TY - JOUR
T1 - An experimental and computational study of a low-temperature electrolyte design utilizing iodide-based ionic liquid and butyronitrile
AU - Lin, Wendy J.
AU - Xu, Yifei
AU - Gliege, Marisa E.
AU - Whitney, Christopher
AU - Chen, Mu Tao
AU - Gunckel, Ryan
AU - Dai, Lenore L.
N1 - Funding Information:
We gratefully acknowledge the financial support from NASA 80NSSC20K0826, NNX17AF70G and the Fulton Undergraduate Research Initiative at Arizona State University. We also acknowledge Professor Candace Chan and LeRoy Eyring Center for Solid State Science at Arizona State University for the equipment access and Research Computing at Arizona State University for providing high performance computing and storage resources that have contributed to the computational research results.
Publisher Copyright:
© 2022 The Royal Society of Chemistry.
PY - 2022
Y1 - 2022
N2 - Wide liquidus range electrolytes are in popular demand to extend the operating temperature windows of electrochemical devices. Different from conventional electrolytes, which dissolve salt in molecular liquids, highly tunable ionic liquids (ILs) offer attractive properties as competitive candidates in recent electrolyte developments. While IL-based electrolytes showcase satisfying performances at high and room temperatures, their functionality at low temperatures remains a challenge with the most reported progress around −40 to −70 °C. Herein, we present experimental and computational studies on low-temperature liquid electrolyte systems consisting of iodide containing IL, 1-butyl-3-methylimidazolium iodide ([BMIM][I]), nitrile solvents, acetonitrile (ACN) and butyronitrile (BuCN), and lithium iodide (LiI). While the [BMIM][I]/ACN/LiI system exhibits first-order phase transitions with increasing ACN concentration, [BMIM][I]/BuCN/LiI systems remain as glass-forming liquids over a wide composition range. More impressively, [BMIM][I]/BuCN/LiI-5/90/5 possesses an extremely low glass transition temperature of −152 °C, which marks the lowest liquidus range limit of reported IL-based mixtures to the best of our knowledge. Correspondingly, enhancements in transport properties are observed, especially at temperatures below −40 °C in comparison to our previous work. Moreover, iodide/triiodide electrochemistry in BuCN is validated as active and stable within the identified potential window. We attribute the bulk property evolution of the designed electrolytes to microscopic intermolecular interaction optimization, specifically, solvation of BuCN around the imidazolium cation via hydrogen bonding, as characterized using Fourier transform infrared (FTIR) and Raman spectroscopies. Furthermore, the effects of BuCN on the ion and molecular ordering are investigated through molecular dynamics simulation, which elucidates a different mechanism from IL/water mixtures. This work presents IL/BuCN systems with an exceptionally wide liquidus range and improvements in transport, which not only benefits iodide/triiodide-based technologies but also serves as a foundation for further task-specific optimization to support electrochemical devices at ultralow temperatures.
AB - Wide liquidus range electrolytes are in popular demand to extend the operating temperature windows of electrochemical devices. Different from conventional electrolytes, which dissolve salt in molecular liquids, highly tunable ionic liquids (ILs) offer attractive properties as competitive candidates in recent electrolyte developments. While IL-based electrolytes showcase satisfying performances at high and room temperatures, their functionality at low temperatures remains a challenge with the most reported progress around −40 to −70 °C. Herein, we present experimental and computational studies on low-temperature liquid electrolyte systems consisting of iodide containing IL, 1-butyl-3-methylimidazolium iodide ([BMIM][I]), nitrile solvents, acetonitrile (ACN) and butyronitrile (BuCN), and lithium iodide (LiI). While the [BMIM][I]/ACN/LiI system exhibits first-order phase transitions with increasing ACN concentration, [BMIM][I]/BuCN/LiI systems remain as glass-forming liquids over a wide composition range. More impressively, [BMIM][I]/BuCN/LiI-5/90/5 possesses an extremely low glass transition temperature of −152 °C, which marks the lowest liquidus range limit of reported IL-based mixtures to the best of our knowledge. Correspondingly, enhancements in transport properties are observed, especially at temperatures below −40 °C in comparison to our previous work. Moreover, iodide/triiodide electrochemistry in BuCN is validated as active and stable within the identified potential window. We attribute the bulk property evolution of the designed electrolytes to microscopic intermolecular interaction optimization, specifically, solvation of BuCN around the imidazolium cation via hydrogen bonding, as characterized using Fourier transform infrared (FTIR) and Raman spectroscopies. Furthermore, the effects of BuCN on the ion and molecular ordering are investigated through molecular dynamics simulation, which elucidates a different mechanism from IL/water mixtures. This work presents IL/BuCN systems with an exceptionally wide liquidus range and improvements in transport, which not only benefits iodide/triiodide-based technologies but also serves as a foundation for further task-specific optimization to support electrochemical devices at ultralow temperatures.
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U2 - 10.1039/d2me00100d
DO - 10.1039/d2me00100d
M3 - Article
AN - SCOPUS:85141058770
SN - 2058-9689
JO - Molecular Systems Design and Engineering
JF - Molecular Systems Design and Engineering
ER -