Preparation and electrochemical performance of activation graphene/sulfur complex cathode material for lithium-sulfur batteries

Novel accordion structure activation graphene/sulfur (AG/S) complex cathode materials were prepared by solution-based reaction-deposition method using activation graphene (AG) as precursors. SEM, EDX and TEM measurement were conducted. The result indicated that the AG/S had accordion structure with a uniform S coating on accordion structure AG. At the same time, sulfur was also found to be deposited on the interlayer of AG. Constant current charge-discharge tests showed that the AG/S complex cathode material with 65wt% sulfur delivered a high initial discharge specific capacity of 1452.9 mAh/g at the current density of 400 mA/g, with 909.7 mAh/g remained after 200 cycles. Meanwhile, an initial discharge specific capacity of 1309.9 mAh/g could be obtained for the material at the larger current density of 1000 mA/g, keeping 717.1 mAh/g after 200 cycles at the same current density. The rate performance, coulombic efficiency and cycling stability of the AG/S complex cathode materials were confirmed to be excellent, which may be originated from the homogeneous distribution of the sulfur with small powder size in the composites, the excellent electrical conductivity of AG and the fixation effect of the functional groups on the surface of AG for S.