Abstract
Understanding the mechanisms controlling ionic conductivity is critical for the development of the next generation of batteries and supercapacitors. This paper discusses the significant role played by ionic correlations in conductivity of concentrated ionic systems. Our studies of an organic ionic plastic crystal reveal that correlations in ions dynamics suppress conductivity by 25-100 times in comparison to the expected uncorrelated ionic conductivity estimated from the Nernst-Einstein relationship. Additional analysis also demonstrates that ionic correlations suppress conductivity in polymerized ionic liquids and gel by ∼10 times. Thus, ionic correlations, usually neglected in many studies, play a very important role in conductivity of concentrated ionic systems. These results cannot be explained by a diffusion of ion pairs because all these systems are essentially single ion conductors. In contrast, strongly correlated motions of mobile ions with the same charge (cation-cation or anion-anion correlations) are the major mechanism suppressing the ionic conductivity in these systems. On the basis of these results, we emphasize that charge transport rather than ion diffusion is critical for electrolyte performance and suggest the potential design of plastic crystals and polymer electrolytes with enhanced ionic conductivity.
| Original language | English |
|---|---|
| Pages (from-to) | 17889-17896 |
| Number of pages | 8 |
| Journal | Journal of Physical Chemistry C |
| Volume | 124 |
| Issue number | 33 |
| DOIs | |
| State | Published - Aug 20 2020 |
Funding
I.P. and A.P.S. acknowledge support by the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences for the BDS measurements and data analysis. A.P.S thanks Deakin University for hospitality during January-February 2019. B.K. thanks the University of Tennessee for hospitality. Kh.A.A. is thankful to the Russian Government Program of Competitive Growth of Kazan Federal University for partial support of the research. M.F. thanks ARC LIEF grant LE110100141 for funding Deakin University’s NMR facility. ARC is also acknowledged for funding the Centre of Excellence for Electromaterials Science. C.G. acknowledges the financial support from Deutsche Forschungsgemeinschaft under Project No. GA2680/1-1. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). Acknowledgments