Nitrogen-doped porous carbon using ZnCl₂ as activating agent for high-performance supercapacitor electrode materials

A facile method for synthesising porous carbon materials with high nitrogen content is employed in this study using 1H-Benzotriazole (BTA) as carbon precursor and ZnCl₂ as active agent at 600–800 °C for 2 h under N₂ atmosphere. Pure BTA completely degrades even at low temperature (270 °C) under inert gas, but ZnCl₂ can convert the more organics to carbon because of its dehydration. The obtained NC-2-700 sample possesses a high specific surface area (1228 m²·g⁻¹) and a nitrogen content up to 10.27 wt%. Moreover, the N-doped carbon exhibits a good electrochemical property (with a specific capacitance of 332 F·g⁻¹ at the current density of 0.5 A·g⁻¹), as well as an outstanding cycle stability (96.5% of the initial specific capacitance is maintained after 5000 cycles at 1 A·g⁻¹). In addition, this obtained symmetric ultra-capacitor prepared from the NC-2-700 sample exhibits a highest energy density of 12.94 Wh·kg⁻¹ with a power density of 375 W·kg⁻¹ at a current density of 1 A·g⁻¹. And even this NC-2-700//NC-2-700 supercapacitor gives 5.43 Wh·kg⁻¹ with a power density of 3750 W·kg⁻¹ at a high current density of 10 A·g⁻¹. Consequently, these experimental results confirm that the porous carbon materials with high nitrogen content can be a prospective electrode material for supercapacitors.