Dual-doped hierarchical porous carbon derived from biomass for advanced supercapacitors and lithium ion batteries.

Nowadays, designing heteroatom-doped porous carbons from inexpensive biomass raw materials is a very attractive topic. Herein, we propose a simple approach to prepare heteroatom-doped porous carbons by using nettle leaves as the precursor and KOH as the activating agent. The nettle leaf derived porous carbons possess high specific surface area (up to 1951 m g), large total pore volume (up to 1.374 cm g), and high content of nitrogen and oxygen heteroatom doping (up to 17.85 at% combined). The obtained carbon as an electrode for symmetric supercapacitors with an ionic liquid electrolyte can offer a superior specific capacitance of 163 F g at 0.5 A g with a capacitance retention ratio as high as 67.5% at 100 A g, and a low capacitance loss of 8% after 10 000 cycles. Besides, the as-built supercapacitor demonstrates a high specific energy of 50 W h kg at a specific power of 372 W kg, and maintains 21 W h kg at the high power of 40 kW kg. Moreover, the resultant carbon as a Li-ion battery anode delivers a high reversible capacity of 1262 mA h g at 0.1 A g and 730 mA h g at 0.5 A g, and maintains a high capacity of 439 mA h g after 500 cycles at 1 A g. These results demonstrate that the nettle leaf derived porous carbons offer great potential as electrodes for advanced supercapacitors and lithium ion batteries.