Quantum dot semi-interpenetrating network lithium-sulfur battery composite cathode material and preparation method

Abstract

The invention provides a preparation method of a quantum dot semi-interpenetrating network lithium-sulfur battery composite cathode material. The preparation method comprises the following steps: dispersing aluminum isopropoxide, polyacrylamide and graphene in isopropanol, thus obtaining dispersed glue solution; mixing zinc acetate, oleic acid and 1-octadecene, injecting a sulfur source and performing reaction, adding a sulfur elemental substance and a carbon source, dispersing at a high speed, further cooling, cleaning with deionized water and drying, thus obtaining a quantum dot ZnS / S / C compound; and adding the quantum dot ZnS / S / C compound into the dispersed glue solution, stirring for 1-2 hours, then performing spray drying, and performing de-polycondensation on aluminum isopropoxide inpresence of water to obtain a semi-interpenetrating network ZnS / S / C compound formed by alumina sol and polyacrylamide gel, thus the quantum dot semi-interpenetrating network lithium-sulfur battery composite cathode material is obtained. The preparation method provided by the invention adds sulfur and carbon in a process that zinc sulfide quantum dots are formed, and quantum dot sulfide and the sulfur elemental substance are combined, so that full participation of sulfur in electrolyte reaction is guaranteed, polysulfide shuttling is prevented, and volume expansion deformation is effectively prevented.

Description

Technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a quantum dot semi-interpenetrating network lithium-sulfur battery composite cathode material and a preparation method. Background technique [0002] Lithium-sulfur battery has a very high theoretical capacity. The theoretical specific capacity of the material and the theoretical specific energy of the battery are respectively 1672m Ah·g. -1 And 2600Wh·kg -1 At present, the actual energy density of lithium-sulfur batteries has reached 390Wh·kg -1 , Much higher than the highest specific capacity that can be achieved by traditional lithium-ion batteries. In addition to the very high energy density, lithium-sulfur batteries also have some other advantages. One is the use of sulfur and lithium as raw materials for production, and the production cost is relatively low; the second is that lithium-sulfur batteries are environmentally friendly and have low energy consumption for rec...

AI Technical Summary

Problems solved by technology

Although lithium-sulfur batteries have the advantages of high capacity and high specific energy, there are still some bottlenecks in existing lithium-sulfur batteries: (1) Elemental sulfur and its discharge product Li 2 S. Li 2 S 2 Both are electronic insulators with poor conductivity; (2) The intermediate product lithium polysulfide is easily soluble in the electrolyte and shuttles between the positive and negative electrodes, resulting in the loss of active materials and the reduction of Coulombic efficiency; (3) During the charging and discharging process , the interconversion between sulfur and lithium sulfide causes volume expansion and contraction, leading to the destruction of the electrode material structure

The use of carbon / sulfur composite structure can improve the conductivity of cathode materials, but it still cannot effectively capture polar polysulfides, and there is a risk of polysulfides dissolving into the electrolyte.

[0005] For this reason, technicians continue to explore methods that can effectively inhibit the shuttling of polysulfides, and further coat sulfur and carbon particles to effectively inhibit the shuttling of polysulfides. Chinese invention patent 201510118200.1 discloses a lithium-sulfur battery cathode material, preparation method and Lithium-sulfur batteries, using vacuum high-temperature carbonization of the microporous carbon coating layer and the carbon-sulfur composite material to form an interaction similar to "chemical bonds", so that the microporous carbon coating layer and the carbon-sulfur composite material are tightly combined, further Inhibit the dissolution of sulfur and discharge products in the electrolyte, prevent the "shuttle effect", and improve the utilization of sulfur. However, complete coating makes it difficult for the electrolyte to diffuse into the positive electrode material, thereby affecting the participation of sulfur in the charge-discharge reaction and affecting the capacity of lithium-sulfur batteries.