Energy applications of ionic liquids

Abstract

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 thermoelectrochemical 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 CO 2 absorbents for post-combustion CO 2 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.

Room temperature ionic liquid electrolytes for redox flow batteries

“…A possible solution is to use an RTIL as solvent; due to their thermal and electrochemical stability, low vapour pressures, and wide potential windows, RTILs are being used in electrochemical devices such as batteries, supercapacitors, and fuel cells but relatively few studies have explored their use in RFBs [9][10][11]. A couple of studies involved using RTILs as supporting electrolytes in non-aqueous, all- Oxidation and reduction peaks associated with the Fe 2+/3+ redox couple were observed and the reaction was electrochemically quasi-reversible.…”

Design and Materialization of Ionic Liquids Based on an Understanding of Their Fundamental Properties

“…7 In the initial stages of our studies in this area, two approaches were chosen. One is the synthesis of lithium ILs, 78,79 and the second is the addition of suitable lithium salts to aprotic ILs.…”

“…[1][2][3][4][5][6][7] They are readily available and possess unique properties such as non-volatility, high thermal stability, and designability, making ILs designed for specific tasks or for use under unusual conditions possible. [1][2][3][4][5][6][7] Our studies on ILs have focused on understanding their unique properties. Furthermore, we have investigated their uses as neoteric solvents and electrolytes for the new materials and devices necessary for a future sustainable society.…”

Hydrogen Electrooxidation under Conditions of High Mass Transport in Room-Temperature Ionic Liquids and the Role of Underpotential-Deposited Hydrogen

“…28 Due to their unique properties, such as wide electrochemical windows, inherent conductivities, and thermal stabilities, the electrochemical applications of RTILs have increased significantly in recent years and include fundamental studies of mass-and charge-transfer dynamics, 29 and uses as electrolytes in devices such as fuel cells, batteries and supercapacitors. 30 Fundamental studies of electrocatalytic reactions in RTILs have also increased in number and include studies of the HOR. [30][31][32] For example, Compton has used aprotic ionic liquids (i.e., those with aprotic organic cations) to reveal new insights into the roles of RTIL ions during the HOR (and HER)…”

“…30 Fundamental studies of electrocatalytic reactions in RTILs have also increased in number and include studies of the HOR. [30][31][32] For example, Compton has used aprotic ionic liquids (i.e., those with aprotic organic cations) to reveal new insights into the roles of RTIL ions during the HOR (and HER)…”