Physicists have converted waste cotton into highly porous carbon fibres that have been used to make carbon electrodes1. These electrodes are potentially useful for making supercapacitors that, when combined with solar cells, can power light-emitting diodes (LED).
Supercapacitors possess excellent abilities to store charge and discharge. However, they are usually made using expensive materials and highly inflammable electrolytes, hence limiting their widespread application.
In search of a cheap material and safe electrolytes for making affordable supercapacitors, scientists from the International Advanced Research Centre for Powder Metallurgy and New Materials in Hyderabad, India, synthesised highly porous carbon fibres from waste cotton and then converted these fibres into carbon electrodes.
The researchers then made prototype supercapacitor cells using the electrodes and specific electrolytes. When connected in a series, a set of supercapacitor cells generated voltage that lit up 40 LED lights. Connecting the same set of cells in parallel illuminated a high-power LED light.
The cells, when combined with commercial solar cells, were able to power a commercial solar lantern with 40 LED lights, suggesting these cells’ potential to store electrical energy generated from sunlight.
Since the supercapacitor cells can store charge and discharge when needed, they can power solar lanterns even in the absence of sunlight. The cells retained their original capacitance with minimal loss in efficiency even after 1000 and 2000 cycles of charging and discharging, thus indicating the efficiency and stability of the cells.