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 (2741m(2)g(-1)), large specific pore volume (1.23cm(3)g(-1)), and well-controlled pore size distribution (0.6-5.0nm) were obtained and up to 65wt% 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.1200mAhg(-1)) was obtained, indicating a good sulfur utilization rate. An excellent discharge capacity (590mAhg(-1)) was also achieved for BPC-700-S65 at the high current rate of 4C (12.72mAcm(-2)), showing its extremely high rate capability. A reversible capacity of about 570mAhg(-1) was achieved for BPC-700-S65 after 500 cycles at 1C (3.18mAcm(-2)), indicating an outstanding cycling stability.