A tin-based negative electrode material for lithium-ion batteries with dual confinement effect and a preparation method thereof

Abstract

The present invention discloses a tin-based negative electrode material for lithium-ion batteries with a dual confinement effect and a preparation method thereof. In the composite material, sulfur-nitrogen co-doped graphene is first prepared by electrochemical stripping, and then a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material is obtained by chemical tin plating and carbon coating. In the composite material, the carbon coating and sulfur-nitrogen co-doped graphene network "double confine" the tin, which can stabilize the structure of the tin, prevent the tin from agglomerating during heat treatment and circulation, and improve the electrochemical performance of the tin-based composite material. This method is an effective method for obtaining high-performance tin-based negative electrode materials, and has promoting significance for the development of new negative electrode materials for lithium-ion batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a tin-based negative electrode material for a lithium ion battery with a double confinement effect and a preparation method thereof. Background Art

[0002] Lithium-ion batteries play an important role in fields such as electric vehicles and portable electronic devices due to their advantages of high energy density, environmental friendliness and no memory effect. With the continuous development of technology, the demand for research on high-performance battery negative electrode materials has also increased. Graphite has the characteristics of low cost, good electronic conductivity, long cycle life and stable capacity. It is one of the negative electrode materials currently used in commercial applications of lithium-ion batteries. For the negative electrode materials of lithium-ion batteries, the capacity of commercial graphite-based carbon negative electrode materials is very close to the theoretical specific capacity of graphite (372mAh g -1 ), it is very difficult to improve the specific capacity of such materials. In order to obtain negative electrode materials with higher specific capacity, researchers need to conduct more in-depth research to explore and develop new high-performance negative electrode materials.

[0003] Among the many new potential negative electrode materials, tin-based materials can form alloy compounds with lithium metal with high specific capacity, Li 4.4 Sn. In particular, the theoretical specific capacity of metallic tin is as high as 994 mAh g -1 , which is more than 2 times higher than the specific capacity of commercial graphite carbon materials. In addition, metallic tin has attracted attention due to its advantages such as abundant reserves, high safety and environmental friendliness, making it considered a good material to replace commercial graphite carbon negative electrodes in lithium-ion batteries. However, metallic tin is prone to huge volume expansion and contraction during the insertion and extraction of lithium ions, causing the metallic tin to become powdery and fall off from the current collector, ultimately leading to a serious reduction in the specific capacity of the electrode material, and deterioration of the cycle performance and rate performance. In order to alleviate this problem, many researchers have conducted research on metallic tin nano-sizing, the introduction of active or inactive buffer matrices, etc. Among them, the introduction of a matrix with a buffering effect, such as carbon material, can effectively reduce the impact of the "volume effect" of metallic tin on the reduction of electrode capacity and the deterioration of cycle life.

[0004] Graphene is a two-dimensional carbon nanomaterial with a large specific surface area, good mechanical elasticity, and superior electrical conductivity. By combining metallic tin with graphene, the large specific surface area and high electrical conductivity of graphene can not only provide sufficient space to alleviate the volume expansion and contraction effects of metallic tin, but also improve the cyclic stability of the composite material and reduce the internal resistance of the composite material. Studies have shown that graphene doped with heteroatoms such as B, N, S, and P can improve the electronic properties of the composite material, increase the lithium storage capacity of the material, and reduce the internal resistance of the material. Although tin / graphene materials can be prepared by various means, such materials still face great challenges in terms of low-cost and large-scale preparation. Therefore, the exploration and development of tin / graphene composite materials that are simple, fast, highly controllable, and easy to prepare on a large scale has become a research hotspot. Summary of the Invention

[0005] The present invention aims to address these issues by utilizing carbon-coated and sulfur-nitrogen co-doped graphene networks to achieve "double confinement" of tin. This method stabilizes the tin structure, prevents tin aggregation during heat treatment and cycling, and improves the electrochemical performance of tin-based composite materials. This method is an effective way to obtain high-performance tin-based negative electrode materials and has significant implications for the development of new negative electrode materials for lithium-ion batteries.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a tin-based negative electrode material for a lithium-ion battery with a dual confinement effect comprises the following steps:

[0008] 1) Weigh a certain amount of sodium sulfate, ammonium sulfate, or a mixture of sodium sulfate and ammonium sulfate, add a certain amount of distilled water, and stir the mixture by ultrasonication, magnetic stirring, or mechanical stirring at room temperature for a certain period of time;

[0009] 2) Weigh a certain amount of thiourea, cysteine, or glycine and dissolve it in the above solution. Stir magnetically, mechanically, or ultrasonically for a certain period of time at room temperature.

