Liquid and Polymer-Electrolytes
In the current demand for sustainable energy supplies, the development and optimization of energy storage systems is of increasing relevance. Today, Li batteries are the most promising concept, even for high power applications. Ion- conducting polymer electrolytes are promising membrane materials separating the electrodes. General requirements for the membrane material are high ionic conductivity, high mechanical stability and processing of ultrathin films to allow fast loading processes. The optimization of any ion conductor for these purposes, however, requires a molecular understanding of ion transport processes.
Our activities in this field consist of multinuclear NMR (1H, 7Li, 19F) studies of electrolytes, which provide a combined approach of ion diffusion (PFG-NMR), ion conductivity and spin relaxation. We investigate salt-in-polymer-electrolytes, ionic liquids, carbonate-based electrolytes ans polymer gel electrolytes. The results provide a detailed picture of the cation, anion and chain mobility ranging from the local intramolecular scale up to the microscopic length scale. From this, details of the ionic transport mechanisms are elucidated yielding a basis for further material optimization.
Selected publications
Nürnberg, P.; Atik, J.; Borodin, O.; Winter, M.; Paillard, E.; Schönhoff, M.
Superionicity in ionic liquid-based electrolytes induced by positive ion-ion correlations
J. Am. Chem. Soc. 2022, 144 (10), 4657–4666.
https://doi.org/10.1021/jacs.2c00818
Ackermann, F.; Schönhoff, M.
Chelating Additives Reversing the Lithium Migration Direction in Ionic Liquid Electrolytes
J. Phys. Chem. C 2021, 125, 266-274.
http://dx.doi.org/10.1021/acs.jpcc.0c09828
Pfeifer, S.; Ackermann, F.; Sälzer, F.; Schönhoff, M.; Roling, B.;
Quantification of Cation-Cation, Anion-Anion and Cation-Anion Correlations in Li Salt/Glyme Mixtures by combining Very-low-frequency Impedance Spectroscopy and Diffusion and Electrophoretic NMR
Phys. Chem. Chem. Phys. 2021, 23, 628-640.
https://doi.org/10.1039/D0CP06147F
Rosenwinkel, M.P.; Andersson, R.; Mindemark, J.; Schönhoff, M.
Coordination Effects in Polymer Electrolytes: Fast Li+ Transport by Weak Ion Binding
J. Phys. Chem. C 2020, 124, 43, 23588–23596.
https://doi.org/10.1021/acs.jpcc.0c08369
Schmidt, F.; Schönhoff, M.
Solvate Cation Migration and Ion Correlations in Solvate Ionic Liquids
J. Phys. Chem. B 2020, 124(7), 1245-1252.
http://dx.doi.org/10.1021/acs.jpcb.9b11330
Gouverneur, M.; Schmidt, F.; Schönhoff, M.
Negative effective Li transference numbers in Li salt/ionic liquid mixtures: Does Li drift in the “wrong” direction?
Phys. Chem. Chem. Phys. 2018, 20, 7470 – 7478.
https://doi.org/10.1039/C7CP08580J