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(2) g(−1)), large total pore volume (up to 1.374 cm(3) g(−1)), 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(−1) at 0.5 A g(−1) with a capacitance retention ratio as high as 67.5% at 100 A g(−1), 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(−1) at a specific power of 372 W kg(−1), and maintains 21 W h kg(−1) at the high power of 40 kW kg(−1). Moreover, the resultant carbon as a Li-ion battery anode delivers a high reversible capacity of 1262 mA h g(−1) at 0.1 A g(−1) and 730 mA h g(−1) at 0.5 A g(−1), and maintains a high capacity of 439 mA h g(−1) after 500 cycles at 1 A g(−1). These results demonstrate that the nettle leaf derived porous carbons offer great potential as electrodes for advanced supercapacitors and lithium ion batteries.