[0010] 3) A platinum electrode and graphite foil are formed into a two-electrode system, and electrochemical exfoliation is performed under certain voltage and time conditions to prepare sulfur-nitrogen co-doped graphene;

[0011] 4) The exfoliated sulfur-nitrogen co-doped graphene is filtered and washed multiple times with ethanol, distilled water, or a mixture of distilled water and ethanol, or is centrifuged to clean it;

[0012] 5) adding a certain mass of Triton X-100 to the prepared sulfur-nitrogen co-doped graphene solution, and then performing a chemical tin plating reaction in a tin plating solution of a certain concentration and temperature for a certain time;

[0013] 6) After the chemical tin plating reaction is completed, filter and wash with ethanol, distilled water or a mixture of distilled water and ethanol several times or centrifuge to clean it, and dry it;

[0014] 7) dissolving the obtained tin / sulfur-nitrogen co-doped graphene material in a certain volume of distilled water, weighing a certain mass of glucose, citric acid, sucrose, or dopamine, or a mixture of the two, and dissolving them in the above solution, and then evaporating the distilled water;

[0015] 8) calcining the dried solid in an atmosphere of nitrogen, argon, or a mixture of nitrogen and argon at a certain flow rate and temperature for a certain time, and then cooling it to room temperature by programmed cooling to obtain a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material.

[0016] In the present invention, it is further described that in step 1), the mass of sodium sulfate, ammonium sulfate or a mixture of sodium sulfate and ammonium sulfate is weighed to be 6.6 to 66 g, the amount of distilled water is 500 to 1000 mL, and the ultrasonic, magnetic stirring or mechanical stirring time is 30 to 120 min at room temperature.

[0017] In the present invention, it is further described that in step 2), the mass of thiourea, cysteine or glycine is weighed to be 7.5 to 60.6 g, and the time of magnetic stirring, mechanical stirring or ultrasonication is 30 to 120 min under room temperature.

[0018] In the present invention, it is further described that in step 3), a platinum sheet electrode and a graphite foil are formed into a two-electrode system, and electrochemical stripping is performed at a voltage of 5 to 15 V for 6 to 12 hours to prepare sulfur-nitrogen co-doped graphene.

[0019] In the present invention, it is further described that in step 5), the mass of Triton X-100 is added in an amount of 0.05 to 1 g, and the prepared sulfur-nitrogen co-doped graphene is plated at a tin concentration of 2 to 20 g L -1 The chemical tin plating is carried out in a solution of 10 to 240 minutes, and the tin plating temperature is 55 to 95°C.

[0020] In the present invention, it is further described that in step 7), 0.1 to 5 g of glucose, citric acid, sucrose or dopamine or a mixture of the two is weighed and dissolved in the solution, and then the distilled water is evaporated to dryness.

[0021] In the present invention, it is further described that in step 8), the dried solid is calcined in an atmosphere of nitrogen, argon or a mixture of nitrogen and argon, the calcination temperature is 400-600°C, the holding time is 0.5-3h, and the gas flow rate is 50-200mL / min. Then, the temperature is cooled to room temperature by programmed cooling, thereby obtaining a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material.

[0022] The present invention also provides a lithium ion battery tin-based negative electrode material with a dual confinement effect, which is specifically prepared by the above-mentioned preparation method of the lithium ion battery tin-based negative electrode material with a dual confinement effect.

