through rapid freezing + freeze-drying operation, and the SnS2 nanosheet is effectively adhered to the surface of the carbon material or wrapped inside the carbon material.

[0024] 3. The carbon material and SnS2 are effectively combined to improve the conductivity and cycle stability of the material as a lithium ion battery negative electrode. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the XRD pattern of the tin disulfide / graphene oxide / carbon nanotube composite material of the present application;

[0026] Figure 2 is the SEM image of the product of example 1 of the present application;

[0027] Figure 3 is the TEM image of the product of example 1 of the present application;

[0028] Figure 4 is the SEM image of the product of example 2 of the present application;

[0029] Figure 5 is the TEM image of the product of example 2 of the present application;

[0030] Figure 6 is the SEM image of the product of example 3 of the present application;

[0031] Figure 7 is the TEM image of the product of example 3 of the present application;

[0032] Figure 8 is the SEM image of the product of example 4 of the present application;

[0033] Figure 9 This is a TEM image of the product obtained in Example 4 of the present invention. Detailed Implementation

[0034] Unless otherwise specified, all materials, reagents, and instruments used in the following examples are commercially available. Experimental methods not specifically described in the examples are generally performed under standard conditions or as recommended by the manufacturer.

[0035] Example 1

[0036] A method for preparing a SnS2 / graphene oxide / carbon nanotube composite material includes the following steps:

[0037] (1) Take 200 mg of graphene oxide and 50 mg of carbon nanotubes and disperse them in 250 ml of deionized water to prepare a dispersion. During the dispersion process, stir for 2 hours and sonicate for 30 minutes, repeating 10 times.

[0038] (2) Take 1.5 g of SnCl2·2H2O crystals and dissolve them in the dispersion. React them in a water bath at 90°C for 2 hours, and then filter them to remove impurities to prepare a mixed solution.

[0039] (3) Add 10 ml of 10% polyvinyl alcohol (PVA) solution to the mixture, then freeze it rapidly with liquid nitrogen for 4 hours, followed by freeze drying for 96 hours.

[0040] (4) The tin dioxide / graphene oxide / carbon nanotube composite material was prepared by sintering at 600℃ for 2 hours under high-purity nitrogen protection.

[0041] (5) Add sublimed sulfur powder (5 times the mass of the composite material) to the tin dioxide / graphene oxide / carbon nanotube composite material, and ball mill and mix at 250 rpm for 4 hours to obtain uniform sulfur-doped powder.

[0042] (6) The sulfur-doped powder was reacted at 400°C for 3 hours under nitrogen protection (the crucible was covered during the reaction) to prepare tin disulfide / graphene oxide / carbon nanotube composite material.

[0043] (7) Keep at 200°C for 6 hours in a nitrogen atmosphere to remove excess sulfur powder from the tin disulfide / graphene oxide / carbon nanotube composite material system.

[0044] like Figure 1 This indicates the successful synthesis of the tin disulfide crystal structure. Figures 2-3 Tin disulfide nanosheets are wrapped around graphene / carbon nanotube clusters at the micrometer scale.

[0045] Example 2

[0046] A preparation method of a SnS2 / graphene oxide / carbon nanotube composite material, comprising the following steps:

[0047] (1) 200 mg of graphene oxide and 50 mg of carbon nanotubes are dispersed in 250 ml of deionized water to prepare a dispersion liquid, and in the dispersion process, ultrasonic treatment is performed for 30 minutes every 2 hours of stirring, and the process is repeated 10 times.

[0048] (2) 2 g of SnCl2·2H2O crystals are dissolved in the dispersion liquid, and a water bath reaction is performed at 90°C for 2 hours, and then impurities are removed by suction filtration to prepare a mixed liquid.

[0049] (3) 10 ml of a polyvinyl alcohol (PVA) solution with a mass concentration of 10% is added to the mixed liquid, and then rapid freezing is performed by liquid nitrogen for 4 hours, followed by freeze-drying for 96 hours.

[0050] (4) Sintering is performed at 600°C for 2 hours under the protection of high-purity nitrogen to prepare a tin dioxide / graphene oxide / carbon nanotube composite material.

[0051] (5) Sublimed sulfur powder (5 times the mass of the composite material) is added to the tin dioxide / graphene oxide / carbon nanotube composite material, and ball milling is performed for 4 hours at 250 rpm to obtain a uniform sulfur-doped powder.

[0052] (6) The sulfur-doped powder is reacted at 400°C for 3 hours under the protection of nitrogen (the crucible is covered during the reaction), and a tin disulfide / graphene oxide / carbon nanotube composite material is prepared.

[0053] (7) Excess sulfur powder in the tin disulfide / graphene oxide / carbon nanotube composite material system is removed by heat treatment at 200°C for 6 hours in a nitrogen atmosphere.

