Colloquium: Nanoscale structure of a hybrid aqueous–nonaqueous electrolyte

ABSTRACT

A new class of electrolytes has been reported, hybridizing aqueous with non-aqueous solvents, which combines the non-flammability and non-toxicity characteristics of aqueous electrolytes with the superior electrochemical stability of non-aqueous systems. Here we report measurements of the structure of an electrolyte composed of an equal-mass mixture of 21 m LiTFSI-water and 9 m LiTFSI-dimethyl carbonate using high-energy x-ray diffraction and polarized neutron diffraction with isotope substitution.1 The neutron structure factors from the partially and fully deuterated samples exhibit peaks at low scattering vector Q that we ascribe to long-range correlations involving both the solvent molecules and the TFSI- anions. We compare both sets of measurements with results of Molecular Dynamics simulations based on a polarizable force field. The structures derived from the simulations are generally in agreement with those measured, except that the neutron structure factors predicted for the two partially deuterated samples show very intense scattering increasing up to the low-Q limit of the simulation, indicating a partial segregation between the two solvents not observed in the experimental measurements. These results will be compared with those from our earlier work on “water-in-salt” electrolytes and a “water-in-bisalt” electrolyte.2

REFERENCES

(1) M.-L. Saboungi et al., J. Chem. Phys., 2023, 158, 124502; (2) M. A. González et al., J. Phys. Chem. Lett., 2020, 11, 7279.

BIOGRAPHY

Prof. Marie-Louise Saboungi is Distinguished Professor of Physics, University of Orleans, CNRS and Pierre et Marie Curie University, France. She was Director of research institute, University of Orleans for 10 years, as Co-Director of the Materials, Energy and Geosciences Thrust Area at University of Orleans for five years and as a Research and Education Minister nominee of the National Committee for the promotion of the Associate and Assistant Professors of the French Universities. Prior to that she was a Senior Scientist at Argonne National Laboratory, where she established close collaborations with the University of Chicago and Cornell University. She is Fellow of the AAAS, the APS and the Alexander von Humboldt Foundation, from which she received the Helmholtz-Humboldt Prize. She served on international advisory committees and national committees for DOE and NSF in US, for CNRS, ANR and AERES in France, and she is a member of the Advisory Board of the FET-Horizon in EC.