Preparation method of nitrogen-doped graphene/copper sulfide/hollow sulfur composite material

Abstract

The invention discloses a preparation method of a nitrogen-doped graphene / copper sulfide / hollow sulfur composite material. The preparation method comprises the following steps: step (1), adding powdered sulfur into carbon dioxide, stirring and dissolving to form a uniform solution; step (2), ball-milling high-purity nickel powder through a high-energy ball grinding mill, adding the high-purity nickel powder after ball-milling into the solution, stirring to form uniform suspension liquid, mechanically stirring, and carrying out spray drying to form sulfur clad spherical particles; step (3), adding the spherical particles into a ferric chloride solution, stirring for reaction, washing and filtering; and step (4), adding a filtered precipitate into a solution containing copper chloride, thioacetamide and a surface active agent, stirring to form uniform suspension liquid, heating and stirring for reaction, centrifuging and washing to obtain copper sulfide clad sulfur particles. In the composite material, a space is reserved for the volume expansion, in the charging and discharging process, of sulfur material through the design of a hollow structure, so that the electrochemical performance can be effectively improved.

Description

technical field [0001] The invention relates to the synthesis of nanomaterials, in particular to a preparation method of a positive electrode material of a lithium-sulfur battery. Background technique [0002] Lithium-sulfur battery is a battery system with metal lithium as the negative electrode and elemental sulfur as the positive electrode. Lithium-sulfur batteries have two discharge plateaus (about 2.4 V and 2.1 V), but their electrochemical reaction mechanisms are complex. Lithium-sulfur batteries have the advantages of high specific energy (2600 Wh / kg), high specific capacity (1675 mAh / g), and low cost, and are considered to be a promising new generation of batteries. However, at present, there are problems such as low utilization rate of active materials, low cycle life and poor safety, which seriously restrict the development of lithium-sulfur batteries. The main reasons for the above problems are as follows: (1) Elemental sulfur is an insulator of electrons and io...

AI Technical Summary

Problems solved by technology

This phenomenon, known as the shuttle effect, reduces the availability of sulfur active species

At the same time insoluble Li 2 S and Li 2 S 2 Deposited on the surface of the lithium negative electrode, which further deteriorates the performance of the lithium-sulfur battery; (3) the final product of the reaction, Li 2 S is also an electronic insulator and will be deposited on the sulfur electrode, while lithium ions migrate slowly in solid lithium sulfide, slowing down the electrochemical reaction kinetics; (4) sulfur and the final product Li 2 The density of S is different. When sulfur is lithiated, the volume expands by about 79%, which easily leads to Li 2 Pulverization of S, causing safety problems in lithium-sulfur batteries

The above deficiencies restrict the development of lithium-sulfur batteries, which is also a key issue that needs to be solved in current research on lithium-sulfur batteries.

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