An unusual low-surface-area nitrogen doped carbon for ultrahigh gravimetric and volumetric capacitances

Abstract

The popular pursuit of a high interior surface area, although leading to increasing capacitance records for carbon-based supercapacitor electrode materials, also produces low volumetric capacitances. We herein reported a porous nitrogen doped carbon material with a relatively low specific surface area of 403 m² g⁻¹ and a total pore volume of only 0.29 cm³ g⁻¹, exhibiting a very high gravimetric capacitance of 400 F g⁻¹ and a volumetric capacitance of 507 F cm⁻³ in a three-electrode system. Simultaneously, the energy density reaches 26.1 W h kg⁻¹ at a power density of 200 W kg⁻¹, and maintains 7.44 W h kg⁻¹ at 5000 W kg⁻¹, in a symmetric two-electrode test conducted in 6 M KOH solution. The result implies a maximized utilization of the interior surface and the significant capacitance contribution resulted from each unit surface, for which a systematic investigation on the critical structural features has been given.