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 2  g −1 ), large specific pore volume (1.23 cm 3  g −1 ), 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 −1 ) was obtained, indicating a good sulfur utilization rate. An excellent discharge capacity (590 mAh g −1 ) was also achieved for BPC‐700‐S65 at the high current rate of 4 C (12.72 mA cm −2 ), showing its extremely high rate capability. A reversible capacity of about 570 mAh g −1 was achieved for BPC‐700‐S65 after 500 cycles at 1 C (3.18 mA cm −2 ), indicating an outstanding cycling stability.