Extremely safe, high-rate and ultralong-life zinc-ion hybrid supercapacitors

With rapid development of portable electronics and electric vehicles, high-performance energy storage devices are urgently needed; however, the existing energy storage systems often have some deficiency, such as low energy for supercapacitors, security risks for lithium-ion batteries and poor cycling stability for alkaline zinc/manganese dioxide batteries. Here we report a novel energy storage system of zinc-ion hybrid supercapacitors (ZHSs), in which activated carbon materials, Zn metal and ZnSO4 aqueous solution serve as cathode, anode and electrolyte, respectively. Reversible ion adsorption/desorption on AC cathode and Zn2+ deposition/stripping on Zn anode enable the ZHSs to repeatedly and rapidly store/deliver electrical energy, accompanying with a capacity of 121 mAh g−1 (corresponding to an energy of 84 Wh kg−1), a very large power output of 14.9 kW kg−1 and an excellent cycling stability with 91% capacity retention over 10000 cycles. The extremely safe, high-rate and ultralong-life ZHSs are believed to provide new options for next-generation energy storage devices.