Hierarchical carbon microtubes from willow catkins for Li–S batteries

Abstract It is crucial but quite challenging to cycle carbon waste to prepare useful carbon material for energy storage by green process. Herein, hierarchical porous carbon microtubes synthesized by directly heating willow catkins without activation were used for Li–S batteries. The carbon microtubes loaded >75.0% sulfur were used as the Li–S battery cathodes. The cathodes with high areal sulfur content of 2.6 mg/cm2 deliver an initial discharge capacity of ~800 mAh/g at 0.5 C, and stabilized at 624 mAh/g after ~150 cycles at 0.5 C, with a low degradation rate per cycle (0.13% after 150 cycles or 0.07% after 1000 cycles). Our investigation presents that the fly willow catkins air-contaminants could be collected to use for high-density energy storage.