阅读说明：本技术 一种碳包覆二硫化锗及其制备方法与应用 (carbon-coated germanium disulfide and preparation method and application thereof ) 是由 欧星 肖志明 王春辉 张佳峰 张宝 于 2019-10-31 设计创作，主要内容包括：一种碳包覆二硫化锗及其制备方法与应用。本发明碳包覆二硫化锗的通式为GeS<Sub>2</Sub>@C,其呈直径为400~600nm的空心球,表层由碳包覆。本发明制备方法,将锗源溶液、聚苯乙烯小球和碳源分散均匀形成悬浊液,冷冻干燥得到前驱体,然后将前驱体在惰性气氛下进行碳化,得到碳化材料,最后将碳化材料在还原气氛下硫化,得到碳包覆二硫化锗。本发明碳包覆二硫化锗呈空心球状结构,可有效缓解采用其制备的负极材料在充放电过程因体积膨胀引起的结构破坏,提高负极材料的循环稳定性。本发明制备方法操作简单,能够制备得到呈空心球状结构的碳包覆二硫化锗。(carbon-coated germanium disulfide, and preparation method and application thereof, the general formula of the carbon-coated germanium disulfide is GeS 2 @ C, which is a hollow sphere with a diameter of 400-600 nm, the surface layer of which is coated with carbon. The preparation method comprises the steps of uniformly dispersing a germanium source solution, polystyrene spheres and a carbon source to form a suspension, carrying out freeze drying to obtain a precursor, carbonizing the precursor in an inert atmosphere to obtain a carbonized material, and vulcanizing the carbonized material in a reducing atmosphere to obtain the carbon-coated germanium disulfide. The carbon-coated germanium disulfide is in a hollow spherical structure, so that structural damage of the cathode material prepared by the carbon-coated germanium disulfide due to volume expansion in the charging and discharging processes can be effectively relieved, and the cycling stability of the cathode material is improved. The preparation method is simple to operate, and the carbon-coated germanium disulfide with the hollow spherical structure can be prepared.)

1, carbon-coated germanium disulfide, which is characterized in that the general formula is GeS₂@ C, which is a hollow sphere with a diameter of 400-600 nm, the surface layer of which is coated with carbon.

2. The method for preparing carbon-coated germanium disulfide according to claim 1, wherein a germanium source solution, polystyrene beads and a carbon source are uniformly dispersed to form a suspension, freeze-drying is performed to obtain a precursor, then the precursor is carbonized under an inert atmosphere to obtain a carbonized material, and finally, the carbonized material is vulcanized under a reducing atmosphere to obtain carbon-coated germanium disulfide.

3. The method of claim 2, wherein the carbonization temperature is 400 ℃ to 800 ℃; more preferably, the carbonization temperature is 700 ℃; preferably, the carbonization time is 1-24 h; more preferably, the carbonization time is 2-19 h; more preferably, the carbonization time is 2-10 h.

4. The method for preparing carbon-coated germanium disulfide according to claim 2 or 3, wherein the temperature of vulcanization is 300-900 ℃; more preferably, the vulcanization temperature is 400-800 ℃; more preferably, the temperature is 600-700 ℃; preferably, the vulcanizing time is 0.5-20 h; more preferably, the vulcanizing time is 1-15 h; more preferably, the vulcanizing time is 2-8 h.

5. The method of claim 2 to 4 and , wherein the polystyrene spheres have a diameter of 50 to 900 nm.

6. The method of any , wherein the carbon source is selected from one or more of graphene oxide, carbon nanotubes and graphite .

7. The method of , wherein the mass ratio of the germanium source, the polystyrene beads and the carbon source in the germanium source solution is 0.1-0.4: 0.15-0.4: 0.01-0.075.

8. The method of claim 2-7 or , wherein the reducing atmosphere is a mixture of argon and hydrogen.

9. The method for preparing carbon-coated germanium disulfide according to any one of claims 2-8, wherein the germanium source solution is prepared by dispersing a germanium source in a solvent, adding ammonia water to assist dissolution, and then adjusting the pH value to 0.5-4 to obtain a germanium source solution, preferably, the germanium source is selected from or more of germanium powder, germanium chloride, germanium dioxide and germanium oxide, preferably, the concentration of the germanium source in the germanium source solution is 1.25-20 g/L, preferably, the concentration of ammonia in the germanium source solution is 0.32-12.85 mol/L, preferably, the solvent in the germanium source solution is selected from or more of water, methanol, ethanol and ethylene glycol, and preferably, the pH value adjusting agent is 5-40 wt% hydrochloric acid.

10, sodium battery cathode materials, which is characterized in that the carbon-coated germanium disulfide is prepared by the preparation method of claim 1 or of claims 2-9.

Technical Field

The invention belongs to the field of lithium/sodium battery cathode materials, and particularly relates to carbon-coated germanium disulfide and a preparation method and application thereof.