[0054] As Figure 1 indicated, the tin disulfide crystal structure is successfully synthesized. As Figures 4-5 , the tin disulfide nanosheet is wrapped in the graphene / carbon nanotube mass in the micron scale.

[0055] Example 3

[0056] A preparation method of a SnS2 / graphene oxide / carbon nanotube composite material, comprising the following steps:

[0057] (1) 200 mg of graphene oxide and 50 mg of carbon nanotubes are dispersed in 250 ml of deionized water to prepare a dispersion liquid, and in the dispersion process, ultrasonic treatment is performed for 30 minutes every 2 hours of stirring, and the process is repeated 10 times.

[0058] (2) 2.5 g SnCl2·2H2O crystals were dissolved in the dispersion, and reacted in a water bath at 90°C for 2 hours, and then filtered to remove impurities, to prepare a mixed solution.

[0059] (3) 10 ml of a polyvinyl alcohol (PVA) solution with a mass concentration of 10% was added to the mixed solution, and then rapidly frozen by liquid nitrogen for 4 hours, followed by freeze-drying for 96 hours.

[0060] (4) The tin dioxide / graphene oxide / carbon nanotube composite material was prepared by sintering at 600°C for 2 hours under high-purity nitrogen protection.

[0061] (5) Sublimed sulfur powder (5 times the mass of the composite material) was added to the tin dioxide / graphene oxide / carbon nanotube composite material, and ball-milled and blended at 250 rpm for 4 hours to obtain a uniform sulfur-doped powder.

[0062] (6) The sulfur-doped powder was reacted at 400°C for 3 hours under nitrogen protection (the crucible was covered during the reaction), to prepare a tin disulfide / graphene oxide / carbon nanotube composite material.

[0063] (7) The excess sulfur powder in the tin disulfide / graphene oxide / carbon nanotube composite material system was removed by heating at 200°C for 6 hours under a nitrogen atmosphere.

[0064] As shown in FIG. 1, the successful synthesis of the tin disulfide crystal structure is indicated. Figure 1 As shown in FIG. 2, the tin disulfide nanosheet is wrapped in the graphene / carbon nanotube mass in the micron scale. Figures 6-7

[0065] Example 4

[0066] A method for preparing a SnS2 / graphene oxide / carbon nanotube composite material, comprising the following steps:

[0067] (1) 200 mg of graphene oxide and 50 mg of carbon nanotubes were dispersed in 250 ml of deionized water to prepare a dispersion, and in the dispersion process, ultrasonic treatment was performed for 30 minutes every 2 hours of stirring, and the process was repeated 10 times.

[0068] (2) 3 g of SnCl2·2H2O crystals were dissolved in the dispersion, and reacted in a water bath at 90°C for 2 hours, and then filtered to remove impurities, to prepare a mixed solution.

[0069] (3) 10 ml of a polyvinyl alcohol (PVA) solution with a mass concentration of 10% was added to the mixed solution, and then rapidly frozen by liquid nitrogen for 4 hours, followed by freeze-drying for 96 hours.

[0070] ​(4) The tin dioxide / graphene oxide / carbon nanotube composite material was prepared by sintering at 600℃ for 2 hours under high-purity nitrogen protection.

[0071] (5) Add sublimed sulfur powder (5 times the mass of the composite material) to the tin dioxide / graphene oxide / carbon nanotube composite material, and ball mill and mix at 250 rpm for 4 hours to obtain uniform sulfur-doped powder.

[0072] (6) The sulfur-doped powder was reacted at 400°C for 3 hours under nitrogen protection (the crucible was covered during the reaction) to prepare tin disulfide / graphene oxide / carbon nanotube composite material.

[0073] (7) Keep at 200°C for 6 hours in a nitrogen atmosphere to remove excess sulfur powder from the tin disulfide / graphene oxide / carbon nanotube composite material system.

[0074] like Figure 1 This indicates the successful synthesis of the tin disulfide crystal structure. Figures 8-9 Tin disulfide nanosheets are wrapped around graphene / carbon nanotube clusters at the micrometer scale.

[0075] Example 5

[0076] A method for preparing a SnS2 / graphene oxide / carbon nanotube composite material includes the following steps:

[0077] (1) Take 50 mg of graphene oxide and 50 mg of carbon nanotubes and disperse them in 50 ml of deionized water to prepare a dispersion. During the dispersion process, stir for 2 hours and sonicate for 30 minutes, repeating 10 times.

[0078] (2) Take 0.2 g of SnCl2·2H2O crystals and dissolve them in the dispersion. React them in a water bath at 70°C for 2 hours. Then filter to remove impurities and prepare a mixed solution.

