Eco-Friendly EOG/PEDOT: PSS-Based Nanocomposites Blended with Green Additives for Flexible Supercapacitor Application

Flexible supercapacitors, often referred to as ultracapacitors, have emerged as a highly promising solution for addressing the increasing power requirements of modern energy-storage technologies, particularly in portable electronics and automotive battery systems. In this scenario, this study aims to develop eco-friendly ternary nanocomposites to produce electrodes for supercapacitors, based on poly(3,4-ethylene-dioxythiophene): polystyrenesulfonate (PEDOT: PSS), doped with Edge Oxidized Graphite (EOG) and green additives (glucose (G) and ascorbic acid (AA)). EOG is synthesized through sustainable oxidation with hydrogen peroxide (H2O2) and exhibits oxygenated functionalities located along the sheet edges, enabling effective interaction with the polymer matrix. G-EOG/PEDOT: PSS and AA-EOG/PEDOT: PSS nanocomposite dispersions were developed and analyzed from a chemical and rheological perspective. The pseudoplastic (shear-thinning) behavior of the PEDOT: PSS ink is preserved even after the inclusion of EOG and the dispersing agents, with a slight increase in viscosity observed at a low shear rate, ranging from 1.45 to 1.84 and 2.04 Pa·s. This can be attributed to the formation of a network and the increased hydrodynamic volume imparted by the EOG sheets, as well as their interaction with the dispersing agents’ functionalities. Subsequent morphological characterization (SEM and AFM) revealed that the addition of both green additives improves the dispersion of EOG within the PEDOT: PSS, resulting in a smoother and more homogeneous surface. Thermogravimetric analysis indicates that the presence of EOG contributes to a higher residual mass due to its intrinsic thermal stability and a moderate shift in the polymer degradation pathway. Electrochemical measurements (CV, EIS, LSV, and GCD) demonstrate that the AA-EOG/PEDOT: PSS nanocomposite provides the most significant performance improvement, displaying higher specific capacitance (4.75% increment), 94.6% capacitance retention, lower charge-transfer resistance, more capacitive (near-vertical) low-frequency response, and extended discharge durations than both pristine PEDOT: PSS and the G-EOG/PEDOT: PSS nanocomposite. Overall, this advancement highlights the promising capabilities of these nanocomposites in developing electrodes for flexible supercapacitors.