A kind of core-shell structure cobalt disulfide composite material and preparation method thereof

Abstract

The invention provides a method for preparing a core-shell structure cobalt disulfide composite material, comprising: S1) combining an organic acid cobalt salt, an organic sulfur source, a glycol solvent, cetyltrimethylammonium bromide and organic carbon Sources are mixed, and after hydrothermal reaction, an intermediate product is obtained; the organic sulfur source contains amino groups; S2) the intermediate product is mixed with sulfur powder, and annealed in a protective atmosphere to obtain a core-shell structure cobalt disulfide composite material. Compared with the prior art, the core-shell structure cobalt disulfide composite material prepared by the present invention has a good three-dimensional space structure, has an increased specific surface area and more reactive sites, and can also accommodate cobalt disulfide during desorption. The volume change when intercalating sodium ions buffers the internal stress caused by the volume change, prevents the pulverization of substances, and ensures its structural stability when used as a negative electrode material for sodium-ion batteries; the carbon layer on the surface enhances electronic conduction The ability to ensure the excellent electrochemical performance of cobalt disulfide.

Description

technical field [0001] The invention belongs to the technical field of sodium ion batteries, and in particular relates to a core-shell structure cobalt disulfide composite material and a preparation method thereof. Background technique [0002] Na-ion batteries have the characteristics of abundant sodium resources and low cost, which have attracted extensive attention from researchers at home and abroad, and are considered to be the best candidates for replacing lithium-ion batteries in the field of large-scale energy storage in the future. In recent years, the research on sodium-ion batteries has made important progress one after another, and the research system has been continuously enriched. However, due to the large ionic radius and slow kinetic rate of sodium ions, it has become the main factor restricting the development of sodium storage materials, and the development of high-performance sodium-intercalated anode materials is the key to improving the specific energy o...

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Problems solved by technology

Then, the conductivity of cobalt disulfide itself is low, and when it deintercalates sodium ions, it will undergo a huge volume change, or increase or decrease. Therefore, when pure cobalt disulfide is used as a negative electrode material for sodium ion batteries, there are two constraints. The key defect of capacity play: First, the conductivity of cobalt disulfide is very poor. When the battery is working, a large number of electrons and ions will be transferred and exchanged, while cobalt disulfide cannot perform this process quickly, and the electron conduction is slow. , Macroscopically, the internal resistance of the battery increases, the polarization is serious, and the capacity decay is extremely serious; secondly, when the sodium ions are intercalated, the volume of cobalt disulfide will increase by 300%, and when the sodium ions are extracted, the volume will increase again. Shrinking, such a drastic volume change will cause the cobalt disulfide materials to squeeze each other, resulting in internal stress concentration, and eventually cause the pulverization of the cobalt disulfide material. In terms of battery performance, it is shown that the battery is performing long-cycle charge and discharge tests. Severe capacity fading occurs at times, and the service life of the battery is shortened

[0007] Based on the existing patents and literature, it can be seen that the current anode materials for cobalt disulfide sodium ion batteries have problems such as complex preparation procedures and poor long-term battery cycle performance.

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