Azure A Anchored on N-Doped Porous Carbon for Zinc-Ion Hybrid Supercapacitors with Boosting Energy Density

The cathode materials of zinc-ion hybrid supercapacitors (ZIHSCs) have a significant impact on their electrochemical performance. Thus, modification of the carbon cathode is an important strategy in this field. In this work, azure A (AA) and urea were selected as active molecules and dopants to modify active carbon (TAC, prepared by using tea leaves) for high-performance ZIHSCs through a one-step hydrothermal method. The capacity of the hybrid capacitor rises from 153.4 to 257.6 mAh g–1 at 0.2 A g–1 due to the pseudocapacitance of the highly active AA molecules. Furthermore, by the large amount of N and O functional groups, N doping not only enhances the anchoring effect of TAC to AA but also increases the ZIHSC’s capacity from 257.6 to 335.5 mAh g–1 at 0.2 A g–1. Therefore, the ZIHSC assembled by an AA/NTAC-0.5 cathode delivers the maximum energy density of 301.9 Wh kg–1 with a power density of 180.0 W kg–1. The capacitance retention with 103.8% after 65,000 charge/discharge cycles demonstrates that the synergistic effect of AA and N doping promotes the practical application of ZIHSCs.