Ionic Liquids & Electrolytes

The first ionic liquids with the tetracyanoborate anion [B(CN)₄]^– (TCB) marked the beginning of cyanoborate-ILs. Since then, low-viscous cyanoborate-ILs that provide high thermal, chemical, and electrochemical stabilities have been developed. In addition metal salts have been studied. The salt properties are adjusted by the substituents attached to boron, i.e. perfluoroalkyl, alkyl, fluorine and hydrogen substituents among others. Our current studies include the development of ILs and metal salts with tailor-made properties for energy-related applications.

Publications on this topic:

Cyano(fluoro)borate and cyano(hydrido)borate ionic liquids: Low-viscosity ionic media for electrochemical applications
J. Riefer, L. Zapf, J. A. P. Sprenger, R. Wirthensohn, S. Endres, A.-C. Pöppler, M. Gutmann, L. Meinel, N. V. Ignat’ev, M. Finze, Phys. Chem. Chem. Phys. (PCCP) 2023, DOI: 10.1039/D1032CP05725E.

Innovative Syntheses of Cyano(fluoro)borates: Catalytic Cyanation, Electrochemical and Electrophilic Fluorination 
M. Drisch, L. A. Bischoff, J. A. P. Sprenger, P. T. Hennig, R. Wirthensohn, S. Z. Konieczka, M. Hailmann, N. V. Ignat'ev, M. Finze, Chem. Eur. J. 2020, 26, 11625–11633.

Cyanohydridoborate Anions: Synthesis, Salts, and Low-Viscosity Ionic Liquids 
N. V. Ignat’ev, M. Finze, Eur. J. Inorg. Chem. 2019, 3539–3560.

Boron: Its Role in Energy-Related Processes and Applications 
Z. Huang, S. Wang, R. D. Dewhurst, N. V. Ignat’ev, M. Finze, H. Braunschweig, Angew. Chem. Int. Ed. 2020, 59, 8800–8816.

Cyanoborates 
N. V. Ignat’ev, M. Finze, Eur. J. Inorg. Chem. 2019, 3539–3560.

The introduction of pentafluoroethyl groups at phosphorous typically results in phosphate anions with interesting properties. For example, IL-properties such as viscosity and conductivity can be tuned, which is the basis for many applications of these low-melting salts. In addition, metal salts for battery applications are studied. Similarly, perfluorinated sulfonylimide anions are standard components in electrolyte and ionic IL chemistry. We are especially interested in the influence of anion size, mass, and flexibility on materials properties.

Publications on this topic:

Insights to structure-property relationships in ionic liquids using cyclic perfluoroalkylsulfonylimides
Y. K. J. Bejaoui, F. Philippi, H.-G. Stammler, K. Radacki, L. Zapf, N. Schopper, K. Goloviznina, K. A. M. Maibom, R. Graf, J. A. P. Sprenger, R. Bertermann, H. Braunschweig, T. Welton, N. V. Ignat’ev, M. Finze, Chem. Sci. 2023, 14, DOI: 10.1039/D1032SC06758G.

New Hydrophobic Ionic Liquids with Perfluoroalkylphosphate and Cyanofluoroborate Anions 
N. V. Ignat’ev, M. Finze, J. A. P. Sprenger, C. Kerpen, E. Bernhardt, H. Willner, J. Fluorine Chem. 2015, 177, 46–54.