[0023] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0024] This invention utilizes electrochemical exfoliation to prepare sulfur-nitrogen co-doped graphene, followed by electroless tin plating and carbon coating to produce a carbon-coated tin / sulfur-nitrogen co-doped graphene composite. In this composite, the carbon coating and sulfur-nitrogen co-doped graphene network provide "double confinement" for tin, stabilizing its structure and preventing tin aggregation during heat treatment and cycling, thereby improving the electrochemical performance of the tin-based composite. This method is an effective way to obtain high-performance tin-based anode materials and has significant implications for the development of new anode materials for lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Figure A is a SEM image of sulfur-nitrogen co-doped graphene and carbon-coated tin / sulfur-nitrogen co-doped graphene composite materials. Figure B is a SEM image of sulfur-nitrogen co-doped graphene of the present invention; Figure B is a SEM image of a tin-plated graphene with a concentration of 5 g L -1 SEM image of carbon-coated tin / sulfur-nitrogen co-doped graphene composite material; Figure C is a graphene composite material with a tin plating concentration of 7.5 g L -1 SEM images of carbon-coated tin / sulfur-nitrogen co-doped graphene composites; Figure D shows the SEM images of carbon-coated tin / sulfur-nitrogen co-doped graphene composites with a tin plating concentration of 10 g L -1 SEM image of carbon-coated tin / sulfur-nitrogen co-doped graphene composite material.

[0026] Figure 2 Figure 1 shows the structural characterization of carbon-coated tin / sulfur-nitrogen co-doped graphene composite materials. Figure A shows the XRD patterns of carbon-coated tin / sulfur-nitrogen co-doped graphene composite materials prepared at different tin plating concentrations according to the present invention; Figure B shows the Raman patterns of carbon-coated tin / sulfur-nitrogen co-doped graphene composite materials prepared at different tin plating concentrations; Figure C shows the nitrogen adsorption-desorption isotherms of carbon-coated tin / sulfur-nitrogen co-doped graphene composite materials prepared at different tin plating concentrations; and Figure D shows the pore size distribution of carbon-coated tin / sulfur-nitrogen co-doped graphene composite materials prepared at different tin plating concentrations.

[0027] Figure 3 Figure 1 is the electrochemical performance diagram of the carbon-coated tin / sulfur-nitrogen co-doped graphene composite material of the present invention. Figure A is the electrochemical performance diagram of the carbon-coated tin / sulfur-nitrogen co-doped graphene composite material of the present invention. -1 Cyclic voltammogram of carbon-coated tin / sulfur-nitrogen co-doped graphene composite material; Figure B shows the cyclic voltammogram of carbon-coated tin / sulfur-nitrogen co-doped graphene composite material with a tin plating concentration of 5 g L -1The charge and discharge curves of carbon-coated tin / sulfur-nitrogen co-doped graphene composites; Figure C shows the charge and discharge curves of carbon-coated tin / sulfur-nitrogen co-doped graphene composites with a tin plating concentration of 7.5 g L -1 The charge and discharge curves of carbon-coated tin / sulfur-nitrogen co-doped graphene composites; Figure D shows the charge and discharge curves of carbon-coated tin / sulfur-nitrogen co-doped graphene composites with a tin plating concentration of 10 g L -1 Charge and discharge curves of carbon-coated tin / sulfur-nitrogen co-doped graphene composites.

[0028] Figure 4 Figure 1 is an electrochemical performance diagram of the carbon-coated tin / sulfur-nitrogen co-doped graphene composite material of the present invention. Figure A is a cycling performance diagram of the carbon-coated tin / sulfur-nitrogen co-doped graphene composite material prepared at different tin plating concentrations; Figure B is a rate performance diagram of the carbon-coated tin / sulfur-nitrogen co-doped graphene composite material prepared at different tin plating concentrations; Figure C is an AC impedance diagram of the carbon-coated tin / sulfur-nitrogen co-doped graphene composite material prepared at different tin plating concentrations; Figure D is a ω of the carbon-coated tin / sulfur-nitrogen co-doped graphene composite material prepared at different tin plating concentrations. -1 / 2 Linear relationship graph with Z'.

