CN111799458A - A kind of tin element composite tungsten disulfide/reduced graphene oxide composite electrode material and its preparation method and application - Google Patents

Abstract

The invention discloses a tin element composite tungsten disulfide/reduced graphene oxide composite electrode material, a preparation method and application thereof, and belongs to the field of preparation of tungsten disulfide nanomaterials. The invention provides a simple and controllable method for preparing tin element composite tungsten disulfide/reduced graphene oxide composite electrode material: using solvothermal and normal temperature liquid phase reduction process, under the auxiliary action of template agent, in tungsten disulfide/reduced graphene oxide composite electrode material. Tin nanoparticles are grown on the tungsten disulfide nanosheets of the reduced graphene oxide composite material, and the electrical conductivity of the final tin element composite tungsten disulfide/reduced graphene oxide composite electrode material is effectively enhanced by tin element, thereby improving the electrochemical performance of the material. The tin element composite tungsten disulfide/reduced graphene oxide composite electrode material prepared by the present invention has good dispersibility, uniform size and uniform morphology, and after circulating for 200 cycles at a current density of 200 mA g ^-1 , its capacity retention rate is 92%, so it can be applied to battery anode materials.

Description

A kind of tin element composite tungsten disulfide/reduced graphene oxide composite electrode material and Preparation method and application thereof

technical field

The invention belongs to the field of preparation of tungsten disulfide nanomaterials, and relates to a tin element composite tungsten disulfide/reduced graphene oxide composite electrode material and a preparation method and application thereof.

Background technique

Due to the high energy density, long cycle life, green cleaning and other characteristics of sodium-ion batteries, it is one of the most important energy storage devices in the energy field. In the past ten years, scientists have continuously developed research on the performance improvement and improvement of sodium-ion batteries. Through continuous experimental adjustment and improvement, the performance of sodium-ion batteries has become more and more excellent. Transition metal sulfides have gradually become the focus of attention in the field of electrochemical research due to their high theoretical capacity and their excellent cycle characteristics and rate capability. Relatively traditional active materials for intercalation Na-ion batteries usually exist in the form of bulk, but the bulk is stacked by nano-layered structures. As a transition metal chalcogenide, tungsten disulfide (WS2) has abundant resources. The theoretical capacity is high and the electrode potential is high. It is a layered compound with a graphene-like structure. This unique layered structure and its large interlayer spacing (6.12nm) are conducive to the de-intercalation of sodium ions during charge and discharge. However, tungsten disulfide will deform greatly during the charging and discharging process, and the cycle performance is not ideal. As a semiconductor material, it has the disadvantage of poor electrical conductivity, resulting in slow electron transport and poor rate performance.

According to literature reports, the use of carbon materials as the matrix is conducive to the transport of electrons and can effectively improve the electrochemical stability of composite materials. For example, Jing Ren et al. used tungsten disulfide and three-dimensional single-wall carbon nanotube composites as anode materials for lithium-ion batteries (Ren J, Wang Z, Yang F, et al. Freestanding 3D single-wall carbon nanotubes/WS ₂ , nanosheets foams as ultra-long-life anodes for rechargeablelithium ion batteries[J].Electrochimica Acta, 2018.), which greatly improves the cycle stability of the material. It can cycle for 1000 cycles at a current density of 1A/g, and the capacity is stable at 688.9mAh/g . However, the poor conductivity of tungsten disulfide itself results in poor rate performance.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a tin elemental composite tungsten disulfide/reduced graphene oxide composite electrode material and a preparation method and application thereof. The present invention prepares the tin element composite tungsten disulfide/reduced graphene oxide composite electrode material through a simple preparation method. The tin simple substance composite tungsten disulfide/reduced graphene oxide composite electrode material prepared by the invention has good capacity retention rate and has great potential in the application of battery negative electrode.

