SnSe2-NiSe2 / CNT sodium ion battery negative electrode material and preparation method thereof

Abstract

The application belongs to the technical field of preparation of sodium ion battery electrode materials, and particularly relates to a SnSe2-NiSe2 / CNT sodium ion battery negative electrode material and a preparation method thereof. The composite material is formed by a negative electrode material tin source and a nickel source, and is loaded on a hollow carbon nanotube (CNT). The composite structure of SnSe2-NiSe2 / CNT in the application is beneficial to the embedding and discharging of sodium ions, enhances the electron and ion transmission, and has good electrochemical performance. The negative electrode composite material has a three-dimensional structure, retains the original morphology of the carbon tube, and is doped with SnSe2-NiSe2 on the basis of the carbon tube, and the hollow structure of the carbon material can have a certain buffering effect on the volume change in the charging and discharging process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of preparation of sodium ion battery electrode materials, and particularly relates to a SnSe2-NiSe2 / CNT sodium ion battery negative electrode material and a preparation method thereof. BACKGROUND

[0002] It is well known that lithium ion batteries, as a kind of commercialized electrochemical energy storage devices, have shown brilliant achievements in the past few decades due to their outstanding advantages such as high reversible capacity, high cycle life and high stability. However, the development of lithium ion batteries is limited due to the problems of scarce reserves (0.0017 wt%), high cost and safety. Therefore, it is imperative to develop a new generation of energy storage devices.

[0003] In recent years, sodium ion batteries have become a research hotspot due to their abundant natural resources (2.3 wt%) and low cost, and they have similar energy storage mechanisms as lithium ion batteries. However, there are still some obstacles in the practical application of sodium ion batteries. These include poor electrical conductivity, low ion diffusion rate, and significant volume expansion during metal ion storage. These factors limit the battery performance of sodium ion batteries and result in poor electrochemical performance.

[0004] In order to break the above bottleneck, people have taken a lot of improvement strategies. For example, changing the morphology to shorten the ion diffusion channel, promoting charge transfer, and reducing volume expansion; and compounding with other materials. However, these improvement methods used in the prior art are not effective, and the electrochemical performance of sodium ion batteries has not been effectively improved. SUMMARY

[0005] To solve the above problems existing in the prior art, the application provides a SnSe2-NiSe2 / CNT sodium ion battery negative electrode material. The application is based on further research and innovation of carrier materials to prepare a special structure of hollow carbon nanotube composite metal material as a sodium ion battery electrode material, which effectively enhances the electrical conductivity of the electrode material, shortens the ion transmission path, accelerates the electron transmission, and makes it have excellent cycle stability.

[0006] To achieve the above purpose, the application adopts the following technical scheme:

[0007] The application discloses a SnSe2-NiSe2 / CNT sodium ion battery negative electrode material, which has a special structure of hollow carbon nanotube composite metal material. The negative electrode composite material is formed by a tin source and a nickel source to form a composite material SnSe2-NiSe2, and the composite material SnSe2-NiSe2 is uniformly loaded on the hollow carbon nanotube.

[0008] The application utilizes a hydrothermal method to prepare SnSe2-NiSe2 / CNT sodium ion battery negative electrode material, the preparation method is simple, has low cost, the prepared material has high yield, and has good electrochemical cycle performance.

[0009] The application provides a preparation method of SnSe2-NiSe2 / CNT sodium ion battery negative electrode material prepared by a hydrothermal method, and specifically comprises the following steps:

[0010] (1) nickel source and sodium citrate are sequentially dissolved in deionized water, SnCl4·5H2O ethanol solution is added dropwise into the above solution under vigorous stirring to dissolve; NaOH solution and PPy (poly-pyrrole) are continuously added, and the mixed solution is transferred into a high-pressure kettle for heating treatment.

[0011] (2) the precursor obtained in step (1) is placed in a tube furnace and calcined under inert gas to obtain SnO2-NiO2 / CNT;

[0012] (3) SnO2-NiO2 / CNT obtained in step (2) is mixed with selenium powder and uniformly ground, and is annealed under an inert atmosphere to prepare SnSe2-NiSe2 / CNT composite sodium ion battery positive electrode material, wherein SnSe2-NiSe2 is uniformly loaded on CNT.

[0013] Preferably, the nickel source in step (1) is at least one of nickel chloride hexahydrate and nickel nitrate hexahydrate.

[0014] Preferably, the molar ratio of the nickel source to sodium citrate is 1:1, the molar ratio of the nickel source to SnCl4·5H2O is 1:(1-2), and the mass ratio of the nickel source to PPy is (4-5):3; the concentration of the NaOH solution is 2 moL / L.

[0015] Further preferably, the molar ratio of the nickel source to SnCl4·5H2O is 1:1, and the mass ratio of the nickel source to PPy is 4.7:3.

