Highly stable Megalopolis lignite based N and S self-doped hierarchically porous activated carbons for high performance supercapacitors and ash content effects on performance

This study proposes that high value-added activated carbon (AC) is produced from lignite (low rank coal) and used as electrode material in supercapacitors. In addition, the effects of the ash content of the activated carbon on supercapacitor performance are determined. The ACs at a temperature of 800 degrees C are produced in three different impregnation ratios (IR) (IR: 1, 2 and 4: KOH/precursor) using KOH as the activation agent. While the surface area of the AC produced at IR4 is 2531.4 m(2) g(-1), it is determined as 1321.3 (IR1) and 1989.0 (IR2) m(2) g(-1) for the others. The pore size analysis of the samples shows that the mesopores are dominant in the IR1 (52.73%) and IR4 (88.74%) samples, while it is observed that the micropores are dominant in the IR2 (69.03%) sample. The IR4 sample gives excellent results. The cell specific capacitances of this sample are determined as 260.47 F g(-1) (at 1 A g(-1)) and 150.3 F g(-1) (at 50 A g(-1)). The amount of ash in the AC samples dramatically reduces the supercapacitor performances and significantly increases the resistances.

Automated summary

This study explores the production of high value-added activated carbon from lignite for supercapacitor applications, and investigates the effect of ash content on supercapacitor performance. The results show that the ash content in activated carbon samples significantly reduces supercapacitor performance and increases resistances.