In order to achieve the above object, the present invention adopts the following technical solutions to be realized:

The invention discloses a preparation method of tin element composite tungsten disulfide/reduced graphene oxide composite electrode material, comprising the following steps:

1) uniformly dispersing reduced graphene oxide, tungsten hexachloride and thioacetamide in water to obtain a reaction solution; cooling the reaction solution after hydrothermal reaction to obtain a product, and after centrifugal washing of the product, the powder is collected by freeze-drying , to obtain tungsten disulfide/reduced graphene oxide composite material;

2) adding polyvinylpyrrolidone, stannous chloride dihydrate, tungsten disulfide/reduced graphene oxide composite material and sodium borohydride to the water and uniformly dispersing to obtain a precursor liquid; after the centrifugal washing of the precursor liquid, the powder is collected by freeze-drying, A tin elemental composite tungsten disulfide/reduced graphene oxide composite material is obtained;

3) calcining and annealing the tin element composite tungsten disulfide/reduced graphene oxide composite material to obtain a tin element compound tungsten disulfide/reduced graphene oxide composite electrode material.

Preferably, in step 1), the reaction feed ratio of reduced graphene oxide, water, tungsten hexachloride and thioacetamide is (30-60) mg: (30-60) mL: (0.295-0.59) g: (0.5625～1.125) g.

Preferably, in step 1), the hydrothermal reaction temperature is 200-240° C., and the reaction time is 12-48 h.

Preferably, in step 2), the reaction feed ratio of polyvinylpyrrolidone, stannous chloride dihydrate, tungsten disulfide/reduced graphene oxide composite material, sodium borohydride and water is (1～4) mg: (1～4) mg 4) mg: (1 to 4) mg: (0.2 to 1) mg: (10 to 30) mL.

Preferably, in step 1) and step 2), the freeze-drying temperature is -40--70°C, the time is 8-12h, and the vacuum degree of the freeze-drying environment is 10-40Pa.

Preferably, the calcination and annealing treatment in step 3) specifically includes: under the protection of an inert atmosphere, the calcination temperature is 400-600° C., the heating rate is 5-20° C./min, and the temperature is kept for 1-3 hours.

The invention also discloses a tin element composite tungsten disulfide/reduced graphene oxide composite electrode material prepared by the above preparation method.

Preferably, the capacity retention rate of the tin element composite tungsten disulfide/reduced graphene oxide composite electrode material is 92% after being cycled for 200 cycles at a current density of 200 mA·g ⁻¹ .

The invention also discloses the application of using the above-mentioned tin simple substance composite tungsten disulfide/reduced graphene oxide composite electrode material as a battery negative electrode material.

Compared with the prior art, the present invention has the following beneficial effects:

The invention discloses a preparation method of a tin element composite tungsten disulfide/reduced graphene oxide composite electrode material. The preparation method utilizes a solvothermal method and a normal temperature liquid phase reduction process, and uses thioacetamide as a template under the auxiliary action of a template agent. The tin element composite tungsten disulfide/reduced graphene oxide (Sn@WS ₂ /rGO) composite material was prepared, and then the composite material was calcined and annealed, and the tin element composite tungsten disulfide/reduced graphene oxide (Sn@WS 2 /rGO) composite was successfully prepared. WS ₂ /rGO) composite electrode material. In the preparation method, tungsten disulfide nanosheets are grown on the reduced graphene oxide structure by a simple solvothermal method, and a method with easily controllable parameters and mild process is used by adopting a normal temperature liquid phase reduction process and the assistance of a template agent. , on the tungsten disulfide nanosheets of tungsten disulfide/reduced graphene oxide (WS ₂ /rGO) composite material, tin nano-particles are reduced and grown, using the strong electrical conductivity of tin metal to make the composite material have a higher theoretical basis capacity, which can effectively enhance the conductivity of the final composite electrode material, thereby improving the electrochemical performance. The preparation method has the advantages of simple process and high repeatability, and is beneficial to the popularization and use of the preparation method.