[0029] Remark: Figure 1-4 C@Sn / SNGr is a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material. DETAILED DESCRIPTION

[0030] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0031] Example 1:

[0032] Weigh 13.21g of ammonium sulfate and dissolve it in 1000mL of distilled water. Ultrasonicate at room temperature for 30 minutes. Then add 7.51g of glycine to the solution and ultrasonically disperse it for 30 minutes. Place a platinum electrode and graphite foil in the above solution to form a two-electrode system. Set the power supply voltage to 12V and perform electrochemical stripping for 6 hours. Then, centrifuge and clean the sulfur-nitrogen co-doped graphene in distilled water. The concentration is 5g L -1A tin plating solution was added, followed by the addition of 0.5g of sulfur-nitrogen co-doped graphene and 0.05g of Triton X-100, and chemical tin plating was performed at 80°C for 60 minutes. After the reaction was completed, the resulting tin / sulfur-nitrogen co-doped graphene material was filtered and cleaned under distilled water. 0.3g of the tin / sulfur-nitrogen co-doped graphene material was weighed and dissolved in 20mL of distilled water. 0.1g of glucose was added, and the mixture was heated and stirred until the distilled water evaporated completely. The solid was then calcined at 500°C in a nitrogen-filled tubular furnace for 120 minutes at a constant gas flow rate of 100mL / min. The mixture was then cooled to room temperature to obtain a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material.

[0033] Example 2:

[0034] Weigh 13.21g of ammonium sulfate and dissolve it in 1000mL of distilled water. Ultrasonicate at room temperature for 30 minutes. Then add 7.51g of glycine to the solution and ultrasonically disperse it for 30 minutes. Place a platinum electrode and graphite foil in the above solution to form a two-electrode system. Set the power supply voltage to 12V and perform electrochemical stripping for 6 hours. Then, centrifuge and clean the sulfur-nitrogen co-doped graphene in distilled water. The concentration is 7.5g L -1 A tin plating solution was added, followed by the addition of 0.5g of sulfur-nitrogen co-doped graphene and 0.05g of Triton X-100, and chemical tin plating was performed at 80°C for 60 minutes. After the reaction was completed, the resulting tin / sulfur-nitrogen co-doped graphene material was filtered and cleaned under distilled water. 0.3g of the tin / sulfur-nitrogen co-doped graphene material was weighed and dissolved in 20mL of distilled water. 0.1g of glucose was added, and the mixture was heated and stirred until the distilled water evaporated completely. The solid was then calcined at 500°C in a nitrogen-filled tubular furnace for 120 minutes at a constant gas flow rate of 100mL / min. The mixture was then cooled to room temperature to obtain a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material.

[0035] Example 3:

[0036] Weigh 13.21g of ammonium sulfate and dissolve it in 1000mL of distilled water. Ultrasonicate at room temperature for 30min, then add 7.51g of glycine to the solution and ultrasonically disperse it for 30min. Place a platinum electrode and graphite foil in the above solution to form a two-electrode system. Set the power supply voltage to 12V and perform electrochemical stripping for 6h. Then, centrifuge and clean the sulfur-nitrogen co-doped graphene in distilled water. The concentration is 10g L -1A tin plating solution was added, followed by the addition of 0.5g of sulfur-nitrogen co-doped graphene and 0.05g of Triton X-100, and chemical tin plating was performed at 80°C for 60 minutes. After the reaction was completed, the resulting tin / sulfur-nitrogen co-doped graphene material was filtered and cleaned under distilled water. 0.3g of the tin / sulfur-nitrogen co-doped graphene material was weighed and dissolved in 20mL of distilled water. 0.1g of glucose was added, and the mixture was heated and stirred until the distilled water evaporated completely. The solid was then calcined at 500°C in a nitrogen-filled tubular furnace for 120 minutes at a constant gas flow rate of 100mL / min. The mixture was then cooled to room temperature to obtain a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material.

