Gelatinization assisted synthesis of multi-heteroatoms enriched 3D honeycomb-like porous carbon for high-voltage supercapacitor device

Abstract Developing high-performance supercapacitors with low-cost electrode materials that possess high power energy while maintaining high specific energy is highly desirable and remains a major challenge. Herein, we report an N, S, P-multi-heteroatom co-doped three-dimensional (3D) honeycomb-like porous carbon nanosheets from garden cress seeds via facile two-step synthesis strategy involving gelatinization accompanied by KOH activation. The large specific surface area (1302.3 m2 g−1) and hierarchical porous structure has advantages of a well-balanced 3D interconnected micro-/meso‑/ and macropores for shorter ion pathway and provide rapid electrolyte penetration. When the as-obtained doped porous carbon is used as a supercapacitor electrode, it delivered high specific capacitance of 409 F g−1 and 279 F g−1 in aqueous three and two-electrode configuration, respectively. In addition, the device shows high cyclic stability of 93% even after 10,000 cycles. More importantly, the assembled symmetric supercapacitor device using 1 M tetraethylammonium tetrafluoroborate (TEABF4) as organic electrolyte (2.8 V) delivered outstanding specific energy of 31 Wh kg−1 (6.2 Wh L−1) at a specific power of 1300 W kg−1 (260 W L−1) and retained 25 Wh kg−1 even at a high specific power of 3000 W kg−1. Notably, the high voltage fabricated supercapacitor was able to power up various light-emitting diodes of voltage range from 1.8 to 3.8 V demonstrating its potential towards powering electronic devices. The strategy to employ cost-effective renewable garden cress seeds as biomass precursors to achieve hierarchical porous multi-heteroatom doped 3D carbon is of great interest for high-performance energy storage applications.