The invention also discloses a tin element composite tungsten disulfide/reduced graphene oxide composite electrode material prepared by the above preparation method. In this material, simple tin nanoparticles are grown on tungsten disulfide nanosheets by reduction, and the scanning electron microscope test shows that the simple tin nanoparticles can be uniformly dispersed on the surface of the WS ₂ /rGO composite material. Therefore, in this material, it is possible to use The tin element with excellent electrical conductivity improves the overall electrochemical performance of the tin element composite tungsten disulfide/reduced graphene oxide composite electrode material.

Further, through the cycle performance test, it can be known that the tin simple substance composite tungsten disulfide/reduced graphene oxide composite electrode material obtained by the present invention has a capacity retention rate of 92 after being cycled for 200 cycles at a current density of 200mA g ^-1 . %, so it has excellent cycle stability.

The invention also discloses the application of the above-mentioned tin element composite tungsten disulfide/reduced graphene oxide composite electrode material as a battery negative electrode material. The Sn@WS ₂ /rGO composite electrode material prepared by this method has broad research value and application value in the field of electrochemistry.

Description of drawings

1 is an X-ray diffraction (XRD) pattern of the Sn@WS ₂ /rGO composite electrode material prepared in Example 3 of the present invention;

2 is a scanning electron microscope (SEM) photograph of the Sn@WS ₂ /rGO composite electrode material prepared in Example 3 of the present invention; wherein (a) is a low-magnification image, and (b) is a high-magnification image;

Fig. 3 is a cycle performance diagram of the Sn@WS ₂ /rGO composite electrode material prepared in Example 3 of the present invention;

4 is a graph of the rate performance of the Sn@WS ₂ /rGO composite electrode material prepared in Example 3 of the present invention.

Detailed ways

In order to make those skilled in the art better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only Embodiments are part of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that the terms "first", "second" and the like in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific sequence or sequence. It is to be understood that the data so used may be interchanged under appropriate circumstances such that the embodiments of the invention described herein can be practiced in sequences other than those illustrated or described herein. Furthermore, the terms "comprising" and "having" and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those expressly listed Rather, those steps or units may include other steps or units not expressly listed or inherent to these processes, methods, products or devices.

The specific technical scheme is as follows: a method for preparing a composite product of tin elemental composite tungsten disulfide/reduced graphene oxide (Sn@WS ₂ /rGO), comprising the following steps:

Step 1: At room temperature, add 30-60 mg of rGO to 30-60 mL of deionized water and sonicate for 2-6 h to form a homogeneous solution A, and control its concentration to be 0.5-2 mol/L. Ultrasonic power is 300-1000W;

Step 2: Take 0.295-0.59 g of tungsten hexachloride and 0.5625-1.125 g of thioacetamide into solution A, stir at a speed of 500-800 r/min, and stir for 0.5-3 h, the obtained solution is solution B.

Step 3: transfer the above solution C to the hydrothermal kettle, control the filling ratio at 30% to 60%, then seal the hydrothermal kettle, and in the homogeneous reaction apparatus, control the hydrothermal temperature to be 200 to 240 ° C, and the reaction time to be 12 ~48h, after the reaction was completed, it was naturally cooled to room temperature.

Step 4: Open the reaction kettle, take out the product and wash it with absolute ethanol and deionized water and centrifuge in turn, repeat the washing for 4 to 6 times and then place it in a freeze dryer with a temperature of -40 to -70°C and a vacuum of 10 to 40Pa. After drying for 8-12 hours, a black WS ₂ /rGO composite material was obtained.

Step 5: Dissolve PVP and stannous chloride dihydrate completely in 10-30 mL aqueous solution, stir for 10-60 min, and the stirring speed is 500-800 r/min. The above-mentioned WS ₂ /rGO composite material is added, and the mixture is stirred for 0.5 to 2 hours, and the stirring speed is 500 to 800 r/min. After mixing evenly, add sodium borohydride to control m(PVP):m(stannous chloride dihydrate):m(WS ₂ /rGO):(sodium borohydride)=(1～4):(1～4): (1 to 4): (0.2 to 1). Stir for 0.5 to 1 h, and the stirring speed is 500 to 800 r/min.