[0037] Example 4:

[0038] Weigh 13.21g of ammonium sulfate and dissolve it in 1000mL of distilled water. Stir mechanically at room temperature for 50min, then add 7.61g of thiourea to the solution and sonicate for 120min. Place a platinum electrode and graphite foil in the above solution to form a two-electrode system. Set the power supply voltage to 10V and perform electrochemical stripping for 12h. Then, clean the sulfur-nitrogen co-doped graphene by centrifugation in distilled water. The concentration is 10g L -1 A tin plating solution was added, followed by the addition of 0.5g of sulfur-nitrogen co-doped graphene and 0.1g of Triton X-100. Electroless tin plating was performed at 55°C for 30 minutes. After the reaction was complete, the resulting tin / sulfur-nitrogen co-doped graphene material was filtered and cleaned under distilled water. 0.3g of the tin / sulfur-nitrogen co-doped graphene material was weighed and dissolved in 20mL of distilled water. 0.5g of dopamine was added, and the mixture was heated and stirred until the distilled water evaporated completely. The solid was then calcined at 450°C in a tube furnace filled with argon for 0.5h at a constant gas flow rate of 150mL / min. The mixture was then cooled to room temperature to obtain a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material.

[0039] Example 5:

[0040] Weigh 39.63g of ammonium sulfate and dissolve it in 1000mL of distilled water. Ultrasonic dispersion was performed at room temperature for 30min. Then 15.22g of thiourea was added to the solution and mechanically stirred for 120min. A platinum electrode and graphite foil were placed in the above solution to form a two-electrode system. The power supply voltage was set to 10V and electrochemical stripping was performed for 9h. Then, the sulfur-nitrogen co-doped graphene was centrifuged and cleaned in ethanol solution several times. The concentration was 2g L -1A tin plating solution was added, followed by the addition of 0.5g of graphene and 0.1g of Triton X-100, and chemical tin plating was performed at 55°C for 10 minutes. After the reaction was completed, the resulting tin / sulfur-nitrogen co-doped graphene material was filtered and cleaned several times in an ethanol solution. 0.3g of tin / sulfur-nitrogen co-doped graphene material was weighed and dissolved in 20mL of distilled water. 1g of citric acid was added, and the mixture was heated and stirred until the distilled water evaporated completely. The solid was then calcined at 400°C in a tube furnace filled with argon for 0.5h at a constant gas flow rate of 50mL / min, and then cooled to room temperature to obtain a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material.

[0041] Example 6:

[0042] Weigh 14.20g of sodium sulfate and 13.21g of ammonium sulfate and dissolve them in 1000mL of distilled water. Stir magnetically at room temperature for 120min, then add 12.10g of cysteine to the solution and stir mechanically for 100min. Place a platinum electrode and graphite foil in the above solution to form a two-electrode system. Set the power supply voltage to 10V and perform electrochemical stripping for 8h. Then, centrifuge the sulfur-nitrogen co-doped graphene several times in distilled water to clean it. The concentration is 5g L -1 A tin plating solution was prepared, followed by the addition of 0.5 g of sulfur-nitrogen co-doped graphene and 0.2 g of Triton X-100, and chemical tin plating was performed at 95°C for 100 minutes. After the reaction was completed, the resulting tin / sulfur-nitrogen co-doped graphene material was filtered and cleaned with a mixture of distilled water and ethanol. 0.3 g of tin / sulfur-nitrogen co-doped graphene material was weighed and dissolved in 20 mL of distilled water, followed by the addition of 1 g of sucrose. The mixture was heated and stirred until the distilled water evaporated completely. The solid was then calcined at 500°C in a tube furnace filled with a mixture of nitrogen and argon for 1 hour at a constant gas flow rate of 150 mL / min, and then cooled to room temperature to obtain a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material.

[0043] Example 7:

[0044] Weigh 28.4g of sodium sulfate and 13.21g of ammonium sulfate and dissolve them in 1000mL of distilled water. Stir ultrasonically at room temperature for 60min, then add 22.53g of glycine to the solution and stir magnetically for 80min. Place a platinum electrode and graphite foil in the above solution to form a two-electrode system. Set the power supply voltage to 15V and perform electrochemical stripping for 10h. Then, centrifuge the sulfur-nitrogen co-doped graphene in ethanol solution several times to clean it. The concentration is 10g L -1A tin plating solution was added, followed by the addition of 0.5g of sulfur-nitrogen co-doped graphene and 0.1g of Triton X-100, and chemical tin plating was performed at 65°C for 50 minutes. After the reaction was completed, the resulting tin / sulfur-nitrogen co-doped graphene material was filtered and cleaned with distilled water. 0.3g of the tin / sulfur-nitrogen co-doped graphene material was weighed and dissolved in 20mL of distilled water. A mixture of 0.5g of glucose and 0.5g of citric acid was added, and the mixture was heated and stirred until the distilled water evaporated completely. The solid was then calcined at 550°C in a tube furnace filled with a mixture of nitrogen and argon for 1 hour at a constant gas flow rate of 120mL / min, and then cooled to room temperature to obtain a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material.

