Preparation of porous carbon by physical-chemical activation for high-performance supercapacitors

Abstract

High weight capacity of activated carbon often requires high specific surface area and developed pore volume, which resulting in low volumetric specific capacity. In this paper, a combined physical-chemical activation method is proposed to construct a hierarchical pore structure with appropriate distribution of micropores/mesopores. Micropores provide numerous sites for ion adsorption, while mesopores serve as channels for rapid ion transport. Based on this structure, the resulting sample AC30 achieve a high volumetric specific capacitance (335 Fꞏcm -3 at 0.5 Aꞏg -1 ) in 6 M KOH electrolyte. The assembled capacitor could reach a capacitance retention of 94% after 25000 cycles at 10 Aꞏg -1 . The outstanding volumetric specific capacity is attributed to the rational distribution of mesopores and micropores, which also provides guidance for the pore design of carbon materials.