High energy density supercapacitors with hierarchical nitrogen-doped porous carbon as active material obtained from bio-waste

Supercapacitors (SCs) is a promising energy storage approach to solve the intermittent problems of most renewable energy sources. N-doped hierarchically activated porous carbon materials (ACBS) for super capacitor applicaitons are obtained by pre-carbonization and KOH activation of N-rich sword bean shells. ACBS containing 1-2% of N show hierarchical porosity, very high surface area and pore volume (equal to 2917 m(2)/g and 1.73 cm(3)/g, respectively). These materials are incorporated into supercapacitors. The device containing ACBS obtained using 700 degrees C as a post-treatment temperature shows a very high specific capacity (equal to 264 F/g at 1 A/g), which remains high (similar to 180 F/g) even at 20 A/g current density. Corresponding symmetric coin-cell supercapacitor demonstrats 12.5 Wh/kg energy density at 100 W/kg power density. This cell is capable of maintaining its energy density at the 11.1 Wh/kg level at 5000 W/kg power density and demonstrats almost 100% capacity retention after one thousand 1 A/g charge/discharge cycles. Such superior electrochemical performance of devices fabricated using ACBS as active materials is possible because of synergy between electrical double-layer capacitance and faradaic pseudocapacitance, which strongly depend on the surface area, pore volume and size distribution as well as dopant of heteroatoams. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study focuses on N-doped hierarchically activated porous carbon materials (ACBS) for super capacitor applications, which exhibit high surface area and pore volume. The ACBS obtained using 700 degrees C as a post-treatment temperature shows high specific capacity at different current densities, demonstrating superior electrochemical performance.