WCAcaps - From fundamental research to application...? Using electrochemically and temperature stable novel fluorinated aluminate salts as electrolytes for super-capacitors
Zusammenfassung der Projektergebnisse
The initial final goal of the project was the development of a competitive supercapacitor comprising an ionic liquid (IL) with highly fluorinated, weakly coordinating aluminate anions as electrolyte. Other goals were the development and investigation of novel ILs. Although the construction of a truly competitive supercapacitor could not be realized during the project due to the discovered incompatibility of highly fluorinated aluminate anions with state-of-the-art high-capacitance electrodes, much progress concerning the synthesis of novel classes of ILs and investigation of their transport properties was made, which led to tremendous insight into the fundamental interactions governing dynamic properties such as electrical conductivity and viscosity. The individual achievements were: 1) The synthesis and thorough characterization of beforehand unknown classes of ILs with: a) Siloxane-functionalized imidazolium cations; b) [(CF3)2(H)COSO3]-anions; c) [B(OCH(CF3)2)4]-anions; d) [B(OCH2CF3)4]-anions; e) Fluorinated imidazolium cations and highly fluorinated aluminate anions. 2) The prove of a molecular sieving effect at microporous carbon electrodes when combined with ILs comprising highly fluorinated [Al(OCH(CF3)2)4]─ anions, which hinders diffusion into micropores and thus drastically limits capacitance and energy density by decreasing the available surface area. 3) The testing of [Al(OCH(CF3)2)4]-ILs with novel graphene electrodes. These tests yielded promising results, for instance capacitances, which were up to 400% as high as in the case of microporous carbon electrodes. 4) The improvement of electrolyte properties of [Al(OCH(CF3)2)4]-ILs by mixing them with either dimethyl carbonate or other highly fluorinated ILs. 5) A systematic study of the transport properties of 24 ILs. This study, combined with a modified theory, led to the conclusion that an anion diameter of roughly 1 nm yield the lowest activation energies for transport processes in ionic liquids. 6) A consistent predictive model allowing for the calculation of thermodynamic properties of ILs with the help of quantum-mechanical calculations. This model meanwhile has been incorporated in the “CosmoThermX” software package. In the course of the WCAcaps project, 11 peer-reviewed papers in high-class scientific journals have been published. Amongst these publications is one comprehensive review article summarizing all results about ionic liquids, which have been obtained by us in the last years as well as four dissertations. Furthermore, results from the WCAcaps project were presented at more than a dozen national and international conferences and meetings.
Projektbezogene Publikationen (Auswahl)
-
New water-stable Ionic Liquids based on Tetrakis-(2,2,2-trifluoroethoxy)borate. ChemPhysChem 2014, 15, 3729-3731
Alexander B. A. Rupp, Petra Klose, Harald Scherer, Ingo Krossing
-
Size Matters! On the Way to Ionic Liquid Systems without Ion Pairing. Chemistry – A European Journal 2014, 20, 9794-9804
Alexander Rupp, Nataliya Roznyatovskaya, Harald Scherer, Witali Beichel, Petra Klose, Carola Sturm, Anke Hoffmann, Jens Tübke, Thorsten Koslowski, Ingo Krossing
-
“Straightforward Synthesis of the Brønsted Acid hfipOSO3H and its Application for the Synthesis of Protic Ionic Liquids.” Angew. Chem. Int. Ed. 2014, 53, 6637-6640
W. Beichel, Panzer, Johann M. U., J. Hätty, X. Ye, D. Himmel, I. Krossing
-
Effect of Dimethyl Carbonate on the Dynamic Properties and Ionicities of Ionic Liquids with [MIII(hfip)4]– (M=B, Al) Anions. ChemPhysChem 2015, 16, 1940-1947
Alexander B. A. Rupp, Sabrina Welle, Petra Klose, Harald Scherer, Ingo Krossing
-
Ionic Liquids with Weakly Coordinating [MIII(ORF)4]− Anions. Acc. Chem. Res. 2015, 48, 2537-3546
Alexander B. A. Rupp, Ingo Krossing
-
Sieving Effects in Electric Double-Layer Capacitors Based on Neat [Al(hfip)4]– and [NTf2]– Ionic Liquids. ChemElectroChem 2015, 2, 829-836
Nataliya Roznyatovskaya, Alexander B. A. Rupp, Jens Tübke, Ingo Krossing
