Enhancement of a Green Supercapacitor With a Hydrogel/Carbon Nanotubes-Based Electrolyte

The purpose of this work is to suggest the conception of a supercapacitor using environment-friendly materials, in addition to exhibiting good electrochemical performances. In order to lower the environmental footprint of supercapacitors, one current attempt in the literature is to replace efficient but toxic organic electrolytes by harmless, bio-friendly electrolytes such as a mixture of sodium salt with a hydrogel. However, those bio-friendly electrolytes have not been demonstrated yet to be a relevant alternative, as they are still not able of similar performances as toxic organic electrolytes. The work reported in this paper demonstrates, as a different approach, that the capacitance of a bio-friendly, hydrogel-based electrolyte combined with sodium salt can be significantly increased by adding carbon nanotubes (CNTs) to the gel. As a result, the supercapacitor using the CNT-loaded bio-friendly electrolyte has registered not only an enhanced capacitance, but also better energy and power densities compared to both the same but CNT-free electrolyte, and a toxic DMSO-based organic electrolyte.