Preparation and electrochemical performance of a hierarchically porous activated carbon aerogel/sulfur cathode for lithium-sulfur batteries

An activated carbon aerogel with a hierarchical pore structure was prepared through KOH activation with a KOH/organic aerogel with mass ratio 3∶1, followed by carbonization at 900℃ for 3 h. The activated carbon aerogel was used as a conductive host of elemental sulfur to prepare a composite by a melt-infiltration method. Nitrogen adsorption, SEM, TEM, XRD and XPS were used to characterize the structure and morphology of the samples before and after the sulfur infiltration. Cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy were used to evaluate the electrochemical performance of the composite as a cathode in lithium ion batteries. It is found that the composite has a sulfur content of up to 66.2%, a high initial discharge capacity of 1 287 mAh·g^-1 at a current density of 0.2 C and a retained capacity of 643 mAh·g^-1 after 200 cycles, which are much higher than those of a sulfur cathode without the carbon host. The composite also exhibits excellent rate capability.