Step 6: Wash the above-mentioned precursor solution with absolute ethanol and deionized water and centrifuge, repeat the washing for 4 to 6 times, and then place it in a freeze dryer with a temperature of -40 to -70°C and a vacuum of 10 to 40 Pa to dry for 8 ~12h, a black Sn@WS ₂ /rGO composite was obtained.

Step 7: Take the above-mentioned Sn@WS ₂ /rGO composite material for annealing treatment in a low temperature tube furnace, calcined at 400-600°C under the protection of argon atmosphere, the heating rate is 5-20°C/min, and the temperature is kept for 1-3h , the obtained product is Sn@WS ₂ /rGO composite electrode material.

Below in conjunction with specific embodiment, the present invention is described in further detail:

Example 1

Step 1: At room temperature, add 30 mg of rGO to 60 mL of deionized water for 2 h to form a homogeneous solution A, and control its concentration to 0.5 mol/L. Ultrasonic power is 1000W;

Step 2: Take 0.295g of tungsten hexachloride and 0.5625g of thioacetamide into solution A, stir at a speed of 800r/min, stir for 3h, and the obtained solution is solution B.

Step 3: Transfer the above solution C to the hydrothermal kettle, control the filling ratio at 60%, then seal the hydrothermal kettle, and in the homogeneous reaction apparatus, control the hydrothermal temperature to be 240°C, and the reaction time to be 12h. Cool to room temperature.

Step 4: Open the reaction kettle, take out the product, wash it with absolute ethanol and deionized water in turn and centrifuge, repeat the washing for 6 times and place it in a freeze dryer with a temperature of -70°C and a vacuum of 40Pa for 8h to obtain a black color. WS ₂ /rGO composites.

Step 5: Dissolve PVP and stannous chloride dihydrate completely in 15 mL of aqueous solution, stir for 20 min, and the stirring speed is 800 r/min. The above WS ₂ /rGO composite material was added and stirred for 0.5 h at a stirring speed of 800 r/min. After mixing evenly, sodium borohydride was added to control m(PVP):m(stannous chloride dihydrate):m(WS ₂ /rGO):(sodium borohydride)=4:4:4:1. Stir for 1 h at a stirring speed of 800 r/min.

Step 6: Wash the above precursor solution with absolute ethanol and deionized water and centrifuge, repeat the washing for 4 times, and then place it in a freeze dryer with a temperature of -40°C and a vacuum of 10Pa for 8h to obtain black Sn@ WS ₂ /rGO composites.

Step 7: Take the above Sn@WS ₂ /rGO composite material for annealing treatment in a low temperature tube furnace, under the protection of argon atmosphere, calcined at 600 °C, the heating rate is 20 °C/min, and the temperature is kept for 1 h, the obtained product is Sn@ WS ₂ /rGO composite electrode material.

Example 2

Step 1: At room temperature, add 50 mg of rGO to 60 mL of deionized water for 5 h to form a homogeneous solution A, and control its concentration to 1.2 g/L. Ultrasonic power is 800W;

Step 2: Take 0.59g of tungsten hexachloride and 1.125g of thioacetamide into solution A, stir at a speed of 600r/min, and stir for 3h, and the obtained solution is solution B.

Step 3: Transfer the above solution C to a hydrothermal kettle, control the filling ratio at 60%, then seal the hydrothermal kettle, and in a homogeneous reaction apparatus, control the hydrothermal temperature to be 240°C, and the reaction time to be 48h. Cool to room temperature.

Step 4: Open the reaction kettle, take out the product, wash it with absolute ethanol and deionized water in turn and centrifuge, repeat the washing for 6 times and then place it in a freeze dryer with a temperature of -70°C and a vacuum of 10Pa for 10h to obtain a black color. WS ₂ /rGO composites.

