One-pot molten salt-assisted synthesis of nitrogen-doped mesoporous carbon for high energy density supercapacitors

• N-doped mesoporous carbon has been prepared via one-pot molten salt-assisted method. • The obtained carbon exhibits a large specific surface area of 2960 m 2 g -1 . • Mesoporous carbon electrode presents high ion diffusion coefficient of 1.0×10 -8 cm 2 s -1 . • Symmetric supercapacitors show high energy density of 53.1Wh kg -1 in organic electrolyte. Porous carbon materials have drawn extensive attention as electrodes for supercapacitors (SCs) due to their tunable porous structure and large specific surface area (SSA). Generally, the pore engineering and heteroatom doping are common methods to improve the electrochemical performance of carbon-based SCs. Here, a simple one-step molten salt-assisted method is developed for constructing nitrogen-doped mesoporous carbon (NMPC). Under the optimized conditions, the prepared NMPC exhibits a high surface area of 2960 m 2 g -1 , a total pore volume of 1.69 cm 3 g -1 and the mesopore size distribution in the range of 2-5 nm. The large SSA and the mesopore-dominant porous structure greatly facilitate the ions transport (with a high diffusion coefficient of 1.0×10 -8 cm 2 s -1 ) and improve the capacitive performance of NMPC electrode. The optimized NMPC electrode delivers a specific capacitance of 308.5 F g -1 at 0.5 A g -1 and superior rate capability (200.0 F g -1 at 50.0 A g -1 ) in the aqueous alkaline electrolyte. Moreover, the symmetric SC assembled by NMPC achieves a high energy density of 53.1 Wh kg -1 at a power density of 375.1 W kg -1 in the TEABF 4 /acetonitrile electrolyte. This study provides a simple synthetic route to construct mesoporous carbon for SCs with high energy density.