Critical evaluation of reference systems for voltammetric measurements in ionic liquids

The study of ionic liquids in electrochemistry is currently a highly active area of research. Examples are the use of ionic liquids in the development of energy storage devices, in electrodeposition, and electroanalytical studies, both in academia and for industrial applications. However, very little information and understanding is available regarding the effect of poorly chosen reference electrodes on reported electrochemical data. In this review, the latest understanding and practical approaches to the application of reference electrodes and internal reference redox couples in ionic liquids are featured and critically discussed. Problems observed during the application of these systems are discussed based on experimental examples. Implications of non-additivity of Faradaic current in the use of internal reference scales in ionic liquids are also presented.