Research Advances in Electrochemical Window of Ionic Liquids

Based on the status quo of the application of ionic liquids and their electrochemical window, a large number of electrochemical window data from domestic and foreign research sources of ionic liquids are summarized, including chloroaluminate systems, imidazolium, quaternary ammonium salts, etc. The electrochemical windows of ionic liquids depend on their cations and anions, working electrodes and reference electrodes. Through analyzing the above factors, it is obtained that the cathodic limiting potential of ionic liquids decreases in the following order: ammonium ≈ phosphonium pyrrolidinium piperidinium ≈ morpholinium azepanium ≈ imidazolium sulfoniumpyridinium. The anodic limiting potential of ionic liquids has the following sequence: NTf2- ≈ RFBF3- BF4- TSAC- F(HF)2.3- CF3COO- HCOO-. Furthermore, the electrochemical windows gradually become narrow on different working electrodes in the order: W GC Pt ≈ Au. Tungsten is the best working electrode material for studies on ionic liquids. The potential measured vs. Li/Li+ is the most positive.