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 (0.640.85 at%) and O (11.3612.24 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 F cm 2 ) at 1 A g 1 and 20 C, a capacitance retention ratio of 61% at 100 A g 1 and a capacitance loss of 9% after 10000 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 C. The application of the produced carbons in a lithium-ion battery anode based on the LiPF 6 electrolyte exhibited a high specific capacity of 13471709 mA h g 1 , a good initial coulombic efficiency of 6164%, 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. Nitrogen and oxygen codoped hierarchical porous carbons have been synthesized by using a direct carbonization/activation procedure of biomass algae Enteromorpha.