Preparation And Properties Of Cathode Composites Of Lithium-Sulfur Battery

Lithium-sulfur battery is a promising energy storage system due to its high theoretical energy density, low cost and environmental friendliness. However, there are some problems in Lithium-sulfur batteries, such as a low active material utilization and poor cycle life because of a high electrical resistivity of sulfur and lithium sulfide, and the high solubility of the charge-discharge products in the electrolytes. In this article, different cathode active materials were designed to improve the electrochemical properties of Lithium-sulfur battery.(1)Cathodes materials of lithium-sulfur batteries were synthesized by heating element sulfur with acetylene black, KS6 and carbon nanotubes respectively. The results show that when the S/AB ratio is 4:1, the highest initial discharge capacity of the S/AB cathodic composite reaches 899.86 mAh/g in the current rate of 0.1C,but its coulombic efficiency is only 38.45% after 20 cycles. It says that acetylene black of granular structure can not prevent the loss of substance active substances. The carbon nanotubes is more suitable for cathodic materials of lithium-sulfur batteries in all three carbon materials of different structures,and its initial discharge capacity is 1286 mAh/g at the current rate of 0.1C.(2)Cathodic materials of lithium-sulfur batteries were synthesized by heating element sulfur with titania nanoparticles and titania nanotube respectively. The results show that the properties of S/TiO2 composite cathode material is excellent, and its initial discharge capacity which sulfur contributed is about 1020mAh/g, and its discharge capacity which sulfur contributed has a excellent cyclic retention of about 85% after three cycles. The properties of S/TNT cathodic composite is modest, and its initial discharge capacity which S contributed is only about 720mAh/g, and its discharge capacity which sulfur contributed has a excellent cyclic retention of about 65% after 3 cycles.(3) S/MC cathodic composite of lithium-sulfur batteries were synthesized by sulfur with mesoporous carbon, and its initial discharge capacity is 1265mAh/g in the current rate of 0.1C.The discharge capacity is also 565.20mAh/g after 50 cycles.