A versatile Co-Activation strategy towards porous carbon nanosheets for high performance ionic liquid based supercapacitor applications

Two-dimensional (2D) nanocarbons have attracted considerable researching interest in electrochemical energy storage owing to their large surface area and shortened ion-diffusion distance. Herein, we propose a versatile co-activation strategy for preparing porous carbon nanosheets by employing easily available petroleum asphalt as the precursor. Besides KOH, introducing of NaOH as the co-activating reagent not only realized the morphological change from microparticles to nanosheets , but also altered the textural properties of the products, which is totally different from the traditional template route, offers a new possibility towards 2D nanocarbons. The large specific surface area and highly-developed micropores combined with its unique structural advantages, make it a very promising electrode material for high-rate supercapacitor in ionic liquid electrolyte. For instance, the porous carbon nanosheets deliver a large specific capacitance (169 F/g 1 A/g), superior rate capability (72.8% capacitance retention at 50 A/g), and good cycling stability after 5000 cycles. Moreover, the energy density can reach to 52.3 Wh/kg even at an ultrahigh power density of 43.75 kW/kg, which have shown great potential for applications in electrochemical energy storage devices such as supercapacitors.