One step activation by ammonium chloride toward N-doped porous carbon from camellia oleifera for supercapacitor with high specific capacitance and rate capability

In recent years, various biomasses (such as coconut, cotton, wheat straw, basswood, bamboo, etc.) have been utilized to prepare porous carbon materials (PCMs) through carbonization and/or physical/chemical activation. Most of these carbon materials are limited by the electric double-layer capacitance, resulting in a limited specific capacitance. Moreover, the preparation processes are often complicated and the carbon yield is low. Therefore, from the perspective of green and sustainable preparation of PCMs with high carbon yield and high performance, in this study, N-doped porous carbon electrodes were prepared by one-step activation carbonization method using camellia oleifera branches as raw material and NH 4 Cl as the activator. The N-doped NCW-2 sample has a rational hierarchical porous structure and high N doping amount (3.35 at. %) and exhibited optimal rate performance with a specific capacitance of 250 F g −1 at 50 A g −1 . The symmetrical device also presented excellent performance with a capacitance retention of 93.7 % after cycling 30,000 times at 20 A g −1 and delivered superior rate performances of 22.3 W h kg −1 @100 W kg −1 to 11.8 W h kg −1 @4800 W kg −1 . This work may provide a certain reference for the preparation of N-doped biomass-derived PCMs and widen its practical application in supercapacitor devices. • The self-supporting N-doped porous carbon can be directly used without posttreatment. • The mechanism of doping and activation are preliminarily proposed. • The as-prepared material has a high nitrogen doping of 3.35 at. %. • Electrodes exhibited a high specific capacitance of 250 F g −1 even at 50 A g −1 . • The symmetrical device showed a capacitance retention of 93.7 % after 30,000 cycles.