From basil seed to flexible supercapacitors: Green synthesis of heteroatom‐enriched porous carbon by self‐gelation strategy
Hanwen Yang, Jie Zhou, Mengqi Wang, Shengji Wu, Wei Yang, Hui Wang
Abstract
Basil seed-derived multi-heteroatom–doped porous carbons (BHPCs) are successfully synthesized by a facile gelation, followed by a moderate gel water/KOH coactivation process. The BHPC-700 prepared at a relatively low KOH loading and activation temperature possesses large specific surface area (1178.3 m2 g−1), well-defined hierarchical micro/meso porosity, and rich self-doping heteroatom functionalities (13.08 at% of oxygen, nitrogen, phosphorous, and sulfur). Electrochemical tests demonstrate that the BHPC-700–based electrode achieves an ultrahigh specific capacitance (464 F g−1 at 0.5 A g−1), outstanding rate performance (retaining 73.3% capacitance at 50 A g−1), and superior cyclic stability (96.8% capacitance retention over 5000 cycles). Furthermore, the BHPC-700 electrodes are assembled into all-solid-state symmetrical supercapacitors. The as-assembled device gives a high energy density of 15.0 Wh kg−1 at a power density of 500 W kg−1 and remarkable flexibility, demonstrating great application prospects in the area of sustainable portable electronics.