[0079] (3) Add 2.5 ml of 10% polyvinyl alcohol (PVA) solution to the mixture, then freeze it rapidly with liquid nitrogen for 4 hours, followed by freeze drying for 96 hours.

[0080] (4) The tin dioxide / graphene oxide / carbon nanotube composite material was prepared by sintering at 550°C for 2 hours under high-purity nitrogen protection.

[0081] (5) Add sublimed sulfur powder (3 times the mass of the composite material) to the tin dioxide / graphene oxide / carbon nanotube composite material, and ball mill and mix at 200 rpm for 6 hours to obtain uniform sulfur-doped powder.

[0082] (6) The sulfur-doped powder is reacted at 450°C for 3 hours under nitrogen protection (the crucible is covered during the reaction process), to prepare a tin disulfide / graphene oxide / carbon nanotube composite material.

[0083] (7) The excess sulfur powder in the tin disulfide / graphene oxide / carbon nanotube composite material system is removed by heat preservation at 300°C for 8 hours under a nitrogen atmosphere.

[0084] Example 6

[0085] A preparation method of a SnS2 / graphene oxide / carbon nanotube composite material, comprising the following steps:

[0086] (1) 500 mg of graphene oxide and 50 mg of carbon nanotubes are dispersed in 500 ml of deionized water to prepare a dispersion liquid. During the dispersion process, ultrasonic treatment is performed for 30 minutes every 2 hours of stirring, and the process is repeated 10 times.

[0087] (2) 10 g of SnCl2·2H2O crystals are dissolved in the dispersion liquid, and a water bath reaction is performed at 80°C for 2 hours. Then, impurities are removed by suction filtration, to prepare a mixed liquid.

[0088] (3) 16.7 ml of a polyvinyl alcohol (PVA) solution with a mass concentration of 10% is added to the mixed liquid, and then the mixed liquid is rapidly frozen by liquid nitrogen for 4 hours, followed by freeze-drying for 96 hours.

[0089] (4) The tin dioxide / graphene oxide / carbon nanotube composite material is prepared by sintering at 650°C for 2 hours under high-purity nitrogen protection.

[0090] (5) Sublimed sulfur powder (with a mass 8 times that of the composite material) is added to the tin dioxide / graphene oxide / carbon nanotube composite material, and ball milling blending is performed at 300 rpm for 2 hours, to obtain a uniform sulfur-doped powder.

[0091] (6) The sulfur-doped powder is reacted at 450°C for 3 hours under nitrogen protection (the crucible is covered during the reaction process), to prepare a tin disulfide / graphene oxide / carbon nanotube composite material.

[0092] (7) The excess sulfur powder in the tin disulfide / graphene oxide / carbon nanotube composite material system is removed by heat preservation at 300°C for 8 hours under a nitrogen atmosphere.

[0093] Application Example 1

[0094] Accurately weigh 800 mg of SnS2 / graphene oxide / carbon nanotube composite prepared in Example 1, 100 mg of PVDF, and 100 mg of conductive carbon black, disperse in 4 mL of NMP, and magnetically stir for 24 h to obtain the desired electrode sheet. High-purity lithium sheet and microporous polyethylene (PE) film are used as the anode and separator of the battery. 1M LiPF6 is dissolved in a mixed solution of ethyl carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:1 as the electrolyte. The entire process of assembling the CR2032 button cell is carried out in an argon-filled glove box, and the water and oxygen concentrations in the glove box are controlled to be below 0.1 ppm. Each battery contains 100 microliters of electrolyte.

[0095] Application Example 2

[0096] Except that the SnS2 / graphene oxide / carbon nanotube composite is replaced by the material of Example 2, the remaining steps are the same as Application Example 1.

[0097] Application Example 3

[0098] Except that the SnS2 / graphene oxide / carbon nanotube composite is replaced by the material of Example 3, the remaining steps are the same as Application Example 1.

[0099] Application Example 4

[0100] Except that the SnS2 / graphene oxide / carbon nanotube composite is replaced by the material of Example 4, the remaining steps are the same as Application Example 1.

[0101] The lithium ion batteries obtained in Application Examples 1-4 are subjected to performance testing using a battery test system, and the test voltage window is 0-3 V. The results are shown in Table 1. The stable cycle number refers to the number of stable charge and discharge of the battery, and one cycle is completed for one charge or discharge process. The discharge capacity refers to the mass specific capacity of the battery after 100 charge and discharge cycles at a current density of 500 mA / g.

[0102] Table 1 Performance data of lithium ion batteries obtained in Application Examples 1-4

[0103] Cycle stability number of laps Discharge capacity (mAh / g) Application Example 1 100 561 Application Example 2 100 612 Application Example 3 100 557 Application Example 4 100 463

[0104] As can be seen from Table 1, the discharge capacity of the battery of Example 2 is the highest, and therefore, among the above examples, Example 2 is the optimal example.

