Preparation of High-Performance Hierarchical Porous Activated Carbon via a Multistep Physical Activation Method for Supercapacitors

Biomass-derived activated carbons (ACs) areregarded as important electrode materials for supercapacitors(SCs) due to their abundance and large specific surface areas(SSAs). Here, we develop a multistep physical activation strategyby combining water vapor and CO2activation to prepare apricotshell-derived activated carbons (ASACs). Compared to thetraditional single physical activation method, such a multistepactivation strategy is conducive to forming an excellent hierarchicalporous structure. The as-obtained ACVC-4 displays a high SSA andpore volume, and its effective pore volume and the mesoporousvolume fraction are 0.720 cm3g-1and 55.76%, respectively.Furthermore, the ACVC-4 has a superior specific capacitance of39.17 F g-1at 0.5 A g-1as the electrode material in the 1-ethyl-3-methylimidazolium tetrafluoroborate electrolyte for SCs. When the current density increases from 0.5 to 10 A g-1, its capacitanceretention rate reaches 87.77%, which is far higher than that of other ASACs and commercial YP-50F. We believe that the multistepactivation strategy for preparing ACs could open a new way to obtain high-performance electrode materials for SCs