N, O-codoped hierarchical porous carbons derived from algae for high-capacity supercapacitors and battery anodes

Nitrogen and oxygen codoped hierarchical porous carbons have been synthesized by using a direct carbonization/activation procedure of biomass algae - Enteromorpha. The proposed procedure allowed us to produce carbons with high surface area (up to 2073 m(2) g(-1)), sponge-like 3D interconnected structure, combined macro/meso/micropores, and rich N (0.64-0.85 at%) and O (11.36-12.24 at%) doping. The application of the produced carbons in supercapacitors based on an ionic liquid electrolyte showed a high specific capacitance of 201 F g(-1) (10.7 mF cm(-2)) at 1 A g(-1) and 20 degrees C, a capacitance retention ratio of 61% at 100 A g(-1) and a capacitance loss of 9% after 10 000 cycles. The devices were able to deliver an energy density of 24 or 35 W h kg(-1) (on an active mass normalized basis) at an extremely high power density of 60 kW kg(-1) at 20 or 60 degrees C. The application of the produced carbons in a lithium-ion battery anode based on the LiPF6 electrolyte exhibited a high specific capacity of 13471709 mA h g(-1), a good initial coulombic efficiency of 61-64%, and a good cyclability up to 500 cycles. We believe that this simple precursor-synthesis route offers excellent potential for facile large-scale material production for supercapacitors and lithium ion batteries.