Nitrogen and oxygen co-doped carbon networks with a mesopore-dominant hierarchical porosity for high energy and power density supercapacitors

Nitrogen and oxygen co-doped hierarchical porous carbon (N, O-HPC) networks has been synthesized using cattle bones as precursors via pre-carbonization and carbonization combined with KOH activation. The effects of carbonization and activation temperature on the physiochemical and electrochemical performances of the N, O-HPCs were systematically studied. The N, O-HPC obtained at 850 degrees C (referred to as N, O-HPC-850) possesses a mesopore-dominant hierarchical porous network with a large specific surface area (2520 m(2) g(-1)), a relatively high content of N (1.56%) and O (10.2%) and a good electrical conductivity (421.9 S m(-1)). As it is used as supercapacitor electrode material, N, O-HPC-850 exhibits a large specific capacity (444 F g(-1) at a scan rate of 5 mV s(-1) and 435 F g(-1) at a current density of 0.1 A g(-1), respectively) and good rate performance (252 F g(-1) at a scan rate of 500 mV s(-1) and 309 F g(-1) at a current density of 20 A g(-1), respectively) in 6 M KOH solution. Moreover, the assembled symmetric supercapacitor based on N, O-HPC-850 electrode delivers the energy density of 30.3 and 9.7 Wh kg(-1) at the power density of 0.341 and 43.8 kW kg(-1), respectively, and exhibits a good cycling stability with a capacitance retention of 97.5% after 20000 cycles in 1 M Na2SO4 solution. (C) 2017 Elsevier Ltd. All rights reserved.