Hydrogel and carbon nanostructures based supercapacitor: Initial steps toward green supercapatteries

Efficient distribution and storage of energy are crucial to mitigate the effects of climate crisis; fortunately, scientific community is making accelerated actions to improve and create prototypes allowing a sustainable use of energy. In particular, we will center our discussion on results showing the enhancement of energy and power densities of a supercapacitor that allows rapid energy delivery working with a nontoxic electrolyte. The use of nanostructures (carbon nanotubes and graphene) allows to increase the supercapacitor capacitance, by inherently increasing surface area, with an important impact on energy power density. The broadening of the electrochemical window of the hydrogel based electrolyte also has a positive influence on power density. Herein is depicted a green prototype with good power density (1779.41 W kg−1), typical of supercapacitors, but also with good energy density (105.37 W h kg−1), with a cycling life (2000 cycles) superior of some hydrogel electrolyte based supercapacitors, but still far from an efficient system. Those results have to be improved, but are promissory to combine the best characteristics of supercapacitors and rechargeable batteries, into a green supercapattery.