[0045] Example 8:

[0046] Weigh 26.42g of ammonium sulfate and dissolve it in 1000mL of distilled water. Stir magnetically at room temperature for 70min. Then add 24.20g of cysteine to the solution and stir magnetically for 70min. Place a platinum electrode and graphite foil in the above solution to form a two-electrode system. Set the power supply voltage to 11V and perform electrochemical stripping for 8h. Then, clean the sulfur-nitrogen co-doped graphene by centrifugation with distilled water several times. The concentration is 8g L -1 A tin plating solution was added, followed by the addition of 0.5g of sulfur-nitrogen co-doped graphene and 0.2g of Triton X-100, and chemical tin plating was performed at 75°C for 240 minutes. After the reaction was completed, the resulting tin / sulfur-nitrogen co-doped graphene material was filtered and cleaned multiple times with distilled water. 0.3g of tin / sulfur-nitrogen co-doped graphene material was weighed and dissolved in 20mL of distilled water. 1g of sucrose and 1g of dopamine were added, and the mixture was heated and stirred until the distilled water evaporated completely. The solid was then calcined at 500°C in a tube furnace filled with argon for 1.5 hours at a constant gas flow rate of 180mL / min, and then cooled to room temperature to obtain a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material.

[0047] In the experiment, the applicant conducted research: Figure 1 Shown: From Figure 1 From the structural characterization, it can be concluded that the obtained composite materials all maintain the layered structure of sulfur-nitrogen co-doped graphene, and there are evenly distributed particles on the surface of the material. Figure 2 The results show that the prepared composite material has a mesoporous structure, which is beneficial to increase the lithium storage capacity of the material and promote the diffusion of lithium ions.

[0048] The specific surface area and pore size ratio of the samples obtained in Examples 1-3 are shown in Table 1.

[0049] Table 1

[0050] Sample name <![CDATA[Specific surface area (m 2 g -1 )]]> Pore diameter (nm) C@Sn / SNGr-5 50.6 4.61 C@Sn / SNGr-7.5 100.81 4.46 C@Sn / SNGr-10 96.677 4.57

[0051] from Figure 3 It can be seen that the carbon-coated tin / sulfur-nitrogen co-doped graphene composites have high charge and discharge specific capacity.

[0052] The specific discharge capacity (mAh g) of the sample charge-discharge curves obtained in Examples 1-3 after 1, 2, 5, 100, and 150 cycles -1 ) and Coulombic efficiency (%) are shown in the table below.

[0053] Table 2

[0054]

[0055] from Figure 4 It can be seen that the carbon-coated tin / sulfur-nitrogen co-doped graphene composite material exhibits good cycle performance, rate performance and good conductivity.

[0056] The specific rate performance (mAh g) of the samples obtained in Examples 1-3 -1 ) and impedance values are shown in the table below.

[0057] Table 3

[0058]

[0059] Table 4 Z(Ω) and Z′ and ω -1 / 2 The linear relationship of (σ)

[0060] Sample name Impedance (Ω) <![CDATA[Z′-ω -1 / 2 (s)]]> C@Sn / SNGr-5 474 1341.54 C@Sn / SNGr-7.5 355 231.49 C@Sn / SNGr-10 368 527.01

[0061] The results showed that the tin plating concentration was 7.5 g L -1 The prepared carbon-coated tin / sulfur-nitrogen co-doped graphene composite material has a low impedance value and exhibits good conductivity.

