A robust 2D porous carbon nanoflake cathode for high energy-power density Zn-ion hybrid supercapacitor applications

[Display omitted] •Porous carbon nanoflakes have been synthesized via mild one-step KHCO3 activation process.•KHCO3 induced etching process can transform nanocage into nanoflakes.•The obtained products displayed large specific surface area and tunable mesopore content.•Porous carbon nanoflakes can be used as the cathodes for Zn-ion hybrid supercapacitor.•The product with suitable mesopore content displays excellent electrochemical performance. The exploration of next-generation energy storage devices with long cycle life, superior stability, large specific capacity, ultrahigh power and energy density have attracted increased interests in recent years. However, it still remains a tremendous challenge for conventional energy storage devices to achieve the merits of both batteries and supercapacitors. Herein, we present a convenient but effective approach to synthesize porous carbon nanoflakes (PCNFs) that process high specific surface area and tunable pore size distributions. We found the amount of activating reagent has a profound influence on the morphology and textural structure of the resulting products, and a chemical etching process to transform nanocages into nanoflakes has been proposed. Importantly, Zn-ion hybrid supercapacitor with PCNFs as cathode and Zn foil as anode can overcome the disadvantages of poor rate capability and low energy density for the conventional batteries and supercapacitors. The optimized PCNFs based Zn-ion hybrid supercapacitor can deliver an ultrahigh specific capacitance, excellent rate performance, outstanding cycling stability, and impressive energy density. The facile synthetic procedure combined with its excellent electrochemical performances endow the present devices a huge possibility to be used in future electrochemical energy storage systems.