doi:10.1038/nindia.2017.72 Published online 27 June 2017
Researchers have synthesized graphene-like carbon nanosheets from low-grade coal. The sheets can be used to make supercapacitors1, which are efficient energy-storing devices with potential for making batteries for electric cars.
Supercapacitors have excellent abilities to store and discharge energy. They are attractive for their high power density, short charging time, and long life cycle.
In search of cheap materials to make supercapacitors, scientists led by Binoy K. Saikia from the CSIR-North East Institute of Science & Technology, Jorhat, India, prepared the carbon nanosheet by treating sulfur-containing low-grade coal with acids, then cooling and drying it.
Electrochemical studies on the supercapacitors made with the resultant nanosheet revealed a high scan rate, indicating the formation of double-layer capacitor which can efficiently charge and discharge. The supercapacitors retained their efficiency even after 1000 cycles of charging and discharging.
The presence of oxygen-containing functional groups and sulfur in the nanosheet possibly enhanced access and utilization of its pores, resulting in uniform fast charge-discharge cycles. The low-cost and eco-friendly way to make the coal-derived carbon nanosheet is a promising electrode material, the researchers say.
1. Das, T. et al. Promising carbon nanosheet-based supercapacitor electrode materials from low-grade coals. Micro. Meso. Mater.(2017) doi: 10.1016/j.micromeso.2017.06.030