[0062] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that variations and modifications are possible within the scope of the present invention, as would be apparent to those skilled in the art. These variations and modifications fall within the scope of the present invention. Therefore, the scope of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a tin-based negative electrode material for a lithium-ion battery with a dual confinement effect, characterized in that: The following steps are involved: 1) Weigh a certain amount of sodium sulfate, ammonium sulfate, or a mixture of sodium sulfate and ammonium sulfate, add a certain volume of distilled water, and stir the mixture by ultrasonication, magnetic stirring, or mechanical stirring at room temperature for a certain period of time to obtain solution A; 2) Weigh a certain amount of thiourea, cysteine, or glycine and dissolve it in the above solution A. Stir magnetically, mechanically, or ultrasonically at room temperature for a certain period of time to obtain solution B. 3) Platinum electrode and graphite foil were placed in the above solution B to form a two-electrode system, and electrochemical exfoliation was performed under certain voltage and time conditions to prepare sulfur-nitrogen co-doped graphene; 4) The exfoliated sulfur-nitrogen co-doped graphene is filtered and washed multiple times with ethanol, distilled water, or a mixture of distilled water and ethanol, or centrifuged to clean it; 5) adding a certain amount of Triton X-100 to the prepared sulfur-nitrogen co-doped graphene solution, and then performing a chemical tin plating reaction in a tin plating solution of a certain concentration and temperature for a certain time; 6) After the chemical tin plating reaction is completed, filter and wash with ethanol, distilled water or a mixture of distilled water and ethanol several times or centrifuge to clean it, and then dry it; 7) dissolving the obtained tin / sulfur-nitrogen co-doped graphene material in a certain volume of distilled water to obtain solution C, weighing a certain amount of glucose, citric acid, sucrose, or dopamine, or a mixture of the two, and dissolving them in the above solution C, and then evaporating the distilled water to dryness; 8) calcining the dried solid in an atmosphere of nitrogen, argon, or a mixture of nitrogen and argon at a certain flow rate and temperature for a certain period of time, and then cooling the solid to room temperature by programmed cooling, thereby obtaining a tin-based negative electrode material for lithium-ion batteries with a dual confinement effect, namely, a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material.

2. The preparation method according to claim 1, wherein: In step 1), weigh 6.6-66 g of sodium sulfate, ammonium sulfate, or a mixture of sodium sulfate and ammonium sulfate, use 500-1000 mL of distilled water, and ultrasonically, magnetically, or mechanically stir for 30-120 min at room temperature.

3. The preparation method according to claim 1, wherein: In step 2), 7.5 to 60.6 g of thiourea, cysteine, or glycine are weighed, and the magnetic stirring, mechanical stirring, or ultrasonic stirring time is 30 to 120 min at room temperature.

4. The preparation method according to claim 1, wherein: In step 3), a platinum sheet electrode and a graphite foil are formed into a two-electrode system, and electrochemical stripping is performed at a voltage of 5 to 15 V for 6 to 12 hours to prepare sulfur-nitrogen co-doped graphene.

5. The preparation method according to claim 1, wherein: In step 5), 0.05-1 g of Triton X-100 is added, and the prepared sulfur-nitrogen co-doped graphene is plated with a tin concentration of 2-20 g L -1 The chemical tin plating is carried out in a solution of 10~240min, and the tin plating temperature is 55~95℃.

6. The preparation method according to claim 1, wherein: In step 7), 0.1-5 g of glucose, citric acid, sucrose or dopamine or a mixture of the two is weighed and dissolved in the solution, and then the distilled water is evaporated to dryness.

7. The preparation method according to claim 1, wherein: In step 8), the dried solid is calcined in an atmosphere of nitrogen, argon, or a mixture of nitrogen and argon at a calcination temperature of 400-600°C, a holding time of 0.5-3 hours, and a gas flow rate of 50-200 mL / min; the solid is then cooled to room temperature by programmed cooling, thereby obtaining a tin-based negative electrode material for a lithium-ion battery with a dual confinement effect, namely, a carbon-coated tin / sulfur-nitrogen co-doped graphene composite material.

8. A tin-based negative electrode material for lithium-ion batteries with a dual confinement effect, characterized in that: The material is prepared by the method for preparing the lithium-ion battery tin-based negative electrode material with a dual confinement effect according to any one of claims 1 to 7.

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