High performance aqueous supercapacitor based on highly nitrogen-doped carbon nanospheres with unimodal mesoporosity

Herein, we report a high performance aqueous supercapacitor which is made of highly nitrogen-doped carbon nanospheres (NRMCs) with unimodal mesoporosity. An aerosol-assisted spraying process is employed to obtain the nano-sized NRMC particles possessing large surface areas, high pore volumes and ultra-high N doping levels (14.51%–20.55%). Evaluated as supercapacitor electrode, the optimized NRMC exhibits excellent performance for aqueous electrical double layer capacitors with high material-level specific capacitance (432 F g⁻¹ at 1 A g⁻¹), excellent rate performance (205 F g⁻¹ at a high current density of 100 A g⁻¹) and high cycling stability. The constructed symmetric supercapacitor delivers high energy densities of 9.2 Wh kg⁻¹ and 4 Wh kg⁻¹ at power densities of 0.11 kW kg⁻¹ and 23.24 kW kg⁻¹, respectively. Moreover, the effect of N specie distribution on the rate performance is also demonstrated, which highlights the important role of tuning the N doping patterns on enhancing the supercapacitive performances of carbon materials.