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Carbon-coated nickel selenide ultrathin nanosheet composite material and preparation method thereof

A technology of composite materials and carbon nanosheets, applied in nanotechnology, nanotechnology, nanotechnology for materials and surface science, etc., can solve problems such as poor conductivity, poor cycle performance, low reversibility, etc., to improve conductivity , avoid stacking, alleviate the effect of volume expansion

Active Publication Date: 2020-07-28
JIANGSU UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Among these anode materials, oxides usually have low reversible ability; alloy anodes have large volume expansion during the intercalation / desodiation process, resulting in poor cycle performance; for metal selenides, their initial Coulombic efficiency is much higher than that of oxidation The cycle performance is more stable than that of sulfides and alloys, but its conductivity is poor and there are problems such as volume expansion during charging and discharging.

Method used

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  • Carbon-coated nickel selenide ultrathin nanosheet composite material and preparation method thereof
  • Carbon-coated nickel selenide ultrathin nanosheet composite material and preparation method thereof
  • Carbon-coated nickel selenide ultrathin nanosheet composite material and preparation method thereof

Examples

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Effect test

Embodiment 1

[0030] (1) Preparation of three-dimensional flower-like Ni(bim)(2-mim) precursor

[0031] 300 mg of nickel nitrate hexahydrate was dissolved in 20 mL of ethanol solution to form solution A. 830 mg of benzimidazole was dissolved in 20 mL of ethanol solution to form solution B. Solution C was formed by dissolving 830 mg of 2-methylimidazole into 20 mL of ethanol solution. Solution C was added dropwise to solution A under ultrasonication to form solution D. Then, solution B was added dropwise to solution D, stirred rapidly at room temperature for 30 minutes, washed with absolute ethanol three times, and dried in a blast drying oven at 120°C for 24 hours to obtain Ni(bim)(2-mim) .

[0032] (2) Preparation of carbon-coated nickel selenide NiSe@C

[0033] Take 200mg of Ni(bim)(2-mim) precursor and selenium powder and grind them evenly at a mass ratio of 1:2, and spread them on a porcelain boat. Calcination is then carried out under a pure argon atmosphere, the calcination tempe...

Embodiment 2

[0047] The difference from Example 1 is that the mass ratio of benzimidazole (830 mg) to 2-methylimidazole in step (1) is 1:2. The calcination temperature in step (2) is 650° C., and the yield of the obtained product is 60%. Test results: The three-dimensional nanoflower structure of NiSe@C is destroyed, and it is difficult to find a complete three-dimensional nanoflower structure. The thickness of the broken carbon sheet is about 15nm, and there are a large number of mesopores and macropores. Broken 3D nanoflowers cannot effectively suppress the volume expansion of NiSe, resulting in poor cycling stability.

Embodiment 3

[0049] The difference from Example 1 is that the mass ratio of benzimidazole (830 mg) to 2-methylimidazole in step (1) is 6:1. The calcination temperature in step (2) is 650° C., and the yield of the obtained product is 68%. Test results: NiSe@C is stacked by carbon nanosheets of different thicknesses, the thickness is about 30nm-50nm, no three-dimensional nanoflower structure is found, and there are a lot of micropores. Too thick carbon nanosheets are not conducive to the transport of Na ions, resulting in low specific capacity and poor rate performance.

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Abstract

The invention discloses a carbon-coated nickel selenide ultrathin nanosheet composite material. The composite material is composed of nickel selenide particles with the particle size of 150-350 nm andcarbon nanosheets with the thickness of 15-50 nm, the nickel selenide particles are coated with the carbon nanosheets, and the carbon nanosheets form a three-dimensional flower-like structure. The preparation method comprises the following steps of dropwise adding ethanol solution of 2-methylimidazole into ethanol solution of nickel nitrate hexahydrate while carrying out ultrasonic treatment, then dropwise adding ethanol solution of benzimidazole into mixed solution, carrying out sufficient stirring reaction at room temperature, washing with absolute ethyl alcohol to be clean, and drying to obtain a precursor; and uniformly grinding the precursor and selenium powder, calcining for 2-6 hours at 500-800 DEG C under the protection of argon, and naturally cooling to room temperature to obtainNiSe-C powder. According to the NiSe-C nanoflower composite material prepared by the method, a problem of volume expansion of a metal selenide electrode material in the charging and discharging process can be effectively relieved, and cycle performance of a battery is improved.

Description

technical field [0001] The invention relates to a carbon-coated nickel selenide ultra-thin nanosheet composite material and a preparation method thereof, belonging to the technical field of nanocomposite materials. Background technique [0002] Lithium-ion batteries (LIBs) have been widely used in our daily life due to their good electrochemical performance and mature production process, but they cannot be used for a long time due to the low reserve and high cost of lithium resources. Since sodium-ion batteries (SIBs) are rich in sodium salts and low in cost, many researchers have shifted their attention from LIBs to SIBs. SIBs and LIBs have a similar intercalation mechanism, but Na + Larger radii and poorer diffusion in the host material make it difficult to achieve good rate capability. For the development of SIBs, the main bottleneck lies in finding electrode materials with stable cycling performance and excellent rate capability. [0003] Electrode materials such as o...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/58H01M4/583H01M4/62H01M10/054B82Y30/00
CPCH01M4/366H01M4/581H01M4/583H01M4/625H01M10/054B82Y30/00H01M2004/027Y02E60/10
Inventor 陈家乐张俊豪苏冬芹郭兴梅蔡星伟薛艳春万小晗
Owner JIANGSU UNIV OF SCI & TECH
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