Metal-organic frameworks derived porous carbon nanosheets with boosted specific surface area and ultrahigh N doping degree for high-performance Zn-ion hybrid supercapacitors

Herein, by using ZIF-8, a metal–organic frameworks (MOFs) material, as nitrogen and carbon sources, KOH as activator and LiCl/KCl as medium, a new variety of N-doped porous carbon nanosheets is developed via an affordable molten salt assisted pyrolysis route. Results verify that, with KOH activation, pore volume and specific surface area of the flake-like specimen are obviously enriched, which contribute to a hierarchically porous structure. Specifically, ZNPCN-0.2–750 with total pore volume of 1.0 cm3 g−1, specific surface area of 787.6 m2 g−1 and high N-doping content of 21.2 at% exhibits a decent capacitive property as cathode for Zn-ion hybrid supercapacitors (ZHSs), such as energy density of 83.2 Wh kg−1 at 399.9 W kg−1, specific capacitance of 233.9F/g at 0.5 A g−1 and cyclic stability with capacitance retention of 87.7 % after 20,000 cycles. These performance parameters exceed numerous ZHSs reported so far, guaranteeing a huge potential in practical application.