Development of a Novel Bio-based Redox Electrolyte using Pivalic Acid and Ascorbic Acid for the Activated Carbon-based Supercapacitor Fabrication

Supercapacitor is considered a promising energy storage device due to its high-power density and high specific capacitance. Electrode materials and electrolytes are major components of supercapacitors. The most used electrolytes are not biocompatible, which limits their practical applications. Bio-electrolytes often cause low performances of supercapacitors. However, the inadequate performances of bio-electrolytes for supercapacitor applications could be improved using redox molecules. Here, we are reporting the development of a novel redox bio-electrolyte based on pivalic acid (PA) and ascorbic acid (AA). The salts of PA and AA served as the bio-electrolyte and redox molecules, respectively. It is worth to note that PA which can be generated from bio-sources and industrial wastes, is soluble in alkaline solutions. AA is found in most living organisms, including plants. The developed supercapacitor with the bio-based redox electrolyte provides a specific capacitance of 308 Fg⁻¹ at a current density of 1 Ag⁻¹ and achieved an energy density of 15 Whkg⁻¹ at a power density of 300 Wkg⁻¹. The supercapacitor demonstrates a good coulombic efficiency of ∼97% with capacitance retention of ∼72% after 10000 charge-discharge cycles. This study is expected to widen the applications of bio-based redox electrolytes for practical electrochemical energy storage applications and enables access to greener and more sustainable energy storage technology.