Highly porous nitrogen-doped carbon for superior electric double-layer capacitors

Abstract

In recent years, the research of doping heteroatoms in a carbon framework for supercapacitive electrodes has drawn tremendous attention due to the highly active electrochemical performance characteristics of the resulting materials. Here, we present a method to synthesize highly porous nitrogen-doped carbon nanomaterials derived from a polyvinylpyrrolidone (PVP) material via a relatively low-temperature simultaneous activation/calcination process. PVP fine powder was mixed with sodium hydroxide as a carbon-activation agent and calcined at a relatively low temperature of 600 °C for one hour under a nitrogen atmosphere. By this process, we obtained a highly porous nitrogen-doped carbon material, possessing a specific surface area of 2400 m² g⁻¹, which was formed with an amorphous and graphitic structure incorporating ultrathin large sheets. The resultant material displays an excellent specific capacitance (478 F g⁻¹ at 1 A g⁻¹) and a high retention rate of 99.6% after 10 000 cycles at 10 A g⁻¹. The symmetric supercapacitor exhibits high energy densities of 14.2 W h kg⁻¹ and 5.7 W h kg⁻¹ at power densities of 720 W kg⁻¹ and 6035 W kg⁻¹, respectively.