Step 5: Dissolve PVP and stannous chloride dihydrate completely in 25 mL of aqueous solution, stir for 60 min, and the stirring speed is 500 r/min. The above-mentioned WS ₂ /rGO composite material was added and stirred for 0.5 h at a stirring speed of 500 r/min. After mixing uniformly, add sodium borohydride to control m(PVP):m(stannous chloride dihydrate):m(WS ₂ /rGO):(sodium borohydride)=3:2:1:0.5. Stir for 1 h at a stirring speed of 800 r/min.

Step 6: Wash the above precursor solution with absolute ethanol and deionized water and centrifuge, repeat the washing for 5 times, and then place it in a freeze dryer with a temperature of -40°C and a vacuum of 10Pa for 12h to obtain black Sn@ WS ₂ /rGO composites.

Step 7: Take the above Sn@WS ₂ /rGO composite material for annealing treatment in a low temperature tube furnace, under the protection of argon atmosphere, calcined at 500 °C, the heating rate is 10 °C/min, and the temperature is kept for 3 h, the obtained product is Sn@ WS ₂ /rGO composite electrode material.

Example 3

Step 1: At room temperature, add 60 mg of rGO to 60 mL of deionized water for 6 h to form a homogeneous solution A, and control its concentration to 1 mol/L. Ultrasonic power is 500W;

Step 2: Take 0.59g of tungsten hexachloride and 1.125g of thioacetamide into solution A, stir at a speed of 800r/min, and stir for 2h, and the obtained solution is solution B.

Step 3: Transfer the above solution C to the hydrothermal kettle, the filling ratio is controlled at 60%, and then the hydrothermal kettle is sealed, and in the homogeneous reaction apparatus, the hydrothermal temperature is controlled to be 200°C, and the reaction time is 24h. Cool to room temperature.

Step 4: Open the reaction kettle, take out the product, wash it with absolute ethanol and deionized water and centrifuge in turn, repeat the washing for 4 to 6 times, and then place it in a freeze dryer with a temperature of -60 ° C and a vacuum of 25 Pa for 10 hours, A black WS ₂ /rGO composite was obtained.

Step 5: Dissolve PVP and stannous chloride dihydrate completely in 10 mL of aqueous solution, stir for 30 min, and the stirring speed is 800 r/min. The above WS ₂ /rGO composite material was added and stirred for 0.5 h at a stirring speed of 800 r/min. After mixing evenly, sodium borohydride was added to control m(PVP):m(stannous chloride dihydrate):m(WS ₂ /rGO):(sodium borohydride)=4:4:4:1. Stir for 1 h at a stirring speed of 800 r/min.

Step 6: Wash the above precursor solution with absolute ethanol and deionized water and centrifuge, repeat the washing for 6 times and then place it in a freeze dryer with a temperature of -70°C and a vacuum of 40Pa for 12h to obtain black Sn@ WS ₂ /rGO composites.

Step 7: Take the above Sn@WS ₂ /rGO composite material for annealing treatment in a low temperature tube furnace, under the protection of argon atmosphere, calcined at 500 °C, the heating rate is 10 °C/min, and the temperature is kept for 2 h, the obtained product is Sn@ WS ₂ /rGO composite electrode material.

Example 4

Step 1: At room temperature, add 40 mg of rGO to 60 mL of deionized water and sonicate for 2 to 6 h to form a homogeneous solution A, with a concentration of 0.67 g/L. Ultrasonic power is 1000W;

Step 2: Take 0.358g of tungsten hexachloride and 1.08g of thioacetamide into solution A, stir at a speed of 500r/min, and stir for 3h, and the obtained solution is solution B.

Step 3: Transfer the above solution C to the hydrothermal kettle, control the filling ratio at 60%, then seal the hydrothermal kettle, and in the homogeneous reaction apparatus, control the hydrothermal temperature to be 210°C, and the reaction time to be 36h. Cool to room temperature.

Step 4: Open the reaction kettle, take out the product, wash it with absolute ethanol and deionized water in turn and centrifuge, repeat the washing for 6 times, and then place it in a freeze dryer with a temperature of -40 ° C and a vacuum of 10 Pa for 9 hours to dry to obtain a black color. WS ₂ /rGO composites.

