Ionic liquids offer a unique suite of properties that make them important candidates for a number of energy related applications. Cation–anion combinations that exhibit low volatility coupled with high electrochemical and thermal stability, as well as ionic conductivity, create the possibility of designing ideal electrolytes for batteries, super-capacitors, actuators, dye sensitised solar cells and thermo-electrochemical cells. In the field of water splitting to produce hydrogen they have been used to synthesize some of the best performing water oxidation catalysts and some members of the protic ionic liquid family co-catalyse an unusual, very high energy efficiency water oxidation process. As fuel cell electrolytes, the high proton conductivity of some of the protic ionic liquid family offers the potential of fuel cells operating in the optimum temperature region above 100 °C. Beyond electrochemical applications, the low vapour pressure of these liquids, along with their ability to offer tuneable functionality, also makes them ideal as CO₂ absorbents for post-combustion CO₂ capture. Similarly, the tuneable phase properties of the many members of this large family of salts are also allowing the creation of phase-change thermal energy storage materials having melting points tuned to the application. This perspective article provides an overview of these developing energy related applications of ionic liquids and offers some thoughts on the emerging challenges and opportunities.

The stability of encapsulated planar-structured CH₃NH₃PbI₃ (MAPbI₃) perovskite solar cells (PSCs) was investigated under various simulated environmental conditions.

Ionic liquids have become an increasingly popular class of solvent in the last decade as the potential applications of these materials become more diverse. Rather than being viewed simply as replacement for conventional organic solvent media, research into ionic liquids has progressed to the deliberate choice and design of these materials for reasons of improved rate, specificity, and yield. Design of ionic liquids centres on the development of novel cations and anions to impart the specific physical properties required for each application. Therefore, the materials being synthesized and studied are also becoming increasingly complex and diverse. Here we provide an overview of ionic liquids generally, and some of their current applications, as well as an introduction to some of the new cations and anions that have been developed for specific properties.

As highlighted by the recent ChemComm web themed issue on ionic liquids, this field continues to develop beyond the concept of interesting new solvents for application in the greening of the chemical industry. Here some current research trends in the field will be discussed which show that ionic liquids research is still aimed squarely at solving major societal issues by taking advantage of new fundamental understanding of the nature of these salts in their low temperature liquid state. This article discusses current research trends in applications of ionic liquids to energy, materials, and medicines to provide some insight into the directions, motivations, challenges, and successes being achieved with ionic liquids today.