Enhanced energy storage of aqueous zinc-carbon hybrid supercapacitors via employing alkaline medium and B, N dual doped carbon cathode.

Zinc-based energy storage systems (zinc-air, zinc-nickel and zinc-ion batteries and zinc-ion hybrid supercapacitors (ZHSs) are considered as promising power sources for wide applications from personal electronic devices to electric vehicles. However, these systems, especially the Zn-based hybrid supercapacitors, display unsatisfying power density and energy density, which should be enhanced for their large-scale applications. In this work, aqueous alkaline zinc-carbon hybrid supercapacitors (A-ZCHS) were designed, consisting of B, N dual doped carbon cathode, Zn anode and KOH electrolyte. The B, N dual doped carbon was prepared via thermal treatment of metal-organic frameworks and boric acid, which exhibits abundant hierarchical pore structure (micropore, mesopore and macropore) and suitable defect construction, promoting ion diffusion/charge transfer and providing more rapid surface pseudocapacitance reaction. More obviously, when the optimized B, N dual doped carbon was used as cathode in A-ZCHS and ZHS, more capacitive charge storage and rapider electrochemical kinetics can be observed in A-ZCHS than in ZHS. Therefore, the optimized A-ZCHS displays a high energy density of 115.7 Wh kg at the power density of 711.6 W kg with excellent stability, which is much better than most of ZHSs reported previously. The A-ZCHS should be a promising candidate for energy storage applications.