Step 5: Dissolve PVP and stannous chloride dihydrate completely in 20 mL of aqueous solution, stir for 25 min, and the stirring speed is 500 r/min. The above-mentioned WS ₂ /rGO composite material was added and stirred for 1 h at a stirring speed of 500 r/min. After mixing uniformly, sodium borohydride was added to control m(PVP):m(stannous chloride dihydrate):m(WS ₂ /rGO):(sodium borohydride)=3:3:1:0.5. Stir for 1 h at a stirring speed of 800 r/min.

Step 6: Wash the above precursor solution with absolute ethanol and deionized water and centrifuge, repeat the washing for 6 times and then place it in a freeze dryer with a temperature of -70°C and a vacuum of 40Pa for 12h to obtain black Sn@ WS ₂ /rGO composites.

Step 7: Take the above-mentioned Sn@WS ₂ /rGO composite material for annealing treatment in a low temperature tube furnace, under the protection of argon atmosphere, calcining at 550 ° C, heating rate of 15 ° C/min, and holding for 3 h, the obtained product is Sn@WS ₂ /rGO composite electrode material.

Example 5

Step 1: At room temperature, add 60 mg of rGO to 30 mL of deionized water and sonicate for 2 to 6 h to form a homogeneous solution A, with a concentration of 2 g/L. Ultrasonic power is 800W;

Step 2: Take 0.298g of tungsten hexachloride and 0.875g of thioacetamide into solution A, stir at a speed of 500r/min, stir for 3h, and the obtained solution is solution B.

Step 3: Transfer the above solution C to the hydrothermal kettle, the filling ratio is controlled at 30%, then seal the hydrothermal kettle, and in the homogeneous reaction apparatus, control the hydrothermal temperature to be 240°C, and the reaction time to be 12h. Cool to room temperature.

Step 4: Open the reaction kettle, take out the product, wash it with absolute ethanol and deionized water and centrifuge in turn, repeat the washing for 4 times and place it in a freeze dryer with a temperature of -40°C and a vacuum of 10Pa for 8h to obtain a black color. WS ₂ /rGO composites.

Step 5: Dissolve PVP and stannous chloride dihydrate completely in 30 mL of aqueous solution, stir for 60 min, and the stirring speed is 800 r/min. The above WS ₂ /rGO composite material was added and stirred for 2 h at a stirring speed of 800 r/min. After mixing uniformly, add sodium borohydride to control m(PVP):m(stannous chloride dihydrate):m(WS ₂ /rGO):(sodium borohydride)=1:2:4:1. Stir for 1 h at a stirring speed of 800 r/min.

Step 6: Wash the above precursor solution with absolute ethanol and deionized water and centrifuge, repeat the washing for 6 times and then place it in a freeze dryer with a temperature of -70°C and a vacuum of 40Pa for 12h to obtain black Sn@ WS ₂ /rGO composites.

Step 7: Take the above Sn@WS ₂ /rGO composite material for annealing treatment in a low temperature tube furnace, under the protection of argon atmosphere, calcined at 400 °C, the heating rate is 5 °C/min, and the temperature is kept for 3 h, the obtained product is Sn@ WS ₂ /rGO composite electrode material.

Example 6

Step 1: At room temperature, add 40 mg of rGO to 40 mL of deionized water and sonicate for 2 to 6 h to form a homogeneous solution A, and control its concentration to 1 g/L. Ultrasonic power is 800W;

Step 2: Take 0.295g of tungsten hexachloride and 0.5625g of thioacetamide into solution A, stir at a speed of 500r/min, stir for 3h, and the obtained solution is solution B.

Step 3: Transfer the above solution C to the hydrothermal kettle, the filling ratio is controlled at 30%, then seal the hydrothermal kettle, and in the homogeneous reaction apparatus, control the hydrothermal temperature to be 200°C, and the reaction time to be 12h. Cool to room temperature.

