Hierarchical porous carbon prepared by NaOH activation of nano-CaCO3 templated carbon for high rate supercapacitors

Abstract

Hierarchical porous carbon is prepared from sucrose by the nano-CaCO₃ template method followed by NaOH activation for supercapacitors. As evidenced by SEM, TEM, nitrogen sorption and Hg porosimetry analysis, the carbon possesses a highly developed hierarchical porous texture containing interconnected micro-, meso-, and macropores. The surface area and pore volume of the carbon reach up to 2032 m² g⁻¹ and 2.602 cm³ g⁻¹, respectively. Galvanostatic charge–discharge and cyclic voltammetry measurements indicate that the carbon shows high capacitance and excellent rate capability in both aqueous and non-aqueous electrolytes, which are attributed to its unique hierarchical porosity. In the 6 mol L⁻¹ KOH aqueous electrolyte, it can afford a capacitance of 245 F g⁻¹ at 0.05 A g⁻¹, which remains at 188 F g⁻¹ as the current density increases up to 50 A g⁻¹, while the value reaches 144 F g⁻¹ at 0.05 A g⁻¹ and remains at 103 F g⁻¹ at 10 A g⁻¹ in the 1 mol L⁻¹ Et₄NBF₄/PC non-aqueous electrolyte.