High performance supercapacitor electrodes based on B/N Co-doped biomass porous carbon materials by KOH activation and hydrothermal treatment

The N and B co-doped hierarchical porous carbon with excellent textured properties by using two-step of activation and hydrothermal post-treatment process using ammonium pentaborate tetrahydrate (NH4B5O8·4H2O) as both nitrogen and boron source are developed. The results showed that BNAC-3 has the maximum surface area (2471 m2/g) caused by the highest degree of micro/mesopores (0.82 and 0.35 cm3/g) and the linked 3D network are advantageous for the circulation of electrolytes and electrostatic adsorption. The contribution of Faradaic pseudocapacitance may be caused by high B (3.12 wt percent) and N (2.02 wt percent) contents of BNAC-3. Additionally, BNAC-3 exhibits excellent electrochemical efficiency with an ultra-high specific ability of 369 F/g at 1 A/g current density (CD) and maintains 240 F/g at 20 A/g in three-electrode systems. Notably, in a two-electrode device, maximum energy density can be almost 12.0 W h/kg at a power density (PD) of 375 W/kg.