Viscosity of a Ternary Reciprocal System Consisting of 1-Alkylpyridinium Halides

Viscosity of Ionic Liquids: Theories and Models

Ionic liquids (ILs) offer a wide range of promising applications due to their unique and designable properties compared to conventional solvents. Further development and application of ILs require correlating/predicting their pressure-viscosity-temperature behavior. In this review, we firstly introduce methods for calculation of thermodynamic inputs of viscosity models. Next, we introduce theories, theoretical and semi-empirical models coupling various theories with EoSs or activity coefficient models, and empirical and phenomenological models for viscosity of pure ILs and IL-related mixtures. Our modelling description is followed immediately by model application and performance. Then, we propose simple predictive equations for viscosity of IL-related mixtures and systematically compare performances of the above-mentioned theories and models. In concluding remarks, we recommend robust predictive models for viscosity at atmospheric pressure as well as proper and consistent theories and models for P-η-T behavior. The work that still remains to be done to obtain the desired theories and models for viscosity of ILs and IL-related mixtures is also presented. The present review is structured from pure ILs to IL-related mixtures and aims to summarize and quantitatively discuss the recent advances in theoretical and empirical modelling of viscosity of ILs and IL-related mixtures.

Electrical Double-Layer Capacitors Based on a Ternary Ionic Liquid Electrolyte Operating at Low Temperature with Realistic Gravimetric and Volumetric Energy Outputs

We report on electrical double-layer capacitors (EDLCs) performing effectively at low temperature (down to -40 °C), owing to the tuned characteristics of both the ionic liquid (IL) electrolyte and carbonaceous electrodes. The transport properties of the electrolyte have been enhanced by adding a low-viscosity IL with the tetracyanoborate anion, [EMIm][TCB], to a mixture of [EMIm][FSI] with [EMIm][BF₄ ], which was already successfully applied for this application. The formulated ternary electrolyte, [EMIm][FSI]_0.6 [BF₄ ]_0.1 [TCB]_0.3 , remained in the liquid state until it reached the glass transition at -99 °C and displayed a relatively low viscosity and high conductivity (η=23.6 mP s and σ=14.2 mS cm^-1 at 20 °C, respectively). The electrodes were made of a hierarchical SiO₂ -templated carbon with well-defined and uniform mesopores of ∼9 nm facilitating ion transport to the interconnected micropores accounted for the charge storage, whereas the high density of the electrodes promoted high volumetric energy outputs of the cells.

Viscosity models for ionic liquids and their mixtures

Review of principles and limitations of viscosity models for ionic liquids and their mixtures focusing on the use of inappropriate mixing rules for molten salts.