High-performance Zn-ion hybrid supercapacitor enabled by the hierarchical N/S co-doped graphene/polyaniline cathode

Zinc ion hybrid supercapacitors (Zn-HSCs), combined with the superiorities of supercapacitors and batteries, are regarded to have evolutive potential in devices of energy storage. Herein, the nitrogen and sulfur co-doped graphene/polyaniline nanoarrays (NSG/PANI) have been successfully compounded by in-situ polymerization. The structural characterization shows that the NSG/PANI-50 nanocomposite possess more active sites and vertically arranged PANI nanoarrays on the surface of NSG. The Zn-HSCs devices assembled by the zinc foil as anode, NSG/PANI-x (x = 30, 50, 70) as cathode and ZnSO4 as electrolyte (NSG/PANI//ZnSO4 (aq.)//Zn) show extraordinary energy storage properties. The prepared NSG/PANI-50//Zn device exhibits exceptional specific capacitance of 268.4 F g−1 at 0.1 A g−1 (the retention rate is 75.2% as the current density increased 20-times from 0.1 A g−1 to 2 A g−1), high energy density (95.4 Wh kg−1) and excellent capacitance retention rate of ~ 93% at 5 A g−1 after 10,000 cycles. The diffusion-controlled behavior (72% of the total storage charge at 5 mV s−1) suggests that the diffusion-controlled process acts a momentous role in the process of energy storage. The impressive results demonstrate that NSG/PANI nanocomposite could be a potential high-performance electrode material for Zn-ion hybrid energy systems.