[0016] Preferably, in step (2), the calcination temperature is 500 DEG C, and the calcination time is 2-6 h; further preferably, the calcination temperature is 500 DEG C, and the calcination time is 2 h.

[0017] Advantages

[0018] The application discloses a SnSe2-NiSe2 / CNT sodium ion battery negative electrode material and a preparation method thereof, and has the following advantages compared with the prior art.

[0019] 1. The three-dimensional structure prepared by the method has the original morphology of the carbon tube, and is doped with SnSe2-NiSe2 on the basis of the original morphology, and the hollow structure of the carbon material can have a certain buffering effect on the volume change in the charging and discharging process.

[0020] 2. The sodium ion battery negative material prepared by the method has high electron and ion transmission, and has good electrochemical performance.

[0021] 3. The preparation method provided by the application is simple and convenient, no waste liquid and waste material that cannot be treated are generated in the preparation process, is environmentally friendly, and has strong operability. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is an XRD pattern of the SnSe2-NiSe2 / CNT composite material obtained in Example 1;

[0023] Figure 2 is an SEM image of the SnSe2-NiSe2 / CNT composite material obtained in Example 1;

[0024] Figure 3 is a cycle performance graph of the battery prepared from the SnSe2-NiSe2 / CNT composite material obtained in Example 1. DETAILED DESCRIPTION

[0025] Hereinafter, the present application will be described in detail. Before proceeding with the description, it should be understood that the terms used in the specification and the appended claims should not be construed as limiting to the general and dictionary meanings and should be construed as carrying the meaning and concepts that are consistent with the technical scope of the present application based on the principles of the applicant's proper definition as suitable for the best explanation of the present application. Therefore, the description presented herein is merely a preferred example for the purpose of illustration and is not intended to limit the scope of the present application, so it should be understood that other equivalent ways or modifications can be derived from the present application without departing from the spirit and scope of the present application.

[0026] The following examples are merely listed as examples of embodiments of the present application and do not constitute any limitation on the present application, and those skilled in the art can understand that modifications within the scope of the spirit and concept of the present application fall within the scope of protection of the present application. Unless otherwise specified, the reagents and instruments used in the following examples are commercially available products.

[0027] Example 1

[0028] With nickel chloride hexahydrate and sodium citrate as initial raw materials, nickel chloride hexahydrate (0.47 g) and sodium citrate (0.51 g) were weighed according to the molar ratio of 1:1 and dissolved in deionized water, and then 10 ml of tin chloride pentahydrate ethanol solution was added dropwise to the above solution under vigorous stirring for 20 minutes, and then stirred for 30 minutes. Then 10 ml of NaOH solution was added and stirred for 30 minutes, and finally 0.3 g of PPy was added and stirred for 1 hour. The mixed solution was transferred to an autoclave together, heated at 160 ℃ for 8 h. The obtained sample was washed several times with deionized water and ethanol, and then completely dried to obtain a precursor; the obtained precursor was placed in a tube furnace and calcined at 500 ℃ for 2 h under inert gas to obtain SnO2-NiO2 / CNT; SnO2-NiO2 / CNT and selenium powder were weighed according to the mass ratio of 1:2, mixed and uniformly ground, and then annealed at 500 ℃ for 6 h under inert atmosphere to obtain the product SnSe2-NiSe2 / CNT composite material.

[0029] The XRD pattern of the obtained SnSe2-NiSe2 / CNT composite material is shown in Figure 1 , and it can be seen from Figure 1 that most of the main peaks can be perfectly matched with SnSe2-NiSe2 (the JCPDS card number of SnSe2 is 23-0602; the JCPDS card number of NiSe2 is 88-1711). There is no obvious peak of carbon, indicating that the carbon in the main body is amorphous.

[0030] The SEM image of the obtained SnSe2-NiSe2 / CNT composite material is shown in Figure 2 , and it can be seen from Figure 2 that PPy shows obvious tubular structure, and the diameter of the nanotube is about 350 nm. Many spherical nanoparticles are uniformly coated on the surface of the nanotube to form a uniform coating. The structure after compounding provides a high conductive network, which helps to inhibit the dendrite growth at the interface during the electrochemical process and improve the stability of the battery.

[0031] The prepared SnSe2-NiSe2 / CNT composite material was used as a negative electrode material of a sodium ion battery. The negative electrode material, acetylene black and PVDF were mixed according to the ratio of 7:2:1, and then a certain amount of solvent (N-methyl pyrrolidone) was added and mixed uniformly, followed by ball milling, drying, slicing, weighing, and then the prepared electrode sheet was used for battery assembly to obtain a battery for testing. The performance of the battery was tested as follows:

[0032] Test method: The battery test system recorded the charge and discharge test of the battery at 29°C (the window voltage range was 0.01-3V).

