Integrated N-doped carbon electrodes with regional synergistic energy storage mechanisms for zinc-ion hybrid supercapacitors

Zinc ion hybrid supercapacitors (ZIHCs) are attracting more attention, but there are still few studies on their energy storage mechanism and integrated cathode materials to build hierarchically ordered nanoporous structures. In this work, to construct an integrated binderless electrode, terminal amine conjugated microporous polymer airgels (CMPAs) with different shapes (columnar, rod, and linear shapes) are effectively synthesised by Sonogashira-Hagihara coupling reaction. Subsequently, we use them as precursors to prepare N-doped carbon microporous aerogel materials (NC-CMPAs) composed of interconnected nanotube structures through pyrolysis and alkali activation steps. Density functional theory (DFT) calculations show that N-doped can provide active sites in NC-CMPAs, enhance electronic conduction and reduce the binding energy of Zn2+ and NC-CMPAs. By convenient one-step slicing, we respectively assembled supercapacitor and Zn-ion hybrid capacitor using sheeting NC-CMPAs as integrated electrode. The assembled zinc-ion hybrid supercapacitor (Zn//NC-CMPAs ZIHCs) exhibits a high energy density (157.47 Wh kg−1), supercapacitor-like power behavior (8020.90 W kg−1) and long-term lifespan (over 15,000 cycles). Through the analysis of electrochemical behavior, the regional synergistic storage mechanism belonging to Zn2+ and H+ in the range of 0.2–1.2 V and 1.2–1.8 V respectively was discovered for the first time.