Biomass-Derived Porous Carbon with Micropores and Small Mesopores for High-Performance Lithium-Sulfur Batteries.

Biomass-derived porous carbon BPC-700, incorporating micropores and small mesopores, was prepared through pyrolysis of banana peel followed by activation with KOH. A high specific BET surface area (2741 m  g ), large specific pore volume (1.23 cm  g ), and well-controlled pore size distribution (0.6-5.0 nm) were obtained and up to 65 wt % sulfur content could be loaded into the pores of the BPC-700 sample. When the resultant C/S composite, BPC-700-S65, was used as the cathode of a Li-S battery, a large initial discharge capacity (ca. 1200 mAh g ) was obtained, indicating a good sulfur utilization rate. An excellent discharge capacity (590 mAh g ) was also achieved for BPC-700-S65 at the high current rate of 4 C (12.72 mA cm ), showing its extremely high rate capability. A reversible capacity of about 570 mAh g was achieved for BPC-700-S65 after 500 cycles at 1 C (3.18 mA cm ), indicating an outstanding cycling stability.