Lithium-sulfur secondary battery, because of its advantages of theoretical specific capacity and specific energy (specific capacity: 1675Ah kg-1, specific energy: 2600Wh kg-1), and the cathode active substance elemental sulfur is rich in resources and environment-friendly, is considered to be one of the most promising secondary battery systems with an energy storage potential of 300 W h • kg-1. In recent years, with the rise of large-scale high-capacity electrochemical energy storage applications such as electric vehicles and energy storage power plants, the research on lithium-sulfur secondary batteries has been widely concerned, and the research on the reversible properties of materials and electrochemistry of sulfur electrodes has been studied Has become one of the hot spots of high energy chemical energy exploration.
At present, there are still many problems for lithium-sulfur battery to achieve commercial applications. First, at room temperature, the elemental sulfur and its discharge product conductivity is very low, the latter will gather in the collector and the electrode within the conductive mesh surface, reducing its conductivity. Secondly, the "shuttle phenomenon" seriously affects the material properties.During charge and discharge process, intermediate product polysulfide Sn2- (n> 3) can easily soluble in the electrolyte, and through the membrane to generate insoluble Li2S2 and Li2S with metal lithium negative electrode. Once the metal lithium negative is completely covered, Li2S2 and Li2S on the urface will form S (n-x) 2- with Sn2-, S (n-x) 2- will diffuse back to the positive electrode and be oxidized to Sn2- again, and the sulfur utilization and cycle performance are reduced.
The focus of this research group is to use the carbon material composite, adding new additives and metal chemical bonding and other physical or chemical methods or the effective combination of the two methods to inhibit the polysulfide "shuttle effect" to improve the lithium-sulfur secondary battery Cycle performance and rate characteristics.
