Design of Co–Al–Mn LDH@Ti₂CT_x Asymmetric Supercapacitor: A Comprehensive Study on the Role of Redox Electrolyte and Its Application in Flexible Electronics

Abstract

The unrivaled depth of the energy crisis has imposed a critical challenge to appraise the existing innovations in energy storage devices. Supercapacitors lag behind in terms of energy density, on par with batteries, which has led to the development of hybrid capacitors exhibiting improved energy density. Despite possessing good physiochemical properties proportionate to Ti 3 C 2 T x MXene, Ti 2 CT x has been less explored. In this study, we exploited the theoretical aspects of Ti 2 CT x to elucidate its potential as a promising supercapacitor device. Further, to improve the performance and stability of Ti 2 CT x , we have coupled it with a Co−Al−Mn layered double hydroxide (LDH) via a facile ultrasonication approach. The electrochemical parameters of Co−Al−Mn LDH@Ti 2 CT x were assessed in a redox additive electrolyte, viz., potassium hydroxide and potassium ferricyanide (6 M KOH + 0.01 M K 3 [Fe(CN) 6 ]). The addition of Fe(CN) 6 3− ameliorates the performance due to the arousal of the redox couple during the charging and discharging of the supercapacitor device. A redox mechanism has been proposed to highlight the improvement of the performance when a redox additive is used. The Co− Al−Mn LDH@Ti 2 CT x electrode displays a specific capacitance value of 221 F/g at 5 mVs −1 . A solid-state flexible device was constructed with a PVA/KOH gel electrolyte, which exhibited good stability despite twisting the electrode at various bending angles. To elucidate the practicability of the constructed device, a red LED light was illuminated using three electrodes arranged in series.