Effect of preparation conditions of Fe₂O₃-graphene-carbon nanotube composites on sulfur loading properties

Lithium sulfur battery is one of the most promising alternatives to traditional lithium-ion battery. The dissolution and poor conductivity of polysulfides are two important factors restricting the application of lithium sulfur battery. In this paper, Fe₂O₃-reduced graphene oxide (RGO)-carbon nanotube (CNT) composite sulfur carrying materials are synthesized by hydrothermal method. By adjusting the ammonia concentration, the particle size of Fe₂O₃ in the composites is successfully adjusted. It is found that Fe₂O₃ with small particles had better adsorption and catalysis. Cathode material synthesized from it at 1 C, the first discharge capacity is 1286 mA·h/g, 718 mA·h/g remains after 500 cycles, and the capacity attenuation rate of each cycle is 0.08%. The average specific capacities at 0.2, 0.5, 1, 2 and 4 C are 983, 825, 769, 673 and 604 mA·h/g, which has good rate performance and good cycle performance at high current. 527 mA·h/g remains after 500 cycles at 5 C. Fe₂O₃-RGO-CNT-S cathode material is especially suitable for high-performance lithium sulfur batteries. It has excellent electrochemical performance, mainly because the three-dimensional conductive network of RGO and CNT provides strong electron transmission path, rich pore structure, and sulfur is in full contact with the three-dimensional conductive network composed of RGO and CNT.