Describing the unsuspected advantage of redox ionic liquids applied to electrochemical energy storage
Charlotte Bodin, Bruno Gélinas, Jie Deng, Kulika Pithaksinsakul, Yachao Zhu, Dominic Rochefort, Olivier Fontaine
Abstract
Ionic liquids are a class of solvents widely studied in the literature for various applications. As a subclass of ionic liquids, redox ionic liquids can endow charge exchange properties (electrons transfer) to these electrolytes for electrochemical energy storage . In this review article, we propose to study this family of ionic liquids and suggest a chronological classification. We introduce five generations of redox ionic liquids with different basic compounds such as polyethylene glycol , ferrocene , different linker lengths, TFSI anion, and biredox ionic liquids. The versatility of the redox ionic liquids synthesis will be discussed as well as the fundamental and applied aspects of their use as electrolytes, which have high charge densities. The impact of the redox ionic liquids on the electrochemical mechanisms will be described. We also present how the redox shuttle effect , detrimental to supercapacitors , can be prevented while it can be used to improve lithium-ion batteries.