Functional Electro-materials Based on Ferricyanide Redox-active Ionic Liquids

Abstract

The unique physical and chemical properties of conventional room temperature ionic liquids (RTILs) render them highly deployable materials in electrochemical devices performing functions such as solvent-free electrolytes in capacitors, batteries and sensors. However, these non-faradaic applications can be complimented by incorporating faradaic redox functionality into the ionic liquid structure which facilitates access to a large array of new electrochemical applications such as dye sensitised solar cells, redox batteries, hydrid capacitors and selective amperometric sensor applications which are all reliant on heterogeneous or homogenous electron-transfer processes. This paper presents and discuses some examples of redox active ionic liquids base on the ferri-/ferro- functionality. These functional electro-materials which are already known [Ref. [18]] exhibit simple reversible one-electron electrochemistry at very negative potentials (by at least −1V relative to aqueous systems) in anhydrous media. Glass transition temperatures lower than −50°C were also observed along with an overall thermal stability up to at least 400°C under dry N2 atmosphere conditions. Opportunities and challenges for these types of electro-materials are discussed.