N, O co-doped hierarchically porous carbon derived from pitch/g-C3N4 composite for high-performance zinc-ion hybrid supercapacitors

Abstract

Aqueous zinc-ion hybrid supercapacitors (ZIHSCs) are highly favored for their abundant raw resources, friendly environment, high safety and unique electrochemical advantages. Nevertheless, their practical application is severely limited by the unsatisfactory zinc ion storage capacity of cathode materials. Herein, we constructed a N, O-enriched hierarchically porous carbon composed of ultrathin carbon nanosheets for ZIHSC cathode materials. Benefiting from the synergistic merits of unique structure, large specific surface area, abundant micro/mesopores, and high N and O content, the porous carbon electrodes demonstrate a substantial capacity of 287.2 mAh·g-1 at 0.05 A·g-1, accompanied by a maximal energy density of 86.5 Wh·kg-1. Moreover, the assembled ZIHSCs present superior high-rate performance and impressive durability with capacity retention of 79.75% over 25,000 charge/discharge cycles. This strategy proposes a scalable approach to enhance the electrochemical energy storage capacity of ZIHSCs by coupling rapid ion adsorption and reversible redox reactions, which offers a new option for constructing low-cost cathode materials for desirable ZIHSCs.