Nitrogen-enriched hierarchical porous carbon with enhanced performance in supercapacitors and lithium–sulfur batteries?

RSC Advances Pub Date: 2015-08-28 DOI: 10.1039/C5RA16104E

Abstract

It is quite desirable but challenging to prepare highly active materials for various energy storage applications at low cost. Here, an efficient strategy to produce nitrogen-enriched hierarchical porous carbon (N-HPC) is reported by facile pyrolysis of magnesium citrate and subsequent NH3 treatment. As-prepared N-HPC presents a developed hierarchical micro- and trimodal meso-porosity with a high specific surface area of 1290 m2 g?1 and pore volume of 3.04 cm3 g?1. It also shows an abundant nitrogen doping of 3.6%. When used for electrochemical electrodes in supercapacitors and lithium–sulfur (Li–S) batteries, significantly enhanced performances have been obtained compared with commercially available activated carbon. In supercapacitor testing, the N-HPC electrode shows a specific capacitance of 101 F g?1 in a nonaqueous electrolyte. And the capacitance retains 67% even at a 200-fold charge/discharge rate. Moreover, its performance in Li–S batteries is more outstanding. It enables a very high sulfur loading (76.2% by weight) and the resulting N-HPC/S cathode shows high discharge capacities of 1153 mA h g?1sulfur (or 702 mA h g?1electrode) at 0.2C and 671 mA h g?1 even at 4C. And it still remains 600 mA h g?1 over 300 charge/discharge cycles at 1C with an average coulombic efficiency of 99.0%.

Graphical abstract: Nitrogen-enriched hierarchical porous carbon with enhanced performance in supercapacitors and lithium–sulfur batteries
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