Enhanced electrochemical performance and high voltage window for supercapacitors based on fabric electrodes derived from tannin-Fe3+ complexes

Abstract

The acquisition of high energy density for aqueous supercapacitors (SCs) is effective in extending the operating voltage and increasing the capacitance, which has drawn a great deal of attention in recent years. A scalable approach has been proposed by dip coating and carbonizing tannin-Fe3+ (TA-Fe3+) coordination compounds to prepare fabric electrodes, which can provide tannin carbon (TC) and Fe3O4 for extended voltage windows and high specific capacitances, respectively. A fabric electrode with a chemically stable carbon core-shell structure was shown to improve its decomposition overpotential of water, which contributed to a wide operating voltage of 2.4 V for aqueous symmetric supercapacitors (SSCs). The assembled all solid-state SSCs achieved both an ultrahigh energy density of 51.26 μWh cm−2, which was higher than most SSCs and even some asymmetric SCs, and the ability to connect them in series to function as practical energy storage devices. This work opens up the possibility for high operating voltage aqueous SCs and even more possibilities for SCs.