Solvent-Free ILs for Pseudocapacitors

Other less expensive metal oxides such as Mn oxide have also been investigated as electrode materials in ILs. Chang et al. [661] fonnd that it was possible to achieve the 

FIGURE 2.76 Normalized infrared absorbance of the cation and anion of the IL in electrodes with RuOj contents of (a) 22, (b) 35, and (c) 48 wt.% during CV scans from —1.5 to +1.5 V at a scan rate of 5 mV s. Cross-sectional SEM images showing the structure of porous electrodes with RuOj contents of (d) 22, (e) 35, and (f) 48 wt.%. (Reproduced by permission of The Electrochemical Society from Richey, E. W., and Y. A. Elabd. 2013. Journal of the Electrochemical Society 160 A862-A868) 

The reaction thickness was found to be about 50 nm by XPS depth profiling analyses. A potential window of 3 V could be achieved for Mn oxide electrode in the [BMP][DCA] IL. Similar results were found for the [EMIM][DCA] IL electrolyte, and the penetration depth of [DCA] into Mn oxide was found to be about three times deeper than that of [BFJ . This contributed to a much higher specific capacitance of the Mn oxide electrode in [EMIM][DCA] (72 F g- ) compared with that obtained in 

In addition to the increase of the working voltage, the use of IL as the electrolyte have also been found to improve the performance of the MnOj-based pseudocapacitors at high temperatures (e.g., 80 C) whereas Mn02-based pseudocapacitors using aqueous electrolyte showed a deteriorated performance [668], 

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