Unexpected Energy Applications of Ionic Liquids

Abstract Ionic liquids and their various analogues are without doubt the scientific sensation of the last few decades, paving the yellow brick road to a worldly version of Oz's green “Emerald city” – a more sustainable society. Their versatile suite of properties, originating from an almost inconceivably large number of possible cation and anion combinations, allows tuning of the structure to serve a desired purpose. Ionic liquids hence offer a myriad of useful applications from solvents to catalysts, through to lubricants, gas absorbers and azeotrope breakers. The purpose of this review is to explore the more unexpected of these applications, particularly in the energy space. It guides the reader through the application of ionic liquids and their analogues as i) phase change materials (PCMs) for thermal energy storage, ii) organic ionic plastic crystals (OIPCs), which have been studied as battery electrolytes and in gas separation, iii) key components in the nitrogen reduction reaction (NRR) for sustainable ammonia generation, iv) as electrolytes in aluminum ion batteries, and v) in other emerging technologies. We conclude that there is tremendous scope for further optimizing and tuning of the ionic liquid in its task, subject to sustainability imperatives in line with current global priorities, assisted by artificial intelligence. This article is protected by copyright. All rights reserved