[0105] Comparative Example 1

[0106] The rest of the steps of this comparative example are the same as those of Example 2, except that the mass concentration of PVA is replaced by 5%. The battery is prepared according to the method of Application Example 1, and it is found that the dispersion liquid is prone to sedimentation, and the macrostructure of the material collapses more obviously after freeze-drying. The battery has poor cycle stability during the cycle process.

[0107] Comparative Example 2

[0108] The rest of the steps of this comparative example are the same as those of Example 2, except that the mass concentration of PVA is replaced by 15%. The battery is prepared according to the method of Application Example 1, and it is found that PVA cannot be effectively dissolved in the system.

[0109] Comparative Example 3

[0110] The rest of the steps of this comparative example are the same as those of Example 2, except that PVA is replaced by sodium carboxymethyl cellulose (CMC). The battery is prepared according to the method of Application Example 1, and it is found that the dispersion effect of the dispersion liquid is close to that of the PVA system, but the macrostructure of the material collapses more obviously after freeze-drying. The battery has poor cycle stability during the cycle process.

[0111] Comparative Example 4

[0112] The rest of the steps of this comparative example are the same as those of Example 2, except that SnCl2·2H2O crystals are replaced by stannous acetate (Sn(CH3COO)2). The battery is prepared according to the method of Application Example 1, and it is found that it is difficult to dissolve during the preparation of the dispersion liquid, and the mass specific capacity of the material after being prepared as an electrode material is low.

[0113] Comparative Example 5

[0114] The rest of the steps of this comparative example are the same as those of Example 2, except that step (3) is replaced by: rapid freezing for 8 hours by liquid nitrogen, followed by freeze-drying for 48 hours. The battery is prepared according to the method of Application Example 1, and it is found that there is no obvious difference compared with the case in Application Example 1, but the test time is increased.

Claims

1. A method for preparing a tin disulfide / graphene oxide / carbon nanotube composite, characterized by, It comprises the following steps: Step one, take graphene oxide and carbon nanotubes dispersed in deionized water to prepare a dispersion; Step two, take SnCl2·2H2O crystals dissolved in the dispersion, water bath reaction, filtration, to prepare a mixed solution; Step three, add polyvinyl alcohol solution to the mixed solution, freeze rapidly for 4-6 hours by liquid nitrogen, and freeze-dry for 72-100 hours; Step four, sintering under nitrogen protection at 550-650℃ to prepare a tin dioxide / graphene oxide / carbon nanotube composite material; Step five, add sulfur powder to the tin dioxide / graphene oxide / carbon nanotube composite material, and ball mill to blend uniformly to obtain a sulfur-doped powder; Step six, react the sulfur-doped powder under nitrogen protection at 400-500℃ to obtain a tin disulfide / graphene oxide / carbon nanotube composite material; In step three, the volume ratio of PVA solution to mixed solution is 1:20-30; the mass concentration of the PVA solution is 10%; In step six, the temperature for heat preservation is 200-300℃, and the time is 6-10 hours to remove excess sulfur powder in the tin disulfide / graphene oxide / carbon nanotube composite material system.

2. The method for preparing a tin disulfide / graphene oxide / carbon nanotube composite material according to claim 1, characterized in that: In step one, the mass ratio of graphene oxide, carbon nanotubes, and deionized water is 1-10:1:1000-10000.

3. The method for preparing a tin disulfide / graphene oxide / carbon nanotube composite material according to claim 1, characterized in that: In step two, the mass ratio of SnCl2·2H2O crystals to deionized water is 1-5:

250.

4. The method for preparing a tin disulfide / graphene oxide / carbon nanotube composite material according to claim 1, characterized in that: In step two, the water bath reaction temperature is 70-90℃.

5. The method for preparing a tin disulfide / graphene oxide / carbon nanotube composite material according to claim 1, characterized in that: In step five, the mass ratio of sulfur powder to tin dioxide / graphene oxide / carbon nanotube composite material is 3-8:

1.

6. The method for preparing a tin disulfide / graphene oxide / carbon nanotube composite material according to claim 1, characterized in that: In step five, the ball milling speed is 200-300 rpm, and the time is 2-6 hours.

7. The tin disulfide / graphene oxide / carbon nanotube composite material obtained by the method according to any one of claims 1-6, characterized in that: It comprises tin disulfide nanosheets, graphene oxide, and carbon nanotubes, and the tin disulfide nanosheets are wrapped in the graphene and carbon nanotube clusters.

8. The application of a tin disulfide / graphene oxide / carbon nanotube composite material in lithium ion battery electrodes according to claim 7.

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