A kind of lithium-sulfur battery composite cathode material and preparation method thereof

Abstract

The invention discloses a lithium-sulfur battery composite positive electrode material. Graphene oxide is used as a matrix of the battery positive electrode material, a graphene / ferroelectric composite material is obtained after the graphene oxide and a ferroelectric material are compounded, and then the graphene / ferroelectric composite material is mixed with nano sulfur according to a mass ratio of 3:7 to prepare the lithium-sulfur battery composite positive electrode material; and the ferroelectric material is one of barium titanate, lead titanate, potassium niobate, strontium titanate, lithium niobate or lead zirconate titanate. According to the lithium-sulfur battery composite positive electrode material disclosed by the invention, excellent electrical conductivity and structural stability of the graphene oxide are utilized, and the graphene oxide is used as an excellent conductive network and the positive electrode matrix, so that electrical conductivity of the positive electrode material is improved; and by utilizing strong adsorption of ferroelectricity of the ferroelectric material on polar polysulfide, dissolution and shuttling of the polysulfide in electrolyte are inhibited, so that loss of active substances is reduced, coulombic efficiency of a lithium-sulfur battery is improved and a cycle life of the lithium-sulfur battery is prolonged.

Description

technical field [0001] The invention belongs to the technical field of lithium-sulfur battery electrode materials, and in particular relates to a lithium-sulfur battery composite cathode material and a preparation method thereof. Background technique [0002] With the rapid development of society, human's demand for energy is increasing day by day. However, with the continuous exploitation of fossil fuels such as coal, oil, and natural gas, these resources have tended to be exhausted. At the same time, the excessive use of fossil fuels such as oil has produced a large amount of greenhouse gases, resulting in a global greenhouse effect and causing environmental problems that are difficult to solve. Based on the above resource and environmental issues, the development of new energy and renewable energy is particularly important. [0003] At present, the most widely commercialized lithium-ion battery has been increasingly unable to meet social requirements due to the capacity...

AI Technical Summary

Problems solved by technology

Although lithium-sulfur batteries have the above advantages, they also face some disadvantages, which hinder their practical application.

[0004] The main problem it faces is: the intermediate product produced during the charge and discharge process, that is, the polysulfide Li 2 S x (4≤x≤6) It is easily soluble in organic electrolyte, and the larger solubility not only leads to a decrease in the amount of active material and a decrease in the utilization rate of the sulfur cathode, but also increases the viscosity of the electrolyte and reduces the ion conductivity;

[0005] At the end of charging, the high-polymer polysulfides formed on the sulfur electrode diffuse to the lithium electrode, and react with lithium to form low-polymer polysulfides, and some insoluble Li 2 S 2 , Li 2 S will be deposited on the surface of the lithium sheet, and the soluble low-polymer polysulfide ions will diffuse to the sulfur cathode again to form high-polymer polysulfides. This process occurs repeatedly, resulting in a "shuttle effect", resulting in a sharp decrease in cycle performance. The cycle life is shortened and the Coulombic efficiency is reduced;