Supramolecular nanofibers as ambient stable wide voltage window electrolyte for micro-supercapacitors

Abstract

In this paper, we explore the use of supramolecular nanofibers as an electrolyte for in-plane micro-supercapacitors. The supramolecular nanofibers obtained from the self-assembly of donor-acceptor (D-A) molecules, coronene tetracarboxylate salt (CS) and dodecyl methyl viologen (DMV), carrying positive and negative ionic charges, respectively, were drop-coated onto metal gap electrodes using an aqueous dispersion to form the device. Under dry conditions (<35% relative humidity, RH), the device exhibited a stack capacitance of 160 Fcm-3 with energy and power densities comparable to high-performance micro-supercapacitors. Although the electrolyte has aqueous origin, in dry conditions, it is capable of operating in a voltage window of 0-3 V. This supramolecular micro-supercapacitor device (micro-SS) was fabricated only with metal electrodes without using electrode material in it, thanks to the ability of the nanofiber to provide extended surface area for charge storage. The 1D face-to-face arrangement of D-A molecules seems to provide an efficient pathway for the diffusion of ions across the electrodes. The present study not only provides a new approach to obtain an ambient stable electrolyte with wide operating voltage window but also gives a low-cost method of fabricating micro-supercapacitors with reasonably high energy and power densities.