Nuclear magnetic resonance studies of the solvation structures of a high-performance nonaqueous redox flow electrolyte

JOURNAL OF POWER SOURCES

卷:308

Article

Deng, Xuchu^1,2  Hu, Mary²  Wei, Xiaoliang²  Wang, Wei²  Mueller, Karl T.^2,3  Chen, Zhong¹  Hu, Jian Zhi² 

[1] Xiamen Univ, Dept Elect Sci, Xiamen 361005, Peoples R China

[2] Pacific NW Natl Lab, JCESR, Richland, WA 99352 USA

[3] Penn State Univ, Dept Chem, University Pk, PA 16802 USA

关键词: Electrolyte;    Nuclear magnetic resonance;    Nonaqueous redox flow battery;    Solvation structures;    Molecular dynamics;   

DOI  :  10.1016/j.jpowsour.2015.12.005

来源: Elsevier

【 摘 要 】

Understanding the solvation structures of electrolytes is important for developing nonaqueous redox flow batteries that hold considerable potential for future large scale energy storage systems. The utilization of an emerging ionic-derivatived ferrocene compound, ferrocenylmethyl dimethyl ethyl ammonium bis(trifluoromethanesulfonyl)imide (Fc1N112-TFSI), has recently overcome the issue of solubility in the supporting electrolyte. In this work, C-13, H-1 and O-17 NMR investigations were carried out using electrolyte solutions consisting of Fc1N112-TFSI as the solute and the mixed alkyl carbonate as the solvent. It was observed that the spectra of C-13 experience changes of chemical shifts while those of O-17 undergo linewidth broadening, indicating interactions between solute and solvent molecules. Quantum chemistry calculations of both molecular structures and chemical shifts (C-13, H-1 and O-17) are performed for interpreting experimental results and for understanding the detailed solvation structures. The results indicate that Fc1N112-TFSI is dissociated at varying degrees in mixed solvent depending on concentrations. At dilute solute concentrations, most Fc1N112(+) and TFSI- are fully disassociated with their own solvation shells formed by solvent molecules. At saturated concentration, Fc1N112(+)-TFSI- contact ion pairs are formed and the solvent molecules are preferentially interacting with the Fc rings rather than interacting with the ionic pendant arm of Fc1N112-TFSI. (C) 2016 Elsevier B.V. All rights reserved.

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