Background

As the lithium ion battery has the excellent performances of long cycle life, light weight, small volume, high energy, good stability, safety, reliability and the like, the lithium ion battery has been widely applied in the field of high-tech products such as new energy automobiles, mobile phones and other digital products, however, along with the continuous consumption of the lithium resource, the deficient lithium resource seriously limits the wide-range application of the future lithium ion battery.

The negative electrode materials of lithium ion batteries with high capacity are developed to date, such as metal oxides, metal sulfides and the like, but the ionic radius of sodium ions is larger than that of the lithium ion batteries, so that the electrode materials suitable for the lithium ion batteries are not suitable for the sodium ion batteries.

Disclosure of Invention

The invention aims to overcome the defects and provide carbon-coated germanium disulfide, and a preparation method and application thereof.

The technical scheme adopted by the invention for solving the technical problems is as follows:

kinds of carbon coated germanium disulfide with general formula GeS₂@ C, which is a hollow sphere with a diameter of 400-600 nm, and the surface layer is coated with amorphous carbon.

preparation method of carbon-coated germanium disulfide, which comprises the steps of dispersing a germanium source solution, polystyrene spheres and a carbon source uniformly to form a suspension, freeze-drying to obtain a precursor, carbonizing the precursor in an inert atmosphere to obtain a carbonized material, and finally vulcanizing the carbonized material in a reducing atmosphere to obtain the carbon-coated germanium disulfide.

Preferably, the carbonization temperature is 400-800 ℃. More preferably, the carbonization temperature is 700 ℃.

Preferably, the carbonization time is 1-24 h. More preferably, the carbonization time is 2-19 h. More preferably, the carbonization time is 2-10 h.

Preferably, the vulcanizing temperature is 300-900 ℃. More preferably, the vulcanization temperature is 400-800 ℃. More preferably, the temperature is 600-700 ℃.

Preferably, the vulcanizing time is 0.5-20 h. More preferably, the vulcanizing time is 1-15 h. More preferably, the vulcanizing time is 2-8 h.

Preferably, the diameter of the polystyrene pellet is 50-900 nm.

Preferably, the carbon source is or more selected from Graphene Oxide (GO), Carbon Nanotubes (CNT) and graphite.

Preferably, the mass ratio of the germanium source, the polystyrene spheres and the carbon source in the germanium source solution is 0.1-0.4: 0.15-0.4: 0.01-0.075.

Preferably, the gas used in the reducing atmosphere is a mixed gas of argon and hydrogen.

Preferably, the preparation method of the germanium source solution comprises the following steps: dispersing a germanium source in a solvent, adding ammonia water for assisting dissolution, and then adjusting the pH value to 0.5-4 to obtain a germanium source solution.

Preferably, the germanium source is selected from or more of germanium powder, germanium chloride, germanium dioxide and germanium oxide.

Preferably, the concentration of the germanium source in the germanium source solution is 1.25-20 g/L.

Preferably, the concentration of ammonia in the germanium source solution is 0.32-12.85 mol/L.

Preferably, in the germanium source solution, the solvent is or more selected from water, methanol, ethanol and ethylene glycol.

Preferably, the reagent for adjusting the pH value is 5-40 wt% of hydrochloric acid.

negative electrode material of sodium ion battery, which is characterized in that the negative electrode material comprises carbon-coated germanium disulfide or carbon-coated germanium disulfide prepared by the preparation method of the carbon-coated germanium disulfide.

The invention has the beneficial effects that:

(1) the carbon-coated germanium disulfide is of a hollow sphere structure, and the battery cathode prepared by the carbon-coated germanium disulfide can effectively buffer the volume expansion of the germanium disulfide in the charging and discharging processes, so that the structural damage of the cathode material is prevented, and sodium ions are enabled to be in GeS₂The intercalation and deintercalation are fast and effectively carried out, the structural integrity of the cathode material is kept, and the rate capability and the cycling stability of the electrode material are effectively improved;

(2) according to the method, a germanium source and a carbon source are used as raw materials, polyethylene beads are used for adsorbing the germanium source and the carbon source to form coated beads, and then carbonization and vulcanization are sequentially carried out, so that germanium disulfide is coated in the beads to form a stable three-dimensional structure, and the carbon-coated germanium disulfide in a hollow spherical shape is obtained; the method has the advantages of simplicity, uniform product distribution, high productivity, high resource utilization rate, low cost and small influence on the environment.

Drawings

Figure 1 is an XRD pattern of carbon-coated germanium disulfide prepared in example 1 of the present invention;

FIG. 2 is an SEM image of carbon-coated germanium disulfide prepared in example 1 of the present invention;

FIG. 3 is a graph of the cycle performance of a negative electrode material prepared using carbon-coated germanium disulfide prepared in example 1 of the present invention;

figure 4 is an SEM image of germanium disulfide prepared in comparative example 1 of the present invention.

Detailed Description

The present invention will be further described in with reference to the following examples and the accompanying drawings.