WCAcaps - From fundamental research to application...? Using electrochemically and temperature stable novel fluorinated aluminate salts as electrolytes for super-capacitors

• Applicants: Professor Dr. Ingo Krossing; Dr. Jens Tübke
• Subject Area: Synthesis and Properties of Functional Materials
• Term: from 2010 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 180161200

Recent research showed that supercapacitors based on electrochemically stable Ionic Liquid electrolytes are superior lo many conventional solvent based materials.With this project we want to apply a novel anion type, the fluorinated alkoxyaluminates [A1(0RF)4]- (especially RF = C(H)(CF3)2 and C(CF3)3), that was used in the past primarily as weakly coordinating anion (WCA) to prepare stable salts of chemically very reactive cations, as electrolytes for electrical double-layer capacitors (EDLC). Several of salts of the [A1(0RF')4]- family of WCAs form room temperature Ionic Liquids with low viscosity and high conductivity. Moreover, these WCAs are electrochemically very stable (e.g. up to +5.5 V vs. Li/Li+).These features point to a great potential of these also moderately priced WCAs to act as favourable electrolytes for EDLC devices. Also the size of the WCAs may be changed by varying RF and thus the effect of pore sizes in the solid electrodes may also be investigated in detail. During the project, three subsequent generations of [Al(ORF )4]- electrolytes shall be developed and fully tested in EDLCs. After each generation a careful assessment of the performance of the EDLC devices shall be done and results should be correlated with physical properties of the used WCA electrolytes as well as the electrode materials. An understanding of the reasons for failure or success of the WCA electrolytes shall be supported by quantum chemical calculations of relevant properties.

• DFG Programme: Research Grants