Method for preparing titanium oxide coated sulfur-doped carbon nanotube lithium-sulfur battery cathode material

Abstract

The invention belongs to the field of electrode materials and in particular to a method for preparing a titanium oxide coated sulfur-doped carbon nanotube lithium-sulfur battery cathode material. Themethod comprises firstly adding a carbon nanotube into deionized water, performing a dispersing process, adding a sodium sulfide solution, adding a resultant solution to a reaction kettle, performinga thermostatic reaction, centrifugal separation, washing, and vacuum drying to obtain a sulfur-doped carbon nanotube; and finally, adding a solution A composed of concentrated ammonia water, tetraethyl titanate, and a organic solvent to the sulfur-doped carbon nanotube dispersion liquid, performing constant-temperature stirring, centrifugal separation, washing, vacuum drying and calcination to obtain the titanium dioxide coated sulfur-doped carbon nanotube. The method for preparing the titanium dioxide coated sulfur-doped carbon nanotube is easy to operate and low in economic cost and can realize large-scale production. The prepared titanium dioxide coated sulfur-doped carbon nanotube has large specific surface area, high electron transport capacity and first charge and discharge capacity,and excellent cycle performance.

Description

technical field [0001] The invention belongs to the field of electrode materials, and in particular relates to a preparation method of a titanium dioxide-coated sulfur-doped carbon nanotube lithium-sulfur battery cathode material. Background technique [0002] In recent years, the rapid development of the global economy has increased the demand for energy and the environmental pollution has become increasingly serious. The development of secondary batteries with high energy density, long cycle life, high safety, green environmental protection and low cost is of great significance in the field of new energy. Lithium-sulfur battery is a kind of secondary battery system under development with relatively high energy density. It uses elemental sulfur or sulfur-containing materials as the positive electrode active material, and its theoretical energy density reaches 2600Wh / kg. Friendly, cheap and other advantages. [0003] However, there are still some problems in lithium-sulfur ...

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Problems solved by technology

[0003] However, there are still some problems in lithium-sulfur batteries at present, which seriously hinder the practical application of lithium-sulfur batteries. Under the extremely low conductivity (conductivity is only 5.0×10 -30 S cm -1 ), the final product of the reaction is polysulfide, which can be dissolved in the electrolyte, causing the capacity fading of lithium-sulfur battery to drop sharply, resulting in poor cycle performance of the battery, which is not conducive to the high rate performance of the battery; secondly, the sulfur and lithium sulfide Density is 2.36g cm -3 and 1.66g cm -3 , there is a volume expansion or contraction of up to 42% during charge and discharge, this expansion will lead to changes in the morphology and structure of the positive electrode, resulting in the detachment of sulfur from the conductive framework, resulting in capacity attenuation

[0005] However, when the carbon network channels are used to load elemental sulfur, the carbon cannot restrain the polysulfides, and the polysulfides are still soluble in the electrolyte, which makes the capacity fading of the lithium-sulfur battery drop sharply, resulting in poor cycle performance of the battery.

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