Biomass-derived nitrogen/oxygen co-doped hierarchical porous carbon with a large specific surface area for ultrafast and long-life sodium-ion batteries

Biomass derived porous carbons are economic and attractive materials for anode electrodes in sodium- ion batteries. In this work, a novel porous carbon has been prepared through activation of longan shell, which demonstrates an interconnected hierarchical porosity comprised of macro-, meso- and micro- pores as well with a high specific surface area of 2990 m(2) g(-1). Benefiting from the unique pore structure and oxygen and nitrogen dual doping, a well-developed ionic and electronic conductivity is achieved. Remarkably, it exhibits an excellent cycling stability with a capacity up to 345.9 mAh g(-1) at a current density of 0.1 A g(-1), and maintains a capacity of 304.2 mAh g(-1) even at a high current density of 5 A g(-1) after 1000 cycles as anodes for sodium-ion batteries. These results indicate that the fabricated porous carbon could be a promising electrode material for sodium- ion batteries. The mechanism of such high sodium-ion storage was also discussed with the scan- rate- dependent CV curves to quantify the pseudo-capacitive contribution.