In-situ conversion of waste biomass into heteroatoms (N, O)-doped 3D porous carbon for colossally efficient electric double-layer capacitor

The charge storage performance of porous carbon could be improved by employing amassed redox active sites on its surface via heteroatom doping. Herein, the cavity mediation strategy is introduced to synthesize one-step heteroatom-doped porous carbon for supercapacitors. The heteroatom-doped porous carbon reveals decent micro/meso surface contributions with a high surface area (1254 m2g- 1). It shows a tremendous specific capacitance of 482 F g- 1 as compared to without nitrogen-doped porous carbon (270 F g- 1). In contrast, the heteroatom-doped porous carbon sustains attractive cycling retention performance as 96.5 %@ 25 A g- 1, 95 % @40 A g- 1, and 92.7 %@ 50 A g- 1 for 15 K, 18 K & 20 K Galvanostatic charge-discharge cycles, respectively. Moreover, the heteroatom-doped porous carbon electrodes-based symmetric supercapacitor device is fabricated in coin cell mode using PVA/KOH gel electrolyte. The device discloses a high energy density of 42.3 W h Kg- 1 at 796 W Kg- 1 power density. Alongside, it facilitates moderate cycling stability of 90 % with coulombic efficiency >= 99 % up to long-term rigorous 50 K charge discharge cycles at 16 A g- 1. Furthermore, a practical demonstration is also carried out by illuminating red and green LEDs with good brightness. This "waste to wealth" approach is truly practicable in achieving the colossal supercapacitive behavior of porous carbon to foster a sustainable energy storage system.