Designing Pyrrolidinium-Based Ionic Liquid Electrolytes for Energy Storage: Thermal and Electrical Behaviour of Ternary Mixtures with Lithium Salt and Carbonates

Ionic liquids (ILs) have attracted increasing attention due to their unique physicochemical properties. Among them, 1-Methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, emerges as an ideal candidate for fundamental studies in electrochemical applications. This work aims to deepen the u...

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Main Authors: Antía Santiago-Alonso, José M. Sánchez-Pico, Raquel San Emeterio, María Villanueva, Juan José Parajó, Josefa Salgado
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Applied Sciences
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Online Access:https://www.mdpi.com/2076-3417/15/8/4354
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author Antía Santiago-Alonso
José M. Sánchez-Pico
Raquel San Emeterio
María Villanueva
Juan José Parajó
Josefa Salgado
author_facet Antía Santiago-Alonso
José M. Sánchez-Pico
Raquel San Emeterio
María Villanueva
Juan José Parajó
Josefa Salgado
author_sort Antía Santiago-Alonso
collection DOAJ
description Ionic liquids (ILs) have attracted increasing attention due to their unique physicochemical properties. Among them, 1-Methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, emerges as an ideal candidate for fundamental studies in electrochemical applications. This work aims to deepen the understanding of its conductivity performance, and potential interaction with added metal salts, providing insight into its applicability in advanced energy storage systems. Firstly, binary mixtures with ethylene carbonate have been prepared to improve the transport properties and select the optimal concentration of both components. Subsequently, lithium salt was added to design the adequate electrolyte. The thermal and electrochemical characterisation of these mixtures was performed by differential scanning calorimetry (DSC) thermogravimetric analysis (TGA) and Broad Band Dielectric Spectroscopy (BBDS). The results reveal a wide liquid range for the ternary systems studied, extending below −80 °C and above 120 °C. Additionally, they exhibit notably high conductivity values at room temperature (ranging from 0.2 S·m<sup>−1</sup> for the most concentrated to 0.70 S·m<sup>−1</sup> for the lowest concentrated), which highlights their suitability for advanced electrochemical applications, including but not limited to batteries. This extended liquid phase mitigates, or potentially eliminates, some of the most common issues associated with current electrolytes, such as undesired crystallisation at low temperatures. In this paper, a new promising electrolyte, consisting of a ternary mixture obtained by adding lithium salt to the eutectic composition of [C<sub>3</sub>C<sub>1</sub>Pyrr][TFSI] and ethyl carbonate is proposed.
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spelling doaj-art-e17ab83c27ac4e61a55be26f2f747aa52025-08-20T02:17:24ZengMDPI AGApplied Sciences2076-34172025-04-01158435410.3390/app15084354Designing Pyrrolidinium-Based Ionic Liquid Electrolytes for Energy Storage: Thermal and Electrical Behaviour of Ternary Mixtures with Lithium Salt and CarbonatesAntía Santiago-Alonso0José M. Sánchez-Pico1Raquel San Emeterio2María Villanueva3Juan José Parajó4Josefa Salgado5NAFOMAT Group, Departamentos de Física Aplicada y Física de Partículas, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, SpainNAFOMAT Group, Departamentos de Física Aplicada y Física de Partículas, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, SpainNAFOMAT Group, Departamentos de Física Aplicada y Física de Partículas, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, SpainNAFOMAT Group, Departamentos de Física Aplicada y Física de Partículas, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, SpainNAFOMAT Group, Departamentos de Física Aplicada y Física de Partículas, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, SpainNAFOMAT Group, Departamentos de Física Aplicada y Física de Partículas, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, SpainIonic liquids (ILs) have attracted increasing attention due to their unique physicochemical properties. Among them, 1-Methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, emerges as an ideal candidate for fundamental studies in electrochemical applications. This work aims to deepen the understanding of its conductivity performance, and potential interaction with added metal salts, providing insight into its applicability in advanced energy storage systems. Firstly, binary mixtures with ethylene carbonate have been prepared to improve the transport properties and select the optimal concentration of both components. Subsequently, lithium salt was added to design the adequate electrolyte. The thermal and electrochemical characterisation of these mixtures was performed by differential scanning calorimetry (DSC) thermogravimetric analysis (TGA) and Broad Band Dielectric Spectroscopy (BBDS). The results reveal a wide liquid range for the ternary systems studied, extending below −80 °C and above 120 °C. Additionally, they exhibit notably high conductivity values at room temperature (ranging from 0.2 S·m<sup>−1</sup> for the most concentrated to 0.70 S·m<sup>−1</sup> for the lowest concentrated), which highlights their suitability for advanced electrochemical applications, including but not limited to batteries. This extended liquid phase mitigates, or potentially eliminates, some of the most common issues associated with current electrolytes, such as undesired crystallisation at low temperatures. In this paper, a new promising electrolyte, consisting of a ternary mixture obtained by adding lithium salt to the eutectic composition of [C<sub>3</sub>C<sub>1</sub>Pyrr][TFSI] and ethyl carbonate is proposed.https://www.mdpi.com/2076-3417/15/8/4354aprotic ionic liquidternary mixturesorganic cosolventslithium-ion batteriesthermal propertiesionic conductivity
spellingShingle Antía Santiago-Alonso
José M. Sánchez-Pico
Raquel San Emeterio
María Villanueva
Juan José Parajó
Josefa Salgado
Designing Pyrrolidinium-Based Ionic Liquid Electrolytes for Energy Storage: Thermal and Electrical Behaviour of Ternary Mixtures with Lithium Salt and Carbonates
Applied Sciences
aprotic ionic liquid
ternary mixtures
organic cosolvents
lithium-ion batteries
thermal properties
ionic conductivity
title Designing Pyrrolidinium-Based Ionic Liquid Electrolytes for Energy Storage: Thermal and Electrical Behaviour of Ternary Mixtures with Lithium Salt and Carbonates
title_full Designing Pyrrolidinium-Based Ionic Liquid Electrolytes for Energy Storage: Thermal and Electrical Behaviour of Ternary Mixtures with Lithium Salt and Carbonates
title_fullStr Designing Pyrrolidinium-Based Ionic Liquid Electrolytes for Energy Storage: Thermal and Electrical Behaviour of Ternary Mixtures with Lithium Salt and Carbonates
title_full_unstemmed Designing Pyrrolidinium-Based Ionic Liquid Electrolytes for Energy Storage: Thermal and Electrical Behaviour of Ternary Mixtures with Lithium Salt and Carbonates
title_short Designing Pyrrolidinium-Based Ionic Liquid Electrolytes for Energy Storage: Thermal and Electrical Behaviour of Ternary Mixtures with Lithium Salt and Carbonates
title_sort designing pyrrolidinium based ionic liquid electrolytes for energy storage thermal and electrical behaviour of ternary mixtures with lithium salt and carbonates
topic aprotic ionic liquid
ternary mixtures
organic cosolvents
lithium-ion batteries
thermal properties
ionic conductivity
url https://www.mdpi.com/2076-3417/15/8/4354
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