Thermal, electrochemical and radiolytic stabilities of ionic liquids

Abstract

Research on ionic liquids has achieved rapid progress in the last several decades. Stability is a prerequisite for the application of ionic liquids. Ionic liquids may be used at elevated temperature, as electrolytes, or under irradiation. Therefore, the thermal, electrochemical, and radiolytic stabilities of ionic liquids are important and need to be known before their usage. Many research papers and some reviews on the stabilities of ionic liquids have been published. However, new results are continuously being published and a comprehensive review and perspective on this topic are still urgently needed. In this perspective, we intend to provide a comprehensive review including characterization methods, the effects of chemical composition of the ionic liquids on the thermal, electrochemical, and radiolytic stabilities of ionic liquids, respectively. Moreover, the thermal stability of some special types of ionic liquids such as poly(ionic liquids) and mixed ionic liquids, and the thermal and electrochemical stabilities of protic ionic liquids are discussed too. For thermal stability, the interactions between ions are less important than the individual anions and cations. The decomposition temperature is mainly determined by the less-stable ion, usually the anion. For electrochemical stability, the electrochemical window is determined by both the cation and anion. The less stable ion could influence the stability by interaction between the generated species from the decomposition with the more stable ion (opposite ion). This perspective is helpful for people to avoid using unstable ionic liquids and choose suitable ionic liquids.

Advances in sodium secondary batteries utilizing ionic liquid electrolytes

“…Non-aromatic pyrrolidinium-based cations are reductively more stable than imidazolium-based cations, and thus widely utilised for secondary battery applications. 141 In a recent study, the physicochemical properties of a range of cationic structures (ammonium, pyrrolidinium, piperidinium, and morpholinium) in the forms of FSA-and TFSA-based ILs were systematically studied, revealing the preferable features of ether-functionalised cations. 131 Two additional categories are briefly considered here; inorganic ILs and solvate ILs.…”

Ion speciation: a key for the understanding of the solution properties of ionic liquid mixtures

“…1 Care should be taken as current findings show that some ionic liquids have remarkably different chemical and thermal stability. 2,3 Nevertheless, the main interest of ionic liquids arises from the possibility to tune their chemical and physical properties by the suitable selection of a cation and an anion, making them designer solvents. In recent years, the design of ionic liquids has been taken to the next level by mixing two (or more) ionic liquids to achieve the desired properties, creating ionic liquid mixtures.…”

Functional mesoporous poly (ionic liquid) derived from P123: From synthesis to catalysis and alkylation of styrene and o‐xylene

“…Poly (ionic liquid) s (PILs) are an emerging class of functional polymers that are comprised of ionically charged repeating units typically used in ionic liquid chemistry . As a burgeoning interdisciplinary topic, PILs are attracting increasing interest due to the combination of the unique properties of IL with the macromolecular architecture and creating new properties and functions . Recently, a series of PIL materials have been synthesized by introducing functional cationic and anionic IL groups into dynamic macromolecular polymeric architectures which have broadened PIL properties, structures, functionalities and applications .…”

“…[22][23][24][25] As a burgeoning interdisciplinary topic, PILs are attracting increasing interest due to the combination of the unique properties of IL with the macromolecular architecture and creating new properties and functions. [26][27][28] Recently, a series of PIL materials have been synthesized by introducing functional cationic and anionic IL groups into dynamic macromolecular polymeric architectures which have broadened PIL properties, structures, functionalities and applications. [29][30][31][32] PILs have been widely used in catalysis due to the functiondesignability and eco-friendly quality.…”