Step 4: Open the reaction kettle, take out the product, wash it with absolute ethanol and deionized water and centrifuge in turn, repeat the washing for 4 times and place it in a freeze dryer with a temperature of -40°C and a vacuum of 10Pa for 8h to obtain a black color. WS ₂ /rGO composites.

Step 5: Dissolve PVP and stannous chloride dihydrate completely in 30 mL of aqueous solution, stir for 60 min, and the stirring speed is 800 r/min. The above WS ₂ /rGO composite material was added and stirred for 2 h at a stirring speed of 800 r/min. After mixing evenly, sodium borohydride was added to control m(PVP):m(stannous chloride dihydrate):m(WS ₂ /rGO):(sodium borohydride)=1:1:2:0.2. Stir for 1 h at a stirring speed of 800 r/min.

Step 6: Wash the above precursor solution with absolute ethanol and deionized water and centrifuge, repeat the washing for 6 times and then place it in a freeze dryer with a temperature of -70°C and a vacuum of 40Pa for 12h to obtain black Sn@ WS ₂ /rGO composites.

Step 7: Take the above Sn@WS ₂ /rGO composite material for annealing treatment in a low temperature tube furnace, under the protection of argon atmosphere, calcined at 400 °C, the heating rate is 5 °C/min, and the temperature is kept for 2 h, the obtained product is Sn@ WS ₂ /rGO composite electrode material.

In conclusion, the present invention utilizes solvothermal method and normal temperature liquid phase reduction process to prepare Sn@WS ₂ /rGO composite material with the aid of template agent, and grow Sn nanometers on tungsten disulfide nanosheets of WS ₂ /rGO composite material by reduction. The particles can effectively enhance the conductivity of the material, thereby improving the electrochemical performance of the material. The preparation process is simple, the process parameters are easy to control, and the repeatability is high. The Sn@WS ₂ /rGO composite material prepared by this method has broad research value and application value in the field of electrochemistry.

Below in conjunction with accompanying drawing, the present invention is described in further detail:

Referring to FIG. 1 , it is an X-ray diffraction (XRD) pattern of the Sn@WS ₂ /rGO composite electrode material prepared in Example 3. The characteristic peaks of Sn and WS ₂ can be clearly seen without the existence of other impurity phases, indicating that the Sn@WS ₂ /rGO composite electrode material has been successfully prepared by the present invention.

Referring to FIG. 2 , it is a scanning electron microscope (SEM) photograph of the Sn@WS ₂ /rGO composite electrode material prepared in Example 3. It can be seen that the Sn particles are relatively uniformly distributed on the surface of the WS ₂ /rGO composite material, so the tin element with excellent electrical conductivity can be used, and finally the overall electrochemical performance of the tin element composite tungsten disulfide/reduced graphene oxide composite electrode material can be improved. performance.

Referring to FIG. 3 , it is a cycle performance diagram of the Sn@WS ₂ /rGO composite electrode material prepared in Example 3. It can be seen that after 200 cycles at a current density of 200 mA·g ^-1 , the capacity retention rate is 92%, which shows that the cycle stability is good.

Referring to FIG. 4 , which is the rate performance diagram of the Sn@WS ₂ /rGO composite electrode material prepared in Example 3 of the present invention, it can be seen that its capacity can still reach 100mAh·g ^{-1 at a current density of 20A·g -1 .} Therefore, according to Figure 3 and Figure 4, it can be seen that the use of metal element has better conductivity, that is, Sn element as the negative electrode material of sodium ion battery can have a higher theoretical capacity, so on the premise of maintaining high capacity, the use of metal element Sn The composite enhances the conductivity of the material, so that the tin element composite tungsten disulfide/reduced graphene oxide composite electrode material finally prepared by the present invention exhibits excellent cycle stability and rate performance.

