Asymmetrical imidazolium-trialkylammonium room temperature dicationic ionic liquid electrolytes for Li-ion batteries

Fluorinated Linkers Enable High-Voltage Pyrrolidinium-based Dicationic Ionic Liquid Electrolytes

Novel fluorinated, pyrrolidinium-based dicationic ionic liquids (FDILs) as high-performance electrolytes in energy storage devices have been prepared, displaying unprecedented electrochemical stabilities (up to 7 V); thermal stability (up to 370 °C) and ion transport (up to 1.45 mS cm-1). FDILs were designed with a fluorinated ether linker and paired with TFSI/FSI counterions. To comprehensively assess the impact of the fluorinated spacer on their electrochemical, thermal, and physico-chemical properties, a comparison with their non-fluorinated counterparts was conducted. With a specific focus on their application as electrolytes in next-generation high-voltage lithium-ion batteries, the impact of the Li-salt on the characteristics of dicationic ILs was systematically evaluated. The incorporation of a fluorinated linker demonstrates significantly superior properties compared to their non-fluorinated counterparts, presenting a promising alternative towards next-generation high-voltage energy storage systems.

Environmental impact assessment of dicationic ionic liquids with ammonium-phosphonium cations and amino acid anions

Progress in the development of biodegradable or biobased ionic liquids (ILs) has led to the design of green compounds for several applications. Herein, four biocompatible dicationic ionic liquids (DILs) with ammonium-phosphonium cations and amino acid anions were synthesized and investigated their environmental impact. The structures of the DILs were confirmed by spectral analyses (1H, 13C and 31P NMR). Furthermore, physicochemical properties such as density, viscosity and refractive index were determined. Water content, bromide content and solubility were thereafter determined as the parameters needed for further studies. Subsequently, their antifeedant activity towards economically important pests of grain in storage warehouses: the granary weevil, the confused flour beetle, and the khapra beetle was examined, showing the dependence on structure. Moreover, selected DILs were investigated for toxicity towards white mustard, Daphnia magna, and Artemia franciscana to specify the environmental impact. These studies were complemented by understand the biodegradation of DILs by bacterial communities derived from soil at the agricultural land. The result was DILs with limited environmental footprints that have great potential for further application studies.

Imidazolium ionic liquids as potential persistent pollutants in aqueous environments: Indirect photochemical degradation kinetics and mechanism

Ionic liquids (ILs) with promising application are likely to become ubiquitous contaminants in water environment for their high hydrophilicity, low biodegradability, and especially its potential toxicity. In this work, we have investigated photochemical transformation of six imidazolium ILs for fate prediction and ecological risk assessment. We found that the reaction rates of the ILs with •OH, CO₃^•─ and ¹O₂ enhanced with their increasing alkyl chain and varied slightly with the paired anions. Meanwhile, modelled results under different scenarios indicate that the primary contributors to transformation of the ILs are triplet-stated dissolved matter (³CDOM*), •OH and CO₃^•-. Besides, the overall half-lives of the ILs can reach 670 days, which indicates persistence of these ILs in the environment. Products for ILs in reaction with •OH and triplet-stated sodium anthraquinone-2-sulfonate (³AQ2S*) were probed by UHPLC-Q-TOF-MS/MS and there is a difference between their products: Products by •OH are likely formed by hydrogen abstraction from the side alkyl chain, followed by dehydrogenation, hydroxylation and carbonylation, while one of the products by ³AQ2S* is formed by dihydroxyl-addition of the imidazolium ring. Furthermore, the ILs and its products were estimated to have toxicity and non-readily biodegradability, suggesting potential eco-risk for the environmental water.

Plastic crystal-based electrolytes using novel dicationic salts

The unique structures of dications increase the number of possible combinations of cations and anions that can be used to obtain new materials with a wide range of physicochemical properties. However, structure-property relationships related to dicationic organic salts are seldom explored. Here, we report the synthesis and characterization of two new dicationic salts, 1,2-bis(N-ethylpyrrolidinium)ethane bis(trifluoromethanesulfonyl)imide ([C₂-Pyrr2][TFSI]₂) and 1,2-bis(N-n-propylpyrrolidinium)ethane bis(trifluoromethanesulfonyl)imide ([C₂-Pyrr3][TFSI]₂). To investigate the physicochemical properties of the organic salts, local structure and dynamics were investigated by variable temperature solid-state NMR and correlated with the thermal analysis and ionic conductivity. These studies revealed that [C₂-Pyrr3][TFSI]₂, with the longer alkyl-side chain on the dication, showed improved transport properties compared to [C₂-Pyrr2][TFSI]₂. Further exploration of the organic salts as potential electrolyte materials was conducted by mixing with 10 mol% lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). This study demonstrates the effect that lithium salt addition has on thermal and ionic conductivity properties, where the largest increase in conductivity was found for [C₂-Pyrr3][TFSI]₂/LiTFSI (10 mol% LiTFSI). Solid-state NMR analysis revealed that Li⁺ and [TFSI]^- ions acted as the major contributors to ionic conductivity while the dications in the bulk structure showed lower mobility.

Properties and Recent Advantages of N,N’-dialkylimidazolium-ion Liquids Application in Electrochemistry

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N,Nʹ-dialkylimidazolium-ion liquids is one of the important ionic liquids with a wide range of application as conductive electrolyte and in electrochemistry. The modified electrodes create a new view in fabrication of electroanalytical sensors. Many modifiers have beeen suggested for modification of electroanalytical sensor since many years ago. Over these years, ionic liquids and especially room temperature ionic liquids have attracted more attention due to their wide range of electrochemical windows and high electrical conductivity. N,Nʹ-dialkylimidazolium-ion liquids are one of the main important ionic liquids suggested for modification of bare electrodes and especially carbon paste electrodes. Although many review articles have reported onthe use of ionic liquids in electrochemical sensors, no review article has been specifically introduced so far on the review of the advantages of N,Nʹ-dialkylimidazolium ionic liquid. Therefore, in this review paper we focused on the introduction of recent advantages of N,Nʹ-dialkyl imidazolium ionic liquid in electrochemistry.