Ultrahigh voltage window, preeminent energy density aqueous supercapacitor derived from honeycomb-like porous carbon decorated with carbon dots

Abstract

The development of advanced electrode materials with high specific capacitance and wide voltage window is of great importance in improving the low energy density of aqueous supercapacitors (ASCs). Herein, a novel heteroatoms doped 3 D porous carbon decorated with 0 D carbon dots is prepared from egg whites and yolks. The unique honeycomb-like interconnected pore structure and multi-component feature endows the prepared material with specific surface area (1999.3 m2/g), high pore volume (1.22 cm3/g) with abundant micropores (0.67 cm3/g) and multi-doped heteroatoms including P, S, O and N, leading to excellent specific capacitance of 472.9 F/g at 1 A/g. More importantly, the symmetric supercapacitor assembled from the prepared porous carbon exhibits the voltage window as high as 2.6 V in 1.5 M Na2SO4 aqueous electrolyte. Hence, the symmetric supercapacitor achieves a leap forward in energy density (107.5 Wh/kg at a power density of 650 W/kg and maintains about 65.2 Wh/kg at 26,000 W/kg) relative to other ASCs. These preeminent results provide important insight for the design of aqueous symmetric carbon-based supercapacitor with ultrahigh voltage window and energy density.