Specifically, the above experimental test chart corresponds to: the sample (Sn@WS ₂ /rGO composite electrode material) was analyzed with Rigaku D/max2000PC X-ray diffractometer, and it was found that the sample was similar to the WS ₂ of the hexagonal crystal system with the JCPDS number of 08-0237. The structures are consistent, indicating that this method can produce high-purity tungsten disulfide. The sample was observed with a field emission scanning electron microscope (FESEM), and it can be seen that the prepared Sn@WS ₂ /rGO composite electrode material has good product dispersion.

The above content is only to illustrate the technical idea of the present invention, and cannot limit the protection scope of the present invention. Any modification made on the basis of the technical solution proposed in accordance with the technical idea of the present invention falls within the scope of the claims of the present invention. within the scope of protection.

Claims (9)

1. a preparation method of tin elemental composite tungsten disulfide/reduced graphene oxide composite electrode material, is characterized in that, comprises the following steps: 1) uniformly dispersing reduced graphene oxide, tungsten hexachloride and thioacetamide in water to obtain a reaction solution; cooling the reaction solution after hydrothermal reaction to obtain a product, and after centrifugal washing of the product, the powder is collected by freeze-drying , to obtain tungsten disulfide/reduced graphene oxide composite material; 2) adding polyvinylpyrrolidone, stannous chloride dihydrate, tungsten disulfide/reduced graphene oxide composite material and sodium borohydride to the water and uniformly dispersing to obtain a precursor liquid; after the centrifugal washing of the precursor liquid, the powder is collected by freeze-drying, A tin elemental composite tungsten disulfide/reduced graphene oxide composite material is obtained; 3) calcining and annealing the tin element composite tungsten disulfide/reduced graphene oxide composite material to obtain a tin element compound tungsten disulfide/reduced graphene oxide composite electrode material. 2. the preparation method of tin elemental composite tungsten disulfide/reduced graphene oxide composite electrode material according to claim 1, is characterized in that, in step 1), in reduced graphene oxide, water, tungsten hexachloride and thioethyl The reaction feed ratio of the amide is (30-60) mg: (30-60) mL: (0.295-0.59) g: (0.5625-1.125) g. 3. the preparation method of tin elemental composite tungsten disulfide/reduced graphene oxide composite electrode material according to claim 1, is characterized in that, in step 1), the hydrothermal reaction temperature is 200～240 ℃, and the reaction time is 12～ 48h. 4. the preparation method of tin elemental composite tungsten disulfide/reduced graphene oxide composite electrode material according to claim 1, is characterized in that, in step 2), polyvinylpyrrolidone, stannous chloride dihydrate, tungsten disulfide/ The reaction feed ratio of the reduced graphene oxide composite material, sodium borohydride and water is (1-4) mg: (1-4) mg: (1-4) mg: (0.2-1) mg: (10-30) mL. 5. the preparation method of tin elemental composite tungsten disulfide/reduced graphene oxide composite electrode material according to claim 1, is characterized in that, in step 1) and step 2), the temperature of freeze-drying is-40～-70 ℃ , the time is 8~12h, and the vacuum degree of the freeze-drying environment is 10~40Pa. 6. the preparation method of tin elemental composite tungsten disulfide/reduced graphene oxide composite electrode material according to claim 1, is characterized in that, the calcination annealing treatment in step 3) specifically comprises: under the protection of inert atmosphere, calcination temperature The temperature is 400-600°C, the heating rate is 5-20°C/min, and the temperature is kept for 1-3h. 7. The tin element composite tungsten disulfide/reduced graphene oxide composite electrode material prepared by the preparation method according to any one of claims 1 to 6. 8. tin element compound tungsten disulfide/reduced graphene oxide compound electrode material according to claim 7, is characterized in that, described tin element compound tungsten disulfide/reduced graphene oxide compound electrode material is at 200mA g ^-1 After 200 cycles at the same current density, the capacity retention rate was 92%. 9. The application of the tin element composite tungsten disulfide/reduced graphene oxide composite electrode material as described in claim 7 or 8 as a battery negative electrode material.

Images