A novel way to synthesize nitrogen doped porous carbon materials with high rate performance and energy density for supercapacitors

We report a novel, facile method for the synthesis of nitrogen doped porous carbon with three-dimensional interconnected porous framework by one-step pyrolysis of the mixture of agar, potassium citrate and urea. The optimized material possesses large specific surface area, interconnected porous framework and massive heteroatom functional groups. As an electrode material, it delivers a high specific capacity of 357 F g⁻¹ at 1 A g⁻¹, good rate performance (267 F g⁻¹ at 50 A g⁻¹) and good electrochemical stabilization (95.6% initial capacitance retained after 10,000 cycles) in 6 M KOH solution. Moreover, the as-prepared symmetric supercapacitor based on the NPC electrodes shows an energy density of 24.1 Wh Kg⁻¹ between the voltage ranges of 0–1.8 V in 1 M Na₂SO₄ solution, comparable with most of reported carbon-based symmetric supercapacitors. More immortally, even at a high power density of 12.5 kW kg⁻¹, it still remains an energy density of 12.5 Wh kg⁻¹. Therefore, this paper provides a facile, sustainable method for the synthesis of heteroatom doped three-dimensional interconnected porous carbon materials for high performance supercapacitors.