Enabling new electrochemical methods with redox-active ionic liquids

Redox-active ionic liquids are obtained by tethering an electroactive center to either the cation, the anion, or both ions in an ionic liquid. While such phases were studied back in the 1990s for their particular electrochemical behavior, they are currently under increased scrutiny for applications in electrochemical systems. This contribution identifies the redox-active ionic liquids’ most important aspects to promote their development. This article provides a review of their features and offers several design guidelines. In addition, it offers an overview of the key properties which enhance their suitability as electrolytes in electrochemical systems, with particular attention paid to lithium-ion batteries and electrochromic devices.