The Novel Ionic Liquid and Its Related Self‐Assembly in the Areas of Energy Storage and Conversion

Abstract

ILs unique properties such as ionic conductivity, low volatility, noninflammability, high chemical and electrochemical stability, and so on. [3] These properties coupled with adjustable structure and functionality allow ILs to evolve from unique liquid mediums to the solvents/electrolytes widely used across multiple disciplines in science and engineering. [4][5][6][7][8][9] The incorporation of ILs and advanced energy storage and conversion technology seems to be a nice strategy to meet the increasing demand for clean and sustainable energy. [10] However, traditional ILs based on ammonium, alkylpyridinium, dialkylimidazolium, and phosphonium cations, are generally expensive, nonbiodegradable, and toxicities, which are unfavorable to achieving the aforementioned goals. [11] Thus, numerous efforts have been devoted to exploring the advanced ILsderived materials, which retain most of the characteristics of ILs and are endowed with new features. Novel ILs, including deep eutectic solvents (DESs), [12,13] poly(ionic liquid)s (PILs), [14][15][16] ionic liquid crystals (ILCs), [17,18] and redox-active ionic liquids (RAILs), [19,20] have been synthesized and have been proved to be promising materials to compensate for the inadequacies of the traditional ILs.In general, those four types of novel ILs exhibit unique features and advantages in the fields of energy storage and conversion, respectively. For example, DESs are inexpensive, biodegradable, and nontoxic, they have great advantages in building environmental-friendliness energy storage devices. [21,22] The PILs have a polymeric structure while maintaining ionic conductivity. This means they are excellent potential materials for preparing binder, membranes, and solid-state electrolyte. [23] They are also a kind of building blocks for self-assembly. ILCs with enhanced ordered structure and unique phase behavior are able to achieve the efficient and directional conduction of species, which are excellent properties to construct high-performance energy storage devices. [24] Besides, RAILs are a liquid material with ionic conductivity and redox centers and have exhibited promising potentiality for use as redox additives and electroactive electrolytes. [25] In this review, we focus on the intrinsic properties of novel ILs and their related self-assembly behavior for constructing highperformance energy storage and conversion devices. In the following four chapters, we discuss the unique properties,

Advanced research and prospects on polymer ionic liquids: trends, potential and application

“…The progress of the emergence and use of new ILs for energy storage and conversion was noted in a brief review. 47 The following were considered as new ILs:…”

“…The work cites numerous examples and concludes that, given their unique physical and chemical properties, electrochemical behavior, and self-assembled structures, the new ILs have become promising materials for various applications, particularly energy storage and conversion. 47…”

Acid‐Base Chemistry Provides a Simple and Cost‐Effective Route to New Redox‐Active Ionic Liquids

“…Redox-active ionic liquids are attracting increasing attention in the scientific literature (Figure 1) due to their potential utility as energy harvesting and storage materials. [1][2][3] In particular, they possess a number of characteristics that make them ideal redox flow battery electrolytes: high concentrations of redox-active species and charge carriers, tunable redox potentials, low vapour pressures, and excellent thermal and chemical stabilities. [1,4,5] However, their practical utility is hampered by low ionic conductivities and the high cost of preparing bulk quantities of custom-designed, redox-functionalised ionic liquids.…”

“…[1,4,5] However, their practical utility is hampered by low ionic conductivities and the high cost of preparing bulk quantities of custom-designed, redox-functionalised ionic liquids. [1,3] For a comprehensive overview of the properties of aprotic redox-active ionic liquids and their potential applications in redox flow batteries, the interested reader is referred to a recent series of review articles and the references contained within. [1,3,5,6] Protic ionic liquids are formed by simple acid-base reactions, typically involving proton transfer from a Brønsted-Lowry acid to a Brønsted-Lowry base.…”

“…[1,3] For a comprehensive overview of the properties of aprotic redox-active ionic liquids and their potential applications in redox flow batteries, the interested reader is referred to a recent series of review articles and the references contained within. [1,3,5,6] Protic ionic liquids are formed by simple acid-base reactions, typically involving proton transfer from a Brønsted-Lowry acid to a Brønsted-Lowry base. [7,8] They often display higher conductivities than their aprotic counterparts, due in part to the existence of a Grotthuss-like proton transfer mechanism.…”