High-performance hierarchical N-doped porous carbons from hydrothermally carbonized bamboo shoot shells for symmetric supercapacitors

Abstract Biomass-derived porous carbons have become the most competitive electrode materials for supercapacitor due to their renewability and sustainability. Here we report a facile method to synthesize N-doped hierarchical carbons from hydrothermal carbonization followed by a mild KOH activation, using agricultural biowastes of bamboo shoot shells as raw materials and melamine as nitrogen source. The pore structure and surface-doping chemistry of carbons can be easily adjusted by changing activation temperature, showing surface areas of ∼3300 m2/g with main mesopores centering at ∼2.8 nm. The carbons used as electrodes for supercapacitor showed excellent capacitive performance with capacitance of 209 F/g in 6 M KOH electrolytes at 0.5 A/g, and remained to be 188 F/g even at high current density of 10 A/g. In addition, the as-assembled supercapacitor also exhibited superior cycling stability with capacity retention of 95% at 10 A/g even after 10,000 cycles. The effective carbon conversion from the discarded biowastes exhibits great potential in resources recycles for energy storage supercapacitors.