Cathodic electrosynthesis of VOx ceramics for supercapacitor applications

The feasibility of electrosynthesis of VO x by the cathodic electrogenerated base method is demonstrated and advantages of this technique are discussed. The electrogenerated base method results in the fabrication of VO x material, containing V 3+ , V 4+ and V 5+ species from VOSO 4 solutions. The deposition yield is studied in-situ at a constant voltage or constant current conditions using a quartz crystal microbalance. The method allows rigid control of the deposition yield. The results of X-ray photoelectron spectroscopy, thermogravimetic and differential thermal analyses allow the development of the new electrosynthesis mechanism. For the first time electric discharge machining (EDM) is used for the fabrication of patterned Ni current collectors for VO x supercapacitors. VO x material shows capacitive behavior in the positive potential range with a capacitance of 278.6 mF cm −2 . Asymmetric device containing VO x cathodes and γ-Fe 2 O 3 anodes shows a capacitance of 27.1 mF cm −2 in a voltage window of 1.5 V in Na 2 SO 4 electrolyte. The approach developed in this investigation opens an avenue for the fabrication of advanced patterned ceramic asymmetric supercapacitors with enlarged voltage windows.