[0033] Test results: The cycle performance is shown in Figure 3As shown, at a current density of 0.5 A, the initial capacity is about 300 mA h g -1 The SnSe2-NiSe2 / CNT composite material exhibits good cycle stability in 100 cycles.

[0034] Example 2

[0035] Example 2

[0036] The prepared SnSe2-NiSe2 / CNT composite material was used as a negative electrode material for a sodium ion battery. The negative electrode material was mixed with acetylene black and PVDF in a ratio of 7:2:1, and a certain amount of solvent (nitromethyl pyrrolidone) was added and mixed uniformly, followed by ball milling, drying, slicing, and weighing. The prepared electrode sheet was used to assemble a battery for testing.

[0037] Example 3

[0038] Example 3

[0039] The prepared SnSe2-NiSe2 / CNT composite material is used as a negative electrode material of a sodium ion battery, the negative electrode material is mixed with acetylene black and PVDF in a ratio of 7:2:1, a certain amount of solvent (N-methyl pyrrolidone) is added dropwise, and then ball milling, drying, slicing, and tabletting are performed, an electrode sheet is prepared, and a battery is assembled using the electrode sheet to obtain a battery for testing.

[0040] The above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, the technical solutions recorded in the foregoing examples can still be modified or some technical features can be replaced by equivalents for ordinary skilled persons in the art; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions claimed by the present application.

Claims

1. A SnSe2-NiSe2 / CNT sodium-ion battery anode material, characterized in that, The negative electrode composite is formed by a tin source and a nickel source to form a composite SnSe2-NiSe2, and the composite SnSe2-NiSe2 is uniformly loaded on hollow carbon nanotubes; The composite SnSe2-NiSe2 is in a spherical particle form; The preparation method of the SnSe2-NiSe2 / CNT sodium ion battery negative electrode material comprises the following steps: (1) a nickel source and sodium citrate are sequentially dissolved in deionized water, SnCl4·5H2O ethanol solution is added dropwise under vigorous stirring, stirring and dissolving are performed, NaOH solution and PPy are added, heating treatment is performed at 160°C for 3h, the obtained sample is cleaned and dried to obtain a precursor; (2) the precursor obtained in step (1) is calcined under inert gas to obtain SnO2-NiO2 / CNT; (3) the SnO2-NiO2 / CNT obtained in step (2) is mixed with selenium powder and uniformly ground, and is annealed at 500°C under an inert atmosphere to prepare a SnSe2-NiSe2 / CNT composite sodium ion battery negative electrode material, wherein SnSe2-NiSe2 is uniformly loaded on CNT; In step (2), the calcination temperature is 500°C, and the calcination time is 2-6h.

2. The SnSe2-NiSe2 / CNT sodium-ion battery anode material of claim 1, wherein, In step (1) of the preparation method, the PPy is synthesized by mixing methyl orange, FeCl3, deionized water and pyrrole monomers, magnetically stirring at room temperature for 24h, centrifuging, washing and drying.

3. The SnSe2-NiSe2 / CNT sodium-ion battery anode material of claim 1, wherein, In step (1) of the preparation method, the nickel source is at least one of nickel chloride hexahydrate and nickel nitrate hexahydrate.

4. The SnSe2-NiSe2 / CNT sodium-ion battery anode material of claim 1, wherein, In step (1) of the preparation method, the molar ratio of the nickel source to sodium citrate is 1:1, the molar ratio of the nickel source to SnCl4·5H2O is 1:(1-2), the mass ratio of the nickel source to PPy is (4-5):3, and the concentration of the NaOH solution is 2moL / L.

5. The SnSe2-NiSe2 / CNT sodium-ion battery anode material of claim 1, wherein, In step (1) of the preparation method, the nickel source and sodium citrate are stirred for 20 minutes, SnCl4·5H2O ethanol solution is then added dropwise, stirring is continued for 30 minutes, NaOH solution is then added and stirred for 30 minutes, and finally PPy is added and stirred for 1 hour.

6. The use of a SnSe2-NiSe2 / CNT sodium-ion battery anode material according to claim 1, characterized in that, A negative electrode sheet for making a sodium ion battery.

7. Use of SnSe2-NiSe2 / CNT sodium-ion battery anode material according to claim 6, characterized in that, The electrode sheet comprises the following raw materials: a SnSe2-NiSe2 / CNT sodium ion battery negative electrode material, acetylene black, PVDF and a solvent; and the electrode sheet is prepared by mixing the SnSe2-NiSe2 / CNT sodium ion battery negative electrode material, acetylene black and PVDF according to a proportion, adding a certain amount of solvent dropwise, ball milling after uniform mixing, drying, slicing, weighing and slicing to obtain the electrode sheet.

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