Pyrrolic-N/C = O cooperative assisted in hollow porous carbon with ultra-high electrochemical performance for Zn-ion hybrid supercapacitors

Abstract

The development of high-energy–density advanced Zinc-ion hybrid supercapacitors (ZIHSs) shows significant potential, yet it remains a complex undertaking due to its heavy reliance on physical Zn2+ adsorption and the limitations imposed by insufficient cathodes. This study employs a rich in C = O and pyrrolic-N functional groups hollow porous carbon derived from cattail leaves as a cathode material for high-energy-power ZIHSs. The proposed charge storage mechanism involves the assimilation of opposite charge carriers, coupled with a multi-electron redox response, which was investigated by Ex-situ experiments and density functional theory (DFT) simulations. This process entails the alternating binding of Zn2+ and SO42− at designated active sites, along with strong relationships between Zn2+ and electronegative C = O/pyrrolic-N motifs, leading to the creation of C-O-Zn-N-C bonds. Consequently, the aqueous ZIHSs constructed with this hollow porous carbon cathode exhibit outstanding performance metrics. These include an impressive energy density of 128 Wh kg−1, a discharge specific capacity of 149 mAh/g at 10 A/g, a superb power density of 1188 W kg−1, and an extraordinary long-term lifespan, retaining 95 % of its initial capacity after 10,000 cycles. Importantly, the strategy of augmenting energy storage through chemical adsorption capability modulation can be applied to other carbon materials.