以经活化处理的石墨烯(AG)为主体材料,通过化学还原法制备了石墨烯负载硫的复合正极材料 AG/S。SEM、EDX和TEM测试结果表明经活化处理后形成手风琴结构的AG,有利于电解液的浸润；活性物质硫均匀地负载在AG表面,同时沉积在AG的层间。电化学测试表明：在400 mA/g电流密度下, AG/S复合正极材料首次放电比容量为1452.9 mAh/g,经过200次循环之后,放电比容量仍保持在909.7 mAh/g；在1000 mA/g电流密度下, AG/S复合材料首次放电比容量为1309.9 mAh/g,经过200次循环之后,放电比容量仍保持在717.1 mAh/g。AG/S复合正极材料的倍率性能、库仑效率和循环性能优异,这得益于小尺寸的硫在材料中均匀分布,活化石墨烯优良的导电性以及其结构对硫的固化作用。
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 mate